Polynuclear Enantiopure SalenâMesoionic Carbene Hybrid

Article Cite This: Organometallics XXXX, XXX, XXX-XXX

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Polynuclear Enantiopure Salen−Mesoionic Carbene Hybrid Complexes Juliane Schmid, Wolfgang Frey, and René Peters* Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany S Supporting Information *

ABSTRACT: Salen ligands and mesoionic carbene (MIC) ligands constitute important ligand classes in homogeneous catalysis. In this article we describe the first integration of a salen moiety and MIC donors in the same catalyst entity. Homo- and heterometallic polynuclear metal complexes could be selectively prepared by first installing a metal center (Ni(II), Pd(II)) in the N2O2 salen sphere followed by metalation of the mesoionic carbenes (Ag(I), Pd(II)). The silver complexes could be used for transmetalations to form Au(III) complexes. Several complexes showed catalytic activity in the 1,4-addition of an oxindole to a nitroolefin.

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INTRODUCTION

Bi- and polyfunctional enantiopure metal complexes have been intensely studied as asymmetric catalysts, because the interplay of two or more catalyst functions (e.g., metal centers) can cause synergistic effects, which might be employed to tackle synthetically challenging stereoselective bond formations.1,2 Salen ligands are, in general, among the most useful chiral ligands in asymmetric metal catalysis, and bimetallic catalytic pathways have been suggested for various metal salen catalyzed reactions.3 A bimetallic cooperation can, for example, take place between two separate salen complexes,4 between two salen units linked by a tether5 (I in Figure 1), or using a single salen entity which can accommodate a second/third metal center in an additional coordination sphere (such as in II and III).6,7 Our group recently merged salens with N-heterocyclic carbene (NHC) moietiesanother very successful ligand motif in homogeneous catalysis8in a hybrid ligand system.9 Selective sequential metal coordination to the N2O2 salen sphere and the NHC sphere provided complexes such as IV for various metal/metal combinations. Further evolution of this catalyst design recently resulted in polyfunctional bisphenoxyimine complexes such as V, which enabled diastereodivergency in enantioselective 1,4-additions of oxindoles to nitroolefins.10 Mesoionic carbenes (MICs) are a special class of NHCs, for which no classical resonance structures can be drawn without a charge separation (zwitterions).11 MICs have been suggested to possess a larger carbanionic character than classical NHCs and hence to be stronger σ-donor ligands.11a Many MIC ligands have been prepared from 1,2,3-triazolium salts.11 The latter are often readily available by regioselective 1,3-dipolar cycloadditions of alkynes and organic azides,12 also known as a click reaction, followed by regioselective N-alkylation.13,14 © XXXX American Chemical Society

Figure 1. (top) Examples of bi-/polynuclear asymmetric salen catalysts (I−III). (bottom) Example for a binuclear salen/NHC hybrid system (IV) and a structurally related polyfunctional catalyst (V).

Received: September 27, 2017

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DOI: 10.1021/acs.organomet.7b00729 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics Due to their unique electronic properties MIC ligands have been intensely investigated in coordination chemistry15 and transition-metal catalysis, where they have demonstrated their potential, e.g., in various C−C bond forming reactions.16 Due to the attractive properties of both salen and MIC ligands, the goal of the presented study was to merge both of them in single molecular entities to generate bi-/polynuclear complexes of the general type presented in Figure 2, in which each metal center

Scheme 1. Synthesis of the Hybrid Ligands

Figure 2. General modular catalyst design of dinuclear salen/MIC complexes.

might possess distinct electronic features induced by the different local ligand spheres. Alternative hybrid ligands have already demonstrated unique features in coordination chemistry and catalysis.17 Herein, we report the syntheses of hybrid systems, in which M1 = Ni(II), Pd(II) is coordinated by the salen core and M2 = Ag(I), Au(III), Pd(II) by MIC donors. In addition, we present a preliminary study of the catalytic properties.

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RESULTS AND DISCUSSION Synthesis of the Hybrid Salen-MIC Ligands. To prepare the 1,2,3-triazolium units of the ligand precursors, Cu-catalyzed 1,3-dipolar azide/alkyne cycloadditions (CuAAC reactions)13 were performed in the key step. For this purpose the benzylic azide 4 was prepared from salicylic aldehyde 3 via nucleophilic displacement at the benzylic bromide moiety using NaN3 in DMSO (Scheme 1). The benzylic bromide itself was available in high yield in two steps from 4-tert-butylphenol (1) using literature procedures.18 The solid azide 4 was analytically pure after aqueous workup without the need for an additional purification step and was directly used in a CuAAC reaction, which was performed in analogy to a protocol by Rao et al.19 The 1,2,3-triazoles 5-Ph, 5-Pr, and 5-Mes were prepared in good to high yields as single regioisomers using phenylacetylene (E-1), 1-pentyne (E-2), and mesitylacetylene (E-3) as coupling partners, respectively. Preparation of 5-Mes required a prolonged reaction time (72 h) for full conversion, probably due to steric hindrance by the mesityl residue. The constitution with the expected 1,4-disubstitution pattern13,15a was confirmed by X-ray crystal structure analysis of 5-Mes (Figure 3).20 The subsequent N(3) alkylation required different protocols to form the different triazolium salts 6 in satisfactory yields. 6aPr was regioselectively formed in quantitative yield by treatment of 5-Pr with excess iodomethane in CH2Cl2 at room temperature. 2D-NMR spectra (COSY, HSQC, HMBC) confirmed the expected alkylation of N(3) (for details see the Supporting Information). The regioselective N(3) alkylation of 5-Pr and 5-Mes was also achieved in high yields with [Me3O]BF4 in CH2Cl2 at room temperature. In contrast, with 5-Mes MeI and (MeO)2SO2 reacted sluggishly and side products were formed,

Figure 3. Crystal structure of 5-Mes.

which could not be removed. For 6-Mes the constitution has been confirmed by 2D-NMR (Supporting Information). Unfortunately, 6-Ph was not obtained in pure form. Whereas with MeI no reactivity was observed in either CH2Cl2 or MeCN, (MeO)2SO2 furnished an impure product. With [Me3O]BF4 the reactivity was high (94% N-alkylation), but a 4/1 mixture of isomers was formed. The salicylic aldehyde derivatives 6a-Pr, 6b-Pr, and 6-Mes were then used for the condensation with (1R,2R)-(−)-(1,2)diaminocyclohexane9 to form the functionalized salen ligands 7a-Pr, 7b-Pr, and 7-Mes, respectively. Purification by washing with Et2O removed all nonionic components and provided pure material in high yields. Complexations by the N2O2 Salen Sphere. Nickel(II). The Ni(II) salen complexes 8a-Ni, 8b-Ni, and 9-Ni were obtained by addition of the corresponding salen ligands to NiCp2 in CH2Cl2 (Scheme 2). The use of 4 Å molecular sieves was necessary to avoid imine hydrolysis. After 15 h the redbrown complexes 8a-Ni, 8b-Ni, and 9-Ni were obtained in high yields which were found to be remarkably stable against air and water. Due to their diamagnetic behavior well-resolved 1H NMR spectra could be recorded and suggest a C2-symmetric structure with a square-planar Ni(II) center. B


Article

Organometallics Scheme 2. Synthesis of Ni(II) Salen Complexes

Scheme 4. Synthesis of Heterobinuclear Ni(II)/Ag(I) and Pd(II)/Ag(I) Complexes

Palladium(II). Pd(II) complexes 8a-Pd, 8b-Pd, and 9-Pd were accessible using Pd(OAc)2 as combined metal source/ base in analogy to our previous studies (Scheme 3).9a The Scheme 3. Synthesis of Pd(II) Salen Complexes

containers. In solution and on exposure to light a rapid decomposition to the ligands 7 under formation of Ag(0) was observed. According to (a) the 1H NMR spectra, which show partially very broad peaks for two signal sets, and (b) some unresolved signals in 13C NMR experiments especially for the triazolylidene carbon, the silver MIC complexes 10/11 are assumed to exist in equilibria between two species as depicted in Scheme 4. Equilibria of similar species have been observed and proposed before for a number of related Ag(I)-NHC complexes.22 Au(III) Complexes. Au(III) complexes 12 were formed over two steps starting from 11. In analogy to a transmetalation protocol by Albrecht,23 11 was first treated with 2.1 equiv of (Me2S)AuCl in CH2Cl2 at room temperature in the presence of 4 Å molecular sieves (Scheme 5).

expected C2-symmetric isomers are also likely in these cases, as judged from the 1H NMR spectra with a single set of signals. 8a-Pd, 8b-Pd, and 9-Pd seemed to be bench-stable in the solid state, as they showed no release of Pd(0) or decomposition for the duration of this project. The relatively high robustness of the Ni and Pd complexes then allowed for the study of their transformations into polynuclear hybrid complexes. Complexation Studies of the Triazolylidene Sphere. Ag(I) Complexes. In 2008 Albrecht et al. showed that Ag(I)MIC complexes are readily accessible and very useful precursors for the preparation of a large variety of other metal-MIC complexes by a transmetalation route.11a Since then this strategy has often been used successfully.21 For that reason we also intended to form the corresponding metal salen/AgMIC hybrid complexes. However, treatment of complexes 8 and 9 under standard conditions with Ag2O in dry CH2Cl2 at room temperature for 24 h under exclusion of light did not provide the targeted heteronuclear complexes. For the mesitylsubstituted triazolium salts 9 no conversion was found, whereas 8b-Ni and 8b-Pd resulted in undefined products, in which no Ag could be detected by mass spectrometry. Sarkar has recently reported the formation of Ag-MIC complexes by a combination of Ag2O and cesium carbonate to facilitate the deprotonation event at the carbene precursor.21a We thus applied those conditions to the monometallic triazolium tetrafluoroborate salts and thereby obtained the heteronuclear complexes 10 and 11 in good yields (Scheme 4). These transformations proceeded smoothly, and no side reactions or decomposition products have been observed. The products were analyzed by 1H NMR, 13C NMR, and ESI-MS. All Ag(I)-MIC complexes were stable in the solid state when they were stored under a nitrogen atmosphere in dark

Scheme 5. Synthesis of Heterotrinuclear Ni(II) and Pd(II)/ Au(III) Complexes

The 1H NMR spectra of the crude products of this initial transformation revealed the presence of several compounds. Conversion of these complex mixtures into single species could not be accomplished by heating, as 1H NMR experiments showed. Spectra remained unchanged until 60 °C, where first signs of decomposition occurred. We believe that equilibria similar to those suggested for the above silver complexes 10 and 11 might explain the presence of the several species.24 Since the different species could not be isolated as pure compounds with a defined structure, the crude product mixtures were used for further experiments. C


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Organometallics To obtain defined compounds, we then tried to oxidize the Au(I) into Au(III) centers. In contrast to Au(I) MIC complexes Au(III) MIC complexes have scarce precedent in the literature.25 By oxidation with PhICl2 the corresponding Au(III)-MIC complexes 12 could be obtained in satisfactory yields, providing satisfactory microanalyses.26 Decomposition of the salen core was not observed under oxidation conditions. The solid-state structure of 12-Ni could be determined by Xray analysis, confirming the assumed oxidation state and constitution of the trinuclear complex (Figure 4).27 The nearly

Scheme 6. Synthesis of Heterotrinuclear Ni(II)/Pd(II)2 and Homotrinuclear Pd(II)/Pd(II)2 Complexes

Therefore, structural parameters cannot be discussed. In any event the crystal structure showed one palladium center per MIC in a distorted-square-planar coordination geometry bridged by iodine (Figure 5), a binding motif that was previously observed and described by Albrecht for Pd complexation of triazolium systems.32 As the 1H NMR signals

Figure 4. Crystal structure of heterotrinuclear complex 12-Ni.

C2 symmetric compound thus contains one Au(III) center per MIC unit and each Au(III) adopts a nearly perfect square planar coordination sphere with Au−C bond lengths of 1.998(7) and 2.007(7) Å. The distance between both Au atoms is almost 10 Å. Interestingly, the gold centers are located directly above and in close proximity to the C(4)−C(5) bonds of the phenolate rings. The shortest Au···C distance was found to be 3.23 Å. On the basis of the van der Waals radii, the C···Au separations would be expected to be ≥3.36 Å, if there is no bonding character between these atoms.28 We thus suggest the possibility of a weak π interaction, which might contribute to stabilize the 1,2,3-triazolylidene Au(III) complexes or even facilitate their formation. Reinspection of the NMR spectra of the corresponding Au(I) intermediates revealed that they also already contained small amounts of the Au(III) complexes 12 (around 10 mol %). The partial oxidation might have been triggered by unreacted (Me2S)AuCl.29 Pd(II) Complexes. Pd(II) complexations by the MIC donors could be performed by direct metalations.11a,30 For this purpose the Ni(II) and Pd(II) salen complexes 8a-Ni and 8a-Pd were treated with Pd(OAc)2 and sodium iodide in CH2Cl2 overnight at 30 °C (Scheme 6). In both cases the products were formed in high yields. This was surprising, because in our previous investigations on related binuclear salen/bis-NHC complexes IV (Figure 1) Pd(II) could not be installed starting from the bisazolium precursors and a redox transmetalation had to be developed.9a,b A crystal of complex 14-Pd suitable for X-ray analysis could be obtained, showing the presence of two different rotamers.31 Unfortunately, though, the crystals were very fragile when they were taken out of solution and suffered from decomposition during measurement due to evaporation of 1,2-dichloroethane.

Figure 5. Two different rotamers in the crystal structure of 14-Pd. D


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Organometallics

were selectively prepared by consecutively installing a metal center (Ni(II), Pd(II)) in the N2O2 salen sphere and metalation of the mesoionic carbene units (Ag(I), Pd(II)). The best catalytic activity in the 1,4-addition of an oxindole to a nitroolefin was observed for a Pd(II)/Ag(I) hybrid complex. Polynuclear Au(III) MIC complexes were accessible by transmetalations from the Ag complexes and subsequent oxidation of the Au(I) intermediates.

of 13-Ni and 14-Pd are quite broad, we suggest a dynamic equilibrium between both rotamers (and maybe even further species) in solution. Additionally, a complex fragment of 14-Pd missing an iodide [C42H58N8O2I3Pd3+] was detected via ESI-MS with the correct exact mass and isotopic pattern. In our previous studies with hybrid salen/bis-NHC ligands, metal/metal combinations of Ni(II)/Pd(II) and Pd(II)/Pd(II) coordinated by the N2O2 sphere and bis-NHC donors, respectively, were also investigated.9a,b,32 In that case the structure determined by X-ray crystal structure analyses was different from that of the trinuclear complex 14-Pd. For anions with poor Lewis basicity (such as triflate and tetrafluoroborate) compartmental binuclear complexes IV were formed (as depicted in Figure 1), in which the phenolate O atoms serve as bridging ligands. In contrast, in the presence of Lewis basic anions such as halides, tosylate, and carboxylates the anions were found to coordinate to M2 in binuclear complexes, thus cleaving the O bridges. Complexation of two Pd(II) centers by the two NHCs as observed with the two MICs was not found in any case there. Preliminary Studies of Applications in Catalysis. The prepared complexes were studied in the 1,4-addition of oxindole E-5 to nitroolefin E-4 under the conditions shown in Table 1.33 In general, the product was formed in higher

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General Considerations. All reactions with substances that are sensitive toward air or moisture were carried out in dried glassware (24 h at 150 °C in an oven or 5 min at 650 °C in vacuo) under a positive pressure of nitrogen (ca. 1.2 bar). Liquids were added via syringe. Solvents were evaporated at 40 °C and 600−10 mbar or at ambient temperature with constant nitrogen flow. Reactions were monitored via 1H NMR or TLC performed on silica gel plates (silica 60, 0.2 mm). Visualization occurred by fluorescence quenching under UV light (λ 254 nm) and/or by staining with KMnO4/NaOH. Yields are given, if not indicated otherwise, with regard to the isolated, analytically pure product. Methylene chloride, diethyl ether, acetonitrile, and n-pentane were dried by a solvent purification system. DMSO and DMF were purchased in crown-capped bottles and used without further purification. Methanol, ethanol, n-hexane, and isopropyl alcohol (HPLC grade) were used without further purification, whereas technical grade solvents used for workup and purification of substances stable toward air and moisture such as DCM, ethyl acetate, petroleum ether, and acetone were distilled prior to use. Additional chemicals were purchased and, unless indicated otherwise, used without further purification. Deuterated solvents for NMR experiments were stored at 4 °C over molecular sieves and, if necessary, stirred over calcium chloride, filtered through a pad of activated aluminum oxide, and distilled under an inert gas atmosphere. NMR spectra were measured with 300/400/500/700 MHz spectrometers at 21 °C. Chemical shifts δ are given in ppm relative to the residual solvent peak of the used deuterated solvent. Coupling constants J are given in Hz with regard to multiplicity (s (singlet), d (doublet), t (triplet), q (quartet), quint (quintet), sext (sextet), m (multiplet), b (broad signal)). IR spectra and elemental analyses were measured by the analytical service of Universität Stuttgart. Samples were either measured in the solid state or, if liquid, as a solution in DCM or chloroform. IR bands are given in units of wavenumbers (cm−1). Optical rotation was measured on a polarimeter operating at the sodium D line (λ 589 nm) and quicksilver lines (λ1 578 nm and λ2 546 nm) with a 100 mm path cell length. Melting points were measured in open glass capillaries and are uncorrected. Mass spectra (CI, EI, or ESI) were obtained from the MS service of the Universität Stuttgart. Single-crystal X-ray analysis was performed by Dr. Wolfgang Frey (Universität Stuttgart) (Cu Kα 1.54178 Å and Mo Kα 0.71073 Å)). UV−vis spectra were recorded using a UV−vis spectrometer with deuterium and tungsten lamps operating between 190 and 1100 nm. Synthesis and Characterization of the MIC Complexes. Metal complexation into the salen sphere9a and MIC sphere21a of the ligands was achieved following literature procedures optimized for the described systems. Formation and purity of the ligands and complexes were determined by mass spectrometry as well as 1H and 13C NMR spectroscopy and 2D-NMR experiments. MIC complexation by Ag(I) was established by ESI-MS spectra with fitting of the isotopic pattern of distinct m/z peaks for the described silver-MIC complexes and 1 H/13C NMR spectroscopy. Thereby formation of the MIC complexes was confirmed by the absence of the characteristic triazolium proton in 1 H NMR spectroscopic data in comparison to the monometallic complexes as well as by appearance of the characteristic signal for the carbene carbon in 13C measurements in the region of 160−169 ppm, which has been reported as an infallible indication for the existence of carbene complexes in solution.21a Transmetalation to form the corresponding Au-MIC complexes was accompanied by precipitation of silver salts from the reaction mixture. In contrast to the silver

Table 1. Catalytic 1,4-Addition of Oxindoles to Nitroolefins

a

catalyst

conversion (%)a

yield (%)a

dr (D1/D2)a

8a-Ni 8a-Pd 9-Ni 9-Pd 10-Ni 10-Pd 11-Ni 11-Pd 13-Nib 14-Pdb

73 95 70 72 71 78 76 >99 25 50

69 94 55 72 57 72 75 >99 24 48

76/24 74/26 68/32 75/25 61/39 62/38 61/39 56/44 72/25 71/29

Determined by 1H NMR with an internal standard. decomposition was observed during catalytic reaction.

b

EXPERIMENTAL SECTION

Catalyst

yields with the mononuclear Pd(II) and polynuclear Pd(II)/ Ag(I) complexes (up to >99% with the polynuclear Pd(II)/ Ag(I) complex 11-Pd) with fewer side reactions in comparison to the use of the corresponding Ni(II) complexes, while the diastereomeric ratios were always quite similar. The trinuclear complexes 13-Ni and 14-Pd showed decomposition, which was observable by formation of a metal mirror during the catalytic reaction. This resulted in low product yields. In all cases both diastereomers were racemic.

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CONCLUSION In conclusion, we have reported the first polynuclear enantiopure salen/mesoionic carbene hybrid complexes. They E


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Organometallics carbene complexes, the obtained Au-MIC complexes were no longer sensitive toward light. Gold carbene fragments were detected via ESIMS, and the expected signal for the carbene carbon was assigned for the desired complexes in 13C NMR spectra. The crude Au(I)-MIC complexes obtained after transmetalation were subjected to oxidation with a hypervalent iodine compound following modified literature conditions26 to yield the Au(III)-MIC complexes as defined species. Proof of identity of the Au(III)-MICs was given by single-crystal X-ray diffraction analysis and mass spectrometry. Purity of the complexes was established by NMR spectroscopy as well as combustion analysis. The trinuclear iodine-bridged Pd(II)-MICs were obtained via metalation of the triazolium compounds; they were characterized by NMR spectroscopy, and their structure was identified via X-ray analysis as well as ESI-MS spectrometry. General Procedures. General Procedure for the Synthesis of 1,2,3-Triazoles 5 (GP1).19 To synthesize the triazoles 5, a coppercatalyzed cycloaddition (CuAAC) was performed following a modified pathway by Pathak et al.19 Copper(II) acetate hydrate (0.10 equiv) was suspended with 2-aminophenol (0.05 equiv) in water (2 mL mmol−1 with regard to the azide) and 3-(azidomethyl)-5-(tert-butyl)2-hydroxybenzaldehyde (4; 1.0 equiv) was added as a solution in DCM (2 mL mmol−1). The reaction mixture was stirred under reduction of pressure for 12−72 h at ambient temperature with a magnetic stirring bar. After completion of the reaction, which was monitored by TLC, the mixture was extracted with DCM and the organic phases were washed with water and brine and dried over sodium sulfate. After rotary evaporation of the solvent the crude product was purified via column chromatography on silica gel (silica 60, 0.04−0.07 mm). General Procedure for the Synthesis of Salens 7 (GP2).9d salen ligands 7 were synthesized from triazolium salts 6 and enantiomerically pure diamines. The triazolium salt (2.0 equiv) was diluted with degassed ethanol (20 mL mmol−1). Molecular sieves (4 Å) were added, and a solution of the corresponding diamine (1.0 equiv) in degassed ethanol was added via syringe. The reaction mixture was stirred under an inert gas atmosphere overnight until complete conversion. Then the mixture was filtrated over Celite and the solvent was evaporated. The crude product could be purified by precipitation from DCM/diethyl ether, and the pure ligands 7 were obtained as yellow solids. General Procedure for the Complexation of Metal Cations into the Salen Sphere of the Ligands (GP3).9a To synthesize the salen metal complexes 8 and 9, the metal source (1.0 equiv) and molecular sieves (4 Å) were suspended in dry DCM (10 mL mmol−1) and the ligand 7 (1.0 equiv) was added as a solution in DCM. The reaction mixture was stirred under an inert gas atmosphere for 20 h and then filtered over a short pad of Celite. After evaporation of the solvent and washing of the crude product with diethyl ether or n-pentane, the corresponding complex was obtained as an analytically pure product. General Procedure for the Complexation of Silver Cations into the MIC Sphere of the Ligands (GP4).21a To synthesize the silver carbene complexes 10 and 11, a mixture of silver oxide (5.0 equiv), predried potassium chloride (4.0 equiv), cesium carbonate (6.0 equiv), and the corresponding monometallic salen complex 8 or 9 (1.0 equiv) was suspended in a flask equipped with molecular sieves 4 Å and covered in aluminum foil in dry, degassed acetonitrile (10 mL mmol−1) at ambient temperature. The reaction mixture was stirred under an inert gas atmosphere and with exclusion of light for 48 h. After filtration of the mixture through a short pad of Celite, evaporation of the solvent, and, if necessary, washing with n-pentane, the carbene complexes were isolated as pure compound mixtures of two isomers. General Procedure for the Transmetalation of Silver Carbene Complexes to the Corresponding Au(I)-MICs and Subsequent Oxidation to Au(III) (GP5). Transmetalation to gold23 was carried out by addition of AuCl(SMe2) (2.1 equiv) to a solution of the corresponding silver carbene in dry DCM at room temperature in a flask equipped with MS 4 Å and covered in aluminum foil. The reaction mixture was stirred for 24 h and then filtered through a short pad of Celite to remove silver salts and molecular sieves. After

evaporation of the solvent and precipitation from DCM/n-pentane the gold complexes 12 were isolated as a mixture of different gold-MIC species. The crude product was then mixed with freshly prepared34 PhICl2 (2.1 equiv) diluted with dry DCM (0.1 mL μmol−1) and stirred at ambient temperature until completion of the oxidation (up to 15 h). After filtration over Celite and precipitation from DCM/n-pentane, the Au(III)-MIC complexes were isolated as pure compounds. General Procedure for the Preparation of Palladium-Salen/ Palladium-MIC Complexes (GP6). Direct palladium carbene formation of the mononuclear salen complexes was accomplished by addition of palladium acetate (2.2 equiv) and sodium iodide (2.2 equiv) to the corresponding nickel or palladium salen. The mixture was stirred with molecular sieves 4 Å in dry DCM (1 mL μmol−1) for 24 h at 30 °C under a nitrogen atmosphere. At complete complexation the mixture was filtered over Celite, the solvent was reduced to a volume of approximately 1 mL, and the complex was precipitated from n-pentane. Synthesis of the Salen Ligands. 5-(tert-Butyl)-2-hydroxy-3-[(4phenyl-1H-1,2,3-triazol-1-yl)methyl]benzaldehyde (5-Ph). Triazole 5-Ph was synthesized according to GP1 using 4 (466.5 mg, 2.0 mmol, 1.0 equiv) and phenylacetylene (E-1; 204.3 mg, 190.0 μL, 2.0 mmol, 1.0 equiv). After purification via column chromatography (petroleum ether/ethyl acetate 4/1, Rf = 0.49) 5-Ph was obtained as a colorless to pale yellow solid (500.1 mg, 1.5 mmol, 75%). C20H21N3O2: mol wt 335.40 g mol−1. 1H NMR (CDCl3, 300 MHz, 21 °C): δ 11.39 (s, 1H, OH), 9.92 (s, 1H, CHO), 7.94 (s, 1H, H−trz), 7.81 (d, J = 7.7, 2H, oH-Ph), 7.67 (d, J = 2.4, 1H, H−Ar), 7.57 (d, J = 2.4, 1H, H-Ar), 7.40 (t, J = 7.7, 2H, m-H-Ph), 7.32 (m, J = 7.7, 1H, p-H-Ph), 5.63 (s, 2H, Ar−CH2−Ntrz), 1.31 (s, 9H, (CH3)3). 13C NMR (CDCl3, 125 MHz, 21 °C): δ 197.0 (1C, CHO), 157.3 (1C, CAr−OH), 148.1 (1C, CAr-tBu), 143.5 (1C, CAr), 135.6 (1C, CAr), 131.0 (1C, CAr), 130.7 (1C, CPh), 128.9 (2C, CPh), 128.1 (1C, CPh), 125.9 (1C, CPh), 123.0 (1C, CPh), 120.4 (1C, CTrz−H), 48.2 (1C, CH2−Trz), 34.3 (1C, CtBu), 31.3 (3C, (CH3)3). IR (solid): ν̃ 3133, 2966, 2867, 1654, 1462, 1364, 1264, 1221, 1076, 1047, 987, 889, 768, 698, 532. HRMS (ESI): m/z calcd for [C20H21N3O2]Na+, 358.1526; found, 358.1514. Mp: 119− 121 °C. 5-(tert-Butyl)-2-hydroxy-3-[(4-propyl-1H-1,2,3-triazol-1-yl)methyl]benzaldehyde (5-Pr). Triazole 5-Pr was synthesized according to GP1 using 4 (1.10 g, 4.7 mmol, 1.0 equiv) and 1-pentyne (E-2; 321.2 mg, 464.9 μL, 4.7 mmol, 1.0 equiv). After purification via column chromatography (petroleum ether/ethyl acetate 4/1, Rf = 0.24) 5-Pr was obtained as a colorless to pale yellow solid (1.00 g, 3.3 mmol, 71%). C17H23N3O2: mol wt 301.38 g mol−1. 1H NMR (CDCl3, 300 MHz, 21 °C): δ 11.31 (s, 1H, OH), 9.90 (s, 1H, CHO), 7.53 (s, 2H, H−Ar), 7.43 (s, 1H, H−trz), 5.54 (s, 2H, Ar−CH2−Ntrz), 2.66 (t, J = 7.5, 2H, CH3−CH2−CH2C), 1.72−1.60 (sext, J = 7.5, 2H, CH3− CH2−CH2C), 1.28 (s, 9H, (CH3)3), 0.94 (t, J = 7.5, 3H, CH3-CH2− CH2C). 13C NMR (CDCl3, 75 MHz, 21 °C): δ 196.9 (1C, CHO), 157.2 (1C, CAr−OH), 148.6 (1C, CAr), 143.4 (1C, CAr), 135.3 (1C, CAr), 130.8 (1C, CAr), 123.4 (1C, CAr), 121.4 (1C, CAr), 120.3 (1C, CTrz−H), 47.9 (1C, CH2−Trz), 34.3 (1C, CtBu), 31.3 (3C, (CH3)3), 27.8 (2C, CH2−CH2−CH3), 22.8 (2C, CH2−CH2−CH3), 13.9 (2C, CH2−CH2−CH3). IR (solid): ν̃ 3133, 2966, 2867, 1654, 1462, 1364, 1264, 1221, 1076, 1047, 987, 889, 768, 698, 532. HRMS (ESI): m/z calcd for [C17H23N3O2]Na+, 324.1682; found, 324.1667. Mp: 53−55 °C. 5-(tert-Butyl)-2-hydroxy-3-[(4-mesityl-1H-1,2,3-triazol-1-yl)methyl]benzaldehyde (5-Mes). Triazole 5-Mes was synthesized according to GP1 using 4 (1.17 g, 5.0 mmol, 1.0 equiv) and mesitylacetylene (E-3; 721.1 mg, 782.9 μL, 5.0 mmol, 1.0 equiv). After purification via column chromatography (petroleum ether/ethyl acetate 4/1, Rf = 0.47) 5-Mes was obtained as a colorless crystalline solid (1.27 g, 3.4 mmol, 67%). C23H27N3O2: mol wt 377.48 g mol−1. 1 H NMR (CDCl3, 300 MHz, 21 °C): δ 11.32 (s, 1 H, OH), 9.92 (s, 1H, CHO), 7.57 (s, 1H, H−trz), 7.55 (d, J = 2.5, 1H, H−Ar), 7.47 (d, J = 2.4, 1H, H−Ar), 6.92 (s, 2H, H−Mes), 5.68 (s, 2H, Ar−CH2−Ntrz), 2.30 (s, 3H, p-Mes−CH3), 2.09 (s, 6H, o−Mes(CH3)2), 1.29 (s, 9H, (CH3)3). 13C NMR (CDCl3, 125 MHz, 21 °C): δ 197.0 (1C, CHO), 143.4 (1C, CAr−OH), 138.2 (1C, CAr-tBu), 137.8 (1C, CMes-Trz), F


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Organometallics 134.6 (1C, CMes), 130.6 (2C, CMes), 128.4 (2C, CMes), 127.3 (2C, CAr), 123.5 (2C, CAr), 120.3 (1C, CTrz−H), 48.3 (1C, CH2−Trz), 34.3 (1C, CtBu), 31.3 (3C, (CH3)3), 21.2 (1C, (CH3)Mes), 20.8 (2C, (CH3)Mes). IR (solid): ν̃ 3079, 2958, 1648, 1450, 1266, 1140, 938, 829, 746, 476. HRMS (ESI): m/z calcd for [C23H27N3O2]Na+, 400.1995; found, 400.2001. Mp: 130−132 °C. 1-[5-(tert-Butyl)-3-formyl-2-hydroxybenzyl]-3-methyl-4-propyl1H-1,2,3-triazol-1-yl-3-ium Iodide (6a-Pr). To synthesize 1-[5-(tertbutyl)-3-formyl-2-hydroxybenzyl]-3-methyl-4-propyl-1H-1,2,3-triazol3-ium iodide 6a-Pr, 5-Pr (450.0 mg, 1.5 mmol, 1.0 equiv) was dissolved in dry DCM (5 mL mmol−1) and iodomethane (165.6 mg, 511.2 μL, 8.2 mmol, 5.5 equiv) was added under nitrogen. The reaction mixture was stirred for 120 h, whereas every 24 h an additional 5.5 equiv of iodomethane was added via syringe. After complete methylation as monitored by TLC, all volatiles were removed under reduced pressure and the residue was washed with diethyl ether several times. The crude product was then dissolved in DCM, and after evaporation of the solvent 6a-Pr was obtained as a yellow solid (633.4 mg, 1.4 mmol, 96%). C18H26IN3O2: mol wt 443.33 g mol−1. 1H NMR (CDCl3, 300 MHz, 21 °C): δ 11.27 (s, 1H, OH), 9.91 (s, 1H, CHO), 8.81 (s, 1H, H−trz), 8.08 (d, J = 2.5, 1H, H−Ar), 7.65 (d, J = 2.4, 1H, H−Ar), 5.93 (s, 2H, Ar−CH2−Ntrz), 4.23 (s, 3H, Ntrz−CH3), 2.90 (t, J = 7.5, 2H, CH3−CH2−CH2C), 1.80 (sext, J = 7.5, 2H, CH3−CH2−CH2C), 1.34 (s, 9H, (CH3)3), 1.04 (t, J = 7.5, 3H, CH3-CH2−CH2C). 13C NMR (CDCl3, 125 MHz, 21 °C): δ 196.9 (1C, CHO), 157.9 (1C, CAr−OH), 144.4 (1C, CAr), 144.1 (1C, CAr), 137.2 (1C, CAr), 132.3 (1C, CAr), 129.4 (1C, CAr), 120.4 (1C, CTrz− H), 119.3 (1C, CAr), 52.7 (1C, CH2−Trz), 38.7 (1C, Ntrz−CH3), 34.7 (1C, CtBu), 31.4 (3C, (CH3)3), 26.0 (2C, CH2−CH2−CH3), 20.8 (2C, CH2−CH2−CH3), 13.7 (2C, CH2−CH2−CH3). IR (solid): ν̃ 3151, 2983, 2868, 1658, 1616, 1473, 1382, 1271, 1215, 1013, 611, 503. HRMS (ESI): m/z calcd for [C18H26N3O2+], 316.2020; found, 316.2016. Mp: 168−171 °C. 1-[5-(tert-Butyl)-3-formyl-2-hydroxybenzyl]-3-methyl-4-propyl1H-1,2,3-triazol-1-yl-3-ium Tetrafluoroborate (6b-Pr). To synthesize 1-[5-(tert-butyl)-3-formyl-2-hydroxybenzyl]-3-methyl-4-propyl-1H1,2,3-triazol-3-ium tetrafluoroborate (6b-Pr), trimethyloxonium tetrafluoroborate (147.9 mg, 0.7 mmol, 1.0 equiv) was suspended in dry DCM (0.5 mL mmol−1) and 5b-Pr (200.0 mg, 0.7 mmol, 1.0 equiv) was added as a solution in DCM quickly via syringe. The reaction mixture was stirred at ambient temperature for 24 h. The solvents were removed by rotary evaporation, and the residue was precipitated from DCM/diethyl ether. After drying in vacuo 6b-Pr was obtained as a pale red oil (224.0 mg, 0.6 mmol, 84%). C18H26BF4N3O2: mol wt 403.23 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 11.27 (s, 1H, OH), 9.91 (s, 1H, CHO), 8.81 (s, 1H, H−trz), 8.08 (d, J = 2.5, 1H, H−Ar), 7.65 (d, J = 2.4, 1H, H−Ar), 5.93 (s, 2H, Ar−CH2−Ntrz), 4.23 (s, 3H, Ntrz−CH3), 2.90 (t, J = 7.5, 2H, CH3−CH2−CH2C), 1.80 (sext, J = 7.5, 2H, CH3−CH2−CH2C), 1.34 (s, 9H, (CH3)3), 1.04 (t, J = 7.5, 3H, CH3−CH2−CH2C). 13C NMR (CD2Cl2, 100 MHz, 21 °C): δ 197.4 (1C, CHO), 158.0 (1C, CAr−OH), 145.0 (1C, CAr), 144.4 (1C, CAr), 137.0 (1C, CAr), 132.8 (1C, CAr), 128.6 (1C, CAr), 120.7 (1C, CTrz−H), 119.5 (1C, CAr), 52.7 (1C, CH2−Trz), 38.0 (1C, Ntrz− CH3), 34.8 (1C, CtBu), 31.3 (3C, (CH3)3), 25.4 (2C, CH2−CH2− CH3), 20.8 (2C, CH2−CH2−CH3), 13.6 (2C, CH2−CH2−CH3). 19F NMR (CD2Cl2, 376 MHz, 21 °C): δ −152.5. IR (in CD2Cl2): ν̃ 3131, 2965, 2875, 1654, 1621, 1582, 1468, 1387, 1278, 1223, 1056, 1010, 829, 721, 520. HRMS (ESI): m/z calcd for [C18H26N3O2+], 316.2020; found, 316.1999. 1-[5-(tert-Butyl)-3-formyl-2-hydroxybenzyl]-3-methyl-4-mesityl1H-1,2,3-triazol-1-yl-3-ium Tetrafluoroborate (6-Mes). To prepare 1-[5-(tert-butyl)-3-formyl-2-hydroxybenzyl]-3-methyl-4-mesityl-1H1,2,3-triazol-3-ium tetrafluoroborate (6-Mes), trimethyloxonium tetrafluoroborate (293.9 mg, 2.0 mmol, 1.5 equiv) was suspended in dry DCM (0.5 mL mmol−1) and 5-Mes (500.0 mg, 1.3 mmol, 1.0 equiv) was added as a solution in DCM quickly via syringe. The reaction mixture was stirred at ambient temperature for 24 h before the excess Meerwein’s salt was removed by hydrolysis with wet methanol (stirring of the reaction mixture with 2 mL of methanol for 30 min). The solvents were removed by rotary evaporation, and the residue was

precipitated from DCM/diethyl ether. After drying in vacuo 6-Mes was obtained as a pale red solid (617.5 mg, 1.3 mmol, 97%). C24H30BF4N3O2: mol wt 479.33 g mol−1. 1H NMR (CD2Cl2, 300 MHz, 21 °C): δ 11.36 (s, 1H, OH), 9.93 (s, 1H, CHO), 8.39 (s, 1H, H−trz), 7.97 (d, J = 2.5, 1H, H−Ar), 7.72 (d, J = 2.4, 1H, H−Ar), 7.06 (s, 2H, H−Ar), 5.93 (s, 2H, Ar−CH2−Ntrz), 3.94 (s, 3H, Ntrz−CH3), 2.35 (s, 3H, (CH3)Mes), 2.02 (s, 6H, (CH3)2, Mes), 1.37 (s, 9H, (CH3)3). 13 C NMR (CD2Cl2, 125 MHz, 21 °C): δ 197.6 (1C, CHO), 158.1 (1C, CAr−OH), 144.5 (1C, CAr−tBu), 143.1 (1C, CMes-Trz), 142.3 (1C, CMes), 138.8 (1C, CMes), 137.2 (1C, CMes), 132.7 (1C, CAr), 130.5 (1C, CAr), 129.7 (1C, CAr), 120.9 (1C, CTrz−H), 119.7 (1C, CAr), 117.9 (1C, CAr), 53.7 (1C, CH2−Trz), 37.9 (1C, Ntrz−CH3), 34.6 (1C, CtBu), 31.4 (3C, (CH3)3), 21.6 (1C, (CH3)Mes), 20.1 (2C, (CH3)Mes). 19F NMR (CDCl3, 235 MHz, 21 °C): δ −152.3. IR (solid): ν̃ 2957, 1650, 1465, 1049, 717, 519. HRMS (ESI): m/z calcd for [C24H30N3O2+], 392.2333; found, 392.2344. Mp: 70−74 °C. {[1,1′[(1R,2R)-1,2-Cyclohexanediylbis(azanylylidene)bis(methanylylidene)bis[5-(tert-butyl)-2-hydroxy-3,1-phenylene]bis(methylene)bis(4-propyl-3-methyl-1H-1,2,3-triazol-1-yl-3-ium)]} Iodide (7a-Pr). 7a-Pr was synthesized following GP2. 6a-Pr (500.0 mg, 1.1 mmol, 2.0 equiv) and molecular sieves were diluted with degassed ethanol, and (1R,2R)-(−)-1,2-diaminocyclohexane (64.4 mg, 0.6 mmol, 1.0 equiv) was added as a solution in ethanol via syringe. After precipitation from diethyl ether 7a-Pr was isolated as a yellow solid (503.9 mg, 0.5 mmol, 94%). C42H52I2N8O2: mol wt 964.82 g mol−1. 1H NMR (CDCl3, 300 MHz, 21 °C): δ 14.01 (s, 2H, OH), 8.68 (s, 2H, CHN), 8.44 (s, 2H, H−trz), 7.60 (d, J = 2.6, 2H, H−Ar), 7.34 (d, J = 2.6, 2H, H−Ar), 5.79 (d, 2H, Ar−CH2−Ntrz), 5.69 (d, 2H, Ar− CH2−Ntrz), 4.27 (s, 6H, Ntrz−CH3), 3.50 (m, 2H, CHCyhex), 2.93 (b, 4H, CH2−CH2−CH3), 1.93−1.36 (m, 4H, CH2−CH2−CH3 and 8H, (CH2)Cyhex), 1.26 (s, 18H, (CH3)3), 1.03 (t, J = 7.2, 3H, CH2−CH2− CH3). 13C NMR (CDCl3, 75 MHz, 21 °C): δ 164.9 (2C, CAr−OH), 159.2 (2C, Ctrz−nPr), 144.3 (2C, CAr−tBu), 141.6 (2C, CAr), 132.2 (2C, Ctrz−H), 130.8 (2C, CHN), 129.2 (2C, CAr), 118.7 (2C, CAr), 118.3 (2C, CAr), 71.4 (2C, CHCyhex), 53.4 (2C, Ar−CH2−Ntrz), 38.8 (2C, Ntrz−CH3), 34.2 (2C, CtBu), 33.1 (6C, CtBu), 31.6 (2C, (CH2)Cyhex), 25.9 (2C, CH2−CH2−CH3), 24.2 (2C, (CH2)Cyhex), 20.7 (2C, CH2−CH2−CH3), 13.7 (2C, CH2−CH2−CH3). IR (solid): ν̃ 3431, 2933, 2861, 1627, 1478, 1280, 1225, 1017, 826, 605. HRMS (ESI): m/z calcd for [C36H51N5O22+], 292.7016; found, 292.7005. Mp: −1 99−102 °C dec. [α]20 D (c = 1.05 mg mL , DCM): − 247.7. Cyclohexanediylbis(azanylylidene)bis(methanylylidene)bis[5(tert-butyl)-2-hydroxy-3,1-phenylene]bis(methylene)bis(4-propyl-3methyl-1H-1,2,3-triazol-1-yl-3-ium)]} Tetrafluoroborate (7b-Pr). 7bPr was synthesized following GP2. 6b-Pr (190.5 mg, 4.7 mmol, 1.0 equiv) and molecular sieves were diluted with degassed ethanol, and (1R,2R)-(−)-1,2-diaminocyclohexane (27.0 mg, 2.4 mmol, 2.0 equiv) was added as a solution in ethanol via syringe. After precipitation from diethyl ether 7b-Pr was isolated as a yellow solid (175.8 mg, 2.0 mmol, 84%). C42H52B2F8N8O2: mol wt 884.62 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 14.01 (s, 2H, OH), 8.68 (s, 2H, CHN), 8.44 (s, 2H, H−trz), 7.60 (d, J = 2.6, 2H, H−Ar), 7.34 (d, J = 2.6, 2H, H−Ar), 5.79 (d, 2H, Ar−CH2−Ntrz), 5.69 (d, 2H, Ar−CH2−Ntrz), 4.27 (s, 6H, Ntrz−CH3), 3.50 (m, 2H, CHCyhex), 2.93 (b, 4H, CH2−CH2−CH3), 1.93−1.36 (m, 4H, CH2−CH2−CH3 and 8H, (CH2)Cyhex), 1.26 (s, 18H, (CH3)3), 1.03 (t, J = 7.2, 3H, CH2−CH2−CH3). 13C NMR (CD2Cl2, 100 MHz, 21 °C): δ 165.3 (2C, CAr−OH), 159.2 (2C, Ctrz− nPr), 144.9 (2C, CAr−tBu), 141.9 (2C, CAr), 132.1 (2C, Ctrz−H), 130.9 (2C, CHN), 128.7 (2C, CAr), 118.9 (2C, CAr), 118.7 (2C, CAr), 72.0 (2C, CHCyhex), 53.4 (2C, Ar−CH2−Ntrz), 37.8 (2C, Ntrz− CH3), 34.4 (2C, CtBu), 33.4 (6C, CtBu), 31.3 (2C, (CH2)Cyhex), 25.4 (2C, CH2−CH2−CH3), 24.5 (2C, (CH2)Cyhex), 21.0 (2C, CH2−CH2− CH3), 13.6 (2C, CH2−CH2−CH3). 19F NMR (CD2Cl2, 376 MHz, 21 °C): δ −152.4. IR (solid): ν̃ 3136, 2958, 2872, 1630, 1603, 1583, 1481, 1394, 1365, 1283, 1227, 1029, 826, 749, 706, 633, 520. HRMS (ESI): m/z calcd for [C42H62N8O22+]: 355.2492, found, 355.2498. Mp: 119− −1 121 °C dec. [α]20 D (c = 1.00 mg mL , DCM): −562.7. {[1,1′[(1R,2R)-1,2-Cyclohexanediylbis(azanylylidene)bis(methanylylidene)bis[5-(tert-butyl)-2-hydroxy-3,1-phenylene]bis(methylene)bis(4-mesityl-3-methyl-1H-1,2,3-triazol-1-yl-3-ium)]} Tetrafluoroborate (7-Mes). 7-Mes was synthesized following GP2. 6G


Article

Organometallics

CH2−CH2−CH3), 24.6 (2C, (CH2)Cyhex), 20.5 (2C, CH2−CH2− CH3), 13.6 (2C, CH2−CH2−CH3). 19F NMR (CD2Cl2, 376 MHz, 21 °C): δ −152.5. IR (solid): ν̃ 2954, 2867, 2049, 1620, 1552, 1456, 1364, 1312, 1224, 1031, 868, 834, 796, 737, 557, 520. HRMS (ESI): m/z calcd for [C36H46N5O2Ni+], 626.2999; found, 626.2993. Mp: 178−181 −1 °C dec. [α]20 D (c = 1.05 mg mL , DCM): −619.2. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[4-mesityl-3methyl-1H-1,2,3-triazol-1-yl-3-ium]](2−)]nickel(II)} Tetrafluoroborate (9-Ni). The nickel(II) complex 9-Ni was synthesized according to GP3 using Ni(Cp)2 (17.4 mg, 92 μmol, 1.0 equiv) and a solution of ligand 7-Mes (95.3 mg, 92 μmol, 1.0 equiv) in dry DCM. The nickel salen complex 9-Ni was isolated as a red-brown solid (89.4 mg, 82 μmol, 89%). C54H68B2F4N8O2Ni: mol wt 1093.49 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 8.80 (s, 2H, CHN), 7.54 (s, 2H, H− trz), 7.39 (d, J = 2.2, 2H, H−Ar), 7.32 (d, J = 2.2, 2H, H−Ar), 7.00 (d, J = 9.9, 4H, H−Mes), 5.69 (d, J = 14.3, 2H, Ar−CH2−Ntrz), 5.43 (d, J = 14.3, 2H, Ar−CH2−Ntrz), 3.91 (s, 6H, Ntrz−CH3), 3.05 (m, 2H, (CH2)Cyhex), 3.50 (m, 2H, CHCyhex), 2.31 (s, 6H,(p−CH3)Mes), 2.17 (s, 6H, (o-CH3)Mes), 2.12 (s, 6H, (o-CH3)Mes), 1.96 (m, 6H, (CH2)Cyhex, 1.27 (s, 18H, (CH3)3). 13C NMR (CD2Cl2, 125 MHz, 21 °C): δ 160.2 (2C, CAr−ONi), 159.1 (2C, Ctrz−Mes), 142.7 (2C, CAr−tBu), 141.6 (2C, CAr), 139.1 (2C, CAr), 138.8 (2C, CMes), 138.6 (2C, CMes), 134.1 (2C, CAr), 132.1 (2C, Ctrz−H) 131.0 (2C, CHN), 129.6 (2C, CHMes), 129.4 (2C, CHMes), 122.1 (2C, CMes), 120.9 (2C, CAr), 118.4 (2C, CMes), 70.8 (2C, CHCyhex), 55.5 (2C, Ar−CH2−Ntrz), 37.5 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.4 (6C, CtBu), 29.3 (2C, (CH2)Cyhex), 24.6 (2C, (CH2)Cyhex), 21.4 (2C, (CH3)Mes), 20.3 (2C, (CH3)Mes), 20.0 (2C, (CH3)Mes). 19F NMR (CD2Cl2, 376 MHz, 21 °C): δ −152.8. IR (in CD2Cl2): ν̃ 2953, 2865, 1621, 1553, 1455, 1224, 1033, 954, 708, 576. HRMS (ESI): calcd for [C54H68N8O2Ni2+], 459.2404; −1 found, 459.2402. Mp: 163−166 °C dec. [α]20 D (c = 1.05 mg mL , DCM): −431.2. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[3-methyl-4propyl-1H-1,2,3-triazol-1-yl-3-ium]](2−)]palladium(II)} Iodide (8aPd). The palladium(II) complex 8a-Pd was synthesized according to GP3 using Pd(OAc)2 (17.5 mg, 78 μmol, 1.0 equiv) and sodium acetate (12.8 mg, 155 μmol, 2.0 equiv) as base. To this suspension was added a solution of ligand 7a-Pr (75.0 mg, 78 μmol, 1.0 equiv) in dry DCM via syringe. The nickel salen complex 8a-Pd was isolated as a brown solid (80.1 mg, 75 μmol, 96%). C42H60I2N8O2Pd: mol wt 1069.22 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 9.06 (s, 2H, CHN), 7.99 (s, 2H, H−trz), 7.63 (d, J = 2.6, 2H, H−Ar), 7.52 (d, J = 2.6, 2H, H−Ar), 6.05 (d, J = 13.9, 2H, Ar−CH2−Ntrz), 5.59 (d, J = 13.9, 2H, Ar−CH2−Ntrz), 4.17 (s, 6H, Ntrz−CH3), 3.54 (b, 2H, CHCyhex), 2.78 (m, 4H, CH2−CH2−CH3), 2.03 (b, 2H, (CH2)Cyhex), 1.96 (b, 2H, (CH2)Cyhex), 1.71 (q, J = 7.5, 4H CH2−CH2−CH3), 1.46 (b, 4H, (CH2)Cyhex) 1.32 (s, 18H, (CH3)3), 0.93 (t, J = 7.5, 6H, CH2− CH2−CH3). 13C NMR (CD2Cl2, 125 MHz, 21 °C): δ 161.4 (2C, CAr−OPd), 157.1 (2C, Ctrz−nPr), 144.1 (2C, CAr−tBu), 138.4 (2C, CAr), 135.1 (2C, CAr), 134.0 (2C, Ctrz−H), 130.4 (2C, CHN), 122.9 (2C, CAr), 121.8 (2C, CAr), 73.0 (2C, CHCyhex), 56.6 (2C, Ar−CH2− Ntrz), 38.2 (2C, Ntrz−CH3), 34.2 (2C, CtBu), 31.4 (6C, CtBu), 29.5 (2C, (CH2)Cyhex), 25.9 (2C, CH2−CH2−CH3), 24.8 (2C, (CH2)Cyhex), 20.7 (2C, CH2−CH2−CH3), 14.0 (2C, CH2−CH2−CH3). IR (in CD2Cl2): ν̃ 2956, 1718, 1621, 1543, 1453, 1317, 1220, 1037, 707, 527. HRMS (ESI): m/z calcd for [C42H60N8O2PdI+], 941.2928; found, 941.2945. −1 Mp: 157 °C dec. [α]20 D (c = 1.00 mg mL , DCM): −167.7. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[3-methyl-4propyl-1H-1,2,3-triazol-1-yl-3-ium]](2−)]palladium(II)} Tetrafluoroborate (8b-Pd). The palladium(II) complex 8b-Pd was synthesized according to GP3 using Pd(OAc)2 (17.5 mg, 78 μmol, 1.0 equiv) and sodium acetate (12.8 mg, 155 μmol, 2.0 equiv) as base. To this suspension a solution of ligand 7b-Pr (75.0 mg, 78 μmol, 1.0 equiv) in dry DCM was added via syringe. The nickel-salen complex 8b-Pd was isolated as a yellow solid (80.1 mg, 75 μmol, 96%). C42H60B4F8N8O2Pd: mol wt 988.02 g mol−1. 1H NMR (CD2Cl2, 700 MHz, 21 °C): δ 9.06 (s, 2H, CHN), 7.99 (s, 2H, H−trz), 7.63 (d, J = 2.6, 2H, H−Ar), 7.52 (d, J = 2.6, 2H, H−Ar), 6.05 (d, J = 13.9, 2H,

Mes (500.0 mg, 1.0 mmol, 2.0 equiv) and molecular sieves were diluted with degassed ethanol, and (1R,2R)-(−)-1,2-diaminocyclohexane (59.6 mg, 0.5 mmol, 1.0 equiv) was added as a solution in ethanol via syringe. After precipitation from diethyl ether 7-Mes was isolated as a yellow solid (509.9 mg, 0.5 mmol, 94%). C54H70B2F8N8O2: mol wt 1036.82 g mol−1. 1H NMR (CDCl3, 300 MHz, 21 °C): δ 14.09 (s, 2H, OH), 8.38 (s, 2H, CHN), 8.34 (s, 2H, H−trz), 7.56 (d, J = 2.3, 2H, H−Ar), 7.33 (d, J = 2.3, 2H, H−Ar), 7.05 (d, J = 3.4, 4H, H− Mes), 5.90 (d, J = 14.3, 2H, Ar−CH2−Ntrz), 5.72 (d, J = 14.3, 2H, Ar− CH2−Ntrz), 3.92 (s, 6H, Ntrz−CH3), 3.65 (m, 2H, CHCyhex), 3.40 (m, 2H, CHCyhex), 2.36 (s, 6H,(p−CH3)Mes), 1.99 (d, 12H, (o-CH3)Mes), 1.56 (m, 6H, (CH2)Cyhex, 1.27 (s, 18H, (CH3)3). 13C NMR (CDCl3, 75 MHz, 21 °C): δ 164.8 (2C, CAr−OH), 158.7 (2C, Ctrz−Mes), 142.6 (2C, CAr−tBu), 141.7 (2C, CAr), 141.5 (2C, CAr), 138.3 (4C, CMes), 131.7 (2C, CMes), 130.3 (2C, CAr), 130.1 (2C, Ctrz−H) 129.3 (2C, CHN), 129.2 (2C, CHMes), 128.7 (2C, CHMes), 128.2 (2C, CMes), 127.6 (2C, CAr), 71.6 (2C, CHCyhex), 55.5 (2C, Ar−CH2−Ntrz), 37.4 (2C, Ntrz−CH3), 34.0 (2C, CtBu), 32.9 (2C, (CH2)Cyhex), 31.0 (6C, CtBu), 24.0 (2C, (CH2)Cyhex), 21.0 (2C, (CH3)Mes), 19.6 (2C, (CH3)Mes), 19.5 (2C, (CH3)Mes). 19F NMR (CDCl3, 235 MHz, 21 °C): δ −152.5. IR (solid): ν̃ 2952, 2864, 1639, 1480, 1364, 1282, 1225, 1030, 853, 798, 713, 658, 576, 519. HRMS (ESI): m/z calcd for [C54H70N8O2BF4+]: 949.5654; found, 949.5650. Mp: 148−150 °C −1 dec. [α]20 D (c = 1.05 mg mL , DCM): −242.5. Preparation of the Salen-Metal Complexes. {[1,1′-[(1R,2R)1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[3-methyl-4-propyl-1H1,2,3-triazol-1-yl-3-ium]](2−)]nickel(II)} Iodide (8a-Ni). The nickel(II) complex 8a-Ni was synthesized according to GP3 using Ni(Cp)2 (18.3 mg, 97 μmol, 1.0 equiv) and a solution of ligand 7a-Pr (93.5 mg, 97 μmol, 1.0 equiv) in dry DCM. The nickel salen complex 8a-Ni was isolated as a red-brown solid (90.2 mg, 88 μmol, 92%). C42H60I2N8O2Ni: mol wt 1021.50 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 9.12 (s, 2H, CHN), 7.63 (s, 2H, H−trz), 7.48 (d, J = 2.3, 2H, H−Ar), 7.40 (d, J = 2.3, 2H, H−Ar), 5.86 (d, J = 13.8, 2H, Ar−CH2−Ntrz), 5.41 (d, J = 13.8, 2H, Ar−CH2−Ntrz), 4.16 (s, 6H, Ntrz−CH3), 3.15 (b, 2H, CHCyhex), 2.78 (t, J = 7.8, 4H, CH2−CH2− CH3), 2.55 (b, 2H, (CH2)Cyhex), 1.96 (b, 2H, (CH2)Cyhex), 1.68 (q, J = 7.8, 4H CH2−CH2−CH3), 1.40 (b, 4H, (CH2)Cyhex) 1.29 (s, 18H, (CH3)3), 0.97 (t, J = 7.8, 6H, CH2−CH2−CH3). 13C NMR (CD2Cl2, 125 MHz, 21 °C): δ 159.8 (2C, CAr−ONi), 158.7 (2C, Ctrz−nPr), 144.1 (2C, CAr−tBu), 138.4 (2C, CAr), 133.9 (2C, CAr), 131.7 (2C, Ctrz−H), 130.0 (2C, CHN), 121.8 (2C, CAr), 121.7 (2C, CAr), 70.3 (2C, CHCyhex), 56.2 (2C, Ar−CH2−Ntrz), 38.0 (2C, Ntrz−CH3), 33.8 (2C, CtBu), 31.1 (6C, CtBu), 29.1 (2C, (CH2)Cyhex), 24.3 (4C, CH2− CH2−CH3), 20.3 (2C, CH2−CH2−CH3), 13.4 (2C, CH2−CH2− CH3). IR (solid): ν̃ 3436, 3094, 1618, 1549, 1454, 1223, 1073, 834, 594. HRMS (ESI): m/z calcd for [C36H49N5O2Ni2+], 320.6614; found, −1 320.6623. Mp: 160−163 °C dec. [α]20 D (c = 1.05 mg mL , DCM): −619.2. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[3-methyl-4propyl-1H-1,2,3-triazol-1-yl-3-ium]](2−)]nickel(II)} Tetrafluoroborate (8b-Ni). The nickel(II) complex 8b-Ni was synthesized according to GP3 using Ni(Cp)2 (18.3 mg, 97 μmol, 1.0 equiv) and a solution of ligand 7b-Pr (93.5 mg, 97 μmol, 1.0 equiv) in dry DCM. The nickel salen complex 8b-Ni was isolated as a red-brown solid (90.2 mg, 88 μmol, 92%). C42H60B2F8N8O2Ni: mol wt 941.30 g mol−1. 1H NMR (CD2Cl2, 500 MHz, 21 °C): δ 9.12 (s, 2H, CHN), 7.63 (s, 2H, H− trz), 7.48 (d, J = 2.3, 2H, H−Ar), 7.40 (d, J = 2.3, 2H, H−Ar), 5.86 (d, J = 13.8, 2H, Ar−CH2−Ntrz), 5.41 (d, J = 13.8, 2H, Ar−CH2−Ntrz), 4.16 (s, 6H, Ntrz−CH3), 3.15 (b, 2H, CHCyhex), 2.78 (t, J = 7.8, 4H, CH2−CH2−CH3), 2.55 (b, 2H, (CH2)Cyhex), 1.96 (b, 2H, (CH2)Cyhex), 1.68 (q, J = 7.8, 4H CH2−CH2−CH3), 1.40 (b, 4H, (CH2)Cyhex) 1.29 (s, 18H, (CH3)3), 0.97 (t, J = 7.8, 6H, CH2−CH2−CH3). 13C NMR (CD2Cl2, 125 MHz, 21 °C): δ 160.2 (2C, CAr−ONi), 159.1 (2C, Ctrz− nPr), 144.4 (2C, CAr−tBu), 138.9 (2C, CAr), 134.3 (2C, CAr), 132.0 (2C, Ctrz−H), 129.4 (2C, CHN), 122.3 (2C, CAr), 121.0 (2C, CAr), 70.7 (2C, CHCyhex), 55.2 (2C, Ar−CH2−Ntrz), 37.5 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.4 (6C, CtBu), 29.2 (2C, (CH2)Cyhex), 25.5 (2C, H


Article

Organometallics Ar−CH2−Ntrz), 5.59 (d, J = 13.9, 2H, Ar−CH2−Ntrz), 4.17 (s, 6H, Ntrz−CH3), 3.54 (b, 2H, CHCyhex), 2.78 (m, 4H, CH2−CH2−CH3), 2.03 (b, 2H, (CH2)Cyhex), 1.96 (b, 2H, (CH2)Cyhex), 1.71 (q, J = 7.5, 4H CH2−CH2−CH3), 1.46 (b, 4H, (CH2)Cyhex), 1.32 (s, 18H, (CH3)3), 0.93 (t, J = 7.5, 6H, CH2−CH2−CH3). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 166.4 (2C, Ccarbene), 160.7 (2C, CAr−OPd), 159.7 (2C, Ctrz− nPr), 148.5 (2C, CAr−tBu), 137.4 (2C, CAr), 135.2 (2C, CAr), 130.4 (2C, CAr), 124.3 (2C, CHN), 120.5 (2C, CAr), 70.4 (2C, CHCyhex), 54.6 (2C, Ar−CH2−Ntrz), 36.4 (2C, Ntrz−CH3), 34.0 (2C, CtBu), 31.4 (6C, CtBu), 29.2 (1C, (CH2)Cyhex), 27.8 (1C, (CH2)Cyhex), 25.5 (2C, CH2−CH2−CH3), 24.7 (1C, (CH2)Cyhex), 23.5 (1C, (CH2)Cyhex) 22.7 (2C, CH2−CH2−CH3), 14.2 (2C, CH2−CH2−CH3). 19F NMR (CD2Cl2, 376 MHz, 21 °C): δ −153.5. IR (solid): ν̃ 2951, 2867, 1620, 1543, 1450, 1315, 1219, 1031, 832, 734, 552, 520. HRMS (ESI): m/z calcd for [C30H38N2O2Pd+], 565.2052; found, 565.2048. Mp: −1 165−169 °C. [α]20 D (c = 1.10 mg mL , DCM): −441.0. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[4-mesityl-3methyl-1H-1,2,3-triazol-1-yl-3-ium]](2−)]nickel(II)} Tetrafluoroborate (9-Pd). The palladium(II) complex 9-Pd was synthesized according to GP3 using Pd(OAc)2 (16.2 mg, 72 μmol, 1.0 equiv) and sodium acetate (11.9 mg, 145 μmol, 2.0 equiv) as base. To this suspension was added a solution of ligand 7-Mes (75.0 mg, 72 μmol, 1.0 equiv) in dry DCM via syringe. The nickel-salen complex 9-Pd was isolated as a brown solid (75.5 mg, 66 μmol, 92%). C54H68B2F4N8O2Pd: mol wt 1141.22 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 8.75 (s, 2H, CHN), 7.89 (s, 2H, H−trz), 7.49 (d, J = 2.5, 2H, H−Ar), 7.44 (d, J = 2.5, 2H, H−Ar), 6.98 (s, 2H, H−Mes), 6.88 (s, 2H, H−Mes), 5.66 (d, J = 14.1, 2H, Ar−CH2−Ntrz), 5.40 (d, J = 14.1, 2H, Ar−CH2−Ntrz), 3.93 (s, 6H, Ntrz−CH3), 3.45 (b, 2H, (CH2)Cyhex), 2.70 (b, 2H, CHCyhex), 2.28 (s, 6H, (p−CH3)Mes), 2.11 (s, 6H, (o-CH3)Mes), 2.03 (s, 6H, (o-CH3)Mes, 1.59 (b, 2H, (CH2)Cyhex), 1.43 (b, 4H, (CH2)Cyhex), 1.31 (s, 18H, (CH3)3). 13C NMR (CD2Cl2, 125 MHz, 21 °C): δ 161.4 (2C, CAr−OPd), 157.0 (2C, Ctrz−Mes), 142.7 (2C, CAr−tBu), 141.1 (2C, CAr), 139.2 (2C, CAr), 138.9 (2C, CMes), 138.5 (2C, CMes), 135.0 (2C, CAr), 133.9 (2C, Ctrz−H) 131.8 (2C, CHN), 129.5 (2C, CHMes), 129.3 (2C, CHMes), 122.8 (2C, CMes), 121.6 (2C, CAr), 119.0 (2C, CMes), 73.1 (2C, CHCyhex), 56.0 (2C, Ar−CH2−Ntrz), 37.6 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.4 (6C, CtBu), 29.2 (2C, (CH2)Cyhex), 24.8 (2C, (CH2)Cyhex), 21.4 (2C, (CH3)Mes), 20.2 (2C, (CH3)Mes), 20.1 (2C, (CH3)Mes). 19F NMR (CDCl3, 235 MHz, 21 °C): δ −152.8. IR (in CD2Cl2): ν̃ 2952, 1624, 1545, 1452, 1219, 1033, 674. HRMS (ESI): m/z calcd for [C54H68N8O2PdBF4+], 1053.4549; found, 1053.4555. Mp: >200 °C −1 dec. [α]20 D (c = 1.00 mg mL , DCM): −128.7. Preparation of the MIC-Metal Complexes. {[1,1′-[(1R,2R)-1,2Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxyκO)-3,1-phenylene]methylene]bis[4-propyl-3-methyl-1,2,3-triazol1-yl-3-ium-5-ylidene]]]nickel(II)silver(I)} Dichloroargentate (10-Ni). Complex 10-Ni was prepared according to GP4 using nickel salen 8bNi (20.0 mg, 21.2 μmol, 1.0 equiv), silver(I) oxide (24.9 mg, 106.2 μmol, 5.0 equiv), predried potassium chloride (10.3 mg, 85.0 μmol, 4 equiv), and cesium carbonate (41.5 mg, 127.5 μmol, 6.0 equiv). 10-Ni was obtained as a light green solid (20.7 mg, 19.7 μmol, 93%). C42H58Cl2N8O2NiAg2: mol wt1052.31 g mol−1. 1H NMR (CD2Cl2, 700 MHz, 21 °C): δ 7.73 (s, 2H, CHN), 7.45 (b, 2H, H−Ar), 7.18 (b, 2H, H−Ar), 5.68 (s, 4H, Ar−CH2−Ntrz), 4.00 (s, 6H, Ntrz−CH3), 3.05 (b, 2H, CHCyhex), 2.74 (b, 4H, CH2−CH2−CH3), 2.42 (b, 2H, (CH2)Cyhex), 1.91 (b, 2H, (CH2)Cyhex), 1.80 (q, J = 7.3, 4H, CH2− CH2−CH3), 1.71 (b, 2H, (CH2)Cyhex), 1.30 (s, 18H, (CH3)3), 1.04 (t, J = 7.3, 6H, CH2−CH2−CH3), 0.88 (b, 2H, (CH2)Cyhex). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 166.4 (2C, Ccarbene), 160.7 (2C, CAr− ONi), 159.7 (2C, Ctrz−nPr), 148.5 (2C, CAr−tBu), 137.4 (2C, CAr), 135.2 (2C, CAr), 130.4 (2C, CAr), 124.3 (2C, CHN), 120.5 (2C, CAr), 70.4 (2C, CHCyhex), 54.6 (2C, Ar−CH2−Ntrz), 36.4 (2C, Ntrz− CH3), 34.0 (2C, CtBu), 31.4 (6C, CtBu), 29.2 (1C, (CH2)Cyhex), 27.8 (1C, (CH2)Cyhex), 25.5 (2C, CH2−CH2−CH3), 24.7 (1C, (CH2)Cyhex), 23.5 (1C, (CH2)Cyhex) 22.7 (2C, CH2−CH2−CH3), 14.2 (2C, CH2− CH2−CH3). IR (solid): ν̃ 2949, 2862, 1619, 1542, 1448, 1310, 1260, 1058, 850, 818, 732, 548, 520. HRMS (ESI): m/z calcd for

[C42H58N8O2NiAg+]: 873.3072; found, 873.3043. Mp: >220 °C dec. −1 [α]20 D (c = 0.75 mg mL , DCM): −244.4. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[4-mesityl-3methyl-1,2,3-triazol-1-yl-3-ium-5-ylidene]]]nickel(II)silver(I)} Dichloroargentate (11-Ni). Complex 11-Ni was prepared according to GP4 using nickel salen 9-Ni (20.0 mg, 18.3 μmol, 1.0 equiv), silver(I) oxide (4.3 mg, 18.3 μmol, 1.0 equiv), and dry potassium tert-butoxide (6.7 mg, 54.9 μmol, 3.0 equiv). 11-Ni was obtained as an orange solid (22.1 mg, 16.9 μmol, 92%). C54H66Cl2N8O2NiAg2: mol wt 1204.51 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 7.78 (s, 2H, CHN), 7.74 (b, 2H, H−Ar), 7.20 (b, 2H, H−Ar), 6.99 (b, 4H, H−Mes) 6.80 (b, 2H, Ar−CH2−Ntrz), 5.78 (b, 2H, Ar−CH2−Ntrz), 3.71 (s, 6H, Ntrz−CH3), 3.04 (b, 4H, (CH2)Cyhex), 2.39 (b, 6H,(p−CH3)Mes), 1.96 (b, 2H, CHCyhex), 1.92 (b, 12H, (o-CH3)Mes), 1.69 (b, 4H, (CH2)Cyhex), 1.30 (s, 18H, (CH3)3). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 165.9 (2C, Ccarbene), 160.2 (2C, CAr−ONi), 159.1 (2C, Ctrz−Mes), 142.7 (2C, CAr−tBu), 141.6 (2C, CAr), 139.1 (2C, CAr), 138.8 (1C, CMes), 138.6 (1C, CMes), 134.1 (2C, CAr), 132.1 (2C, CMes) 131.0 (2C, CH N), 129.6 (2C, CHMes), 129.4 (2C, CHMes), 122.1 (2C, CMes), 120.9 (2C, CAr), 118.4 (2C, CMes), 70.8 (2C, CHCyhex), 55.5 (2C, Ar−CH2− Ntrz), 37.5 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.4 (6C, CtBu), 29.3 (2C, (CH2)Cyhex), 24.6 (2C, (CH2)Cyhex), 21.4 (2C, (CH3)Mes), 20.3 (2C, (CH3)Mes), 20.0 (2C, (CH3)Mes). IR (solid): ν̃ 2949, 2863, 1619, 1548, 1453, 1312, 1261, 1221, 1054, 850, 818, 736, 553, 520. HRMS (ESI): m/z calcd for [C54H66N8O2NiAg+], 1025.3702; found, 1025.3691. Mp: −1 >220 °C dec. [α]20 D (c = 1.05 mg mL , DCM): −323.4. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[4-propyl-3methyl-1,2,3-triazol-1-yl-3-ium-2-ylidene]]]palladium(II)silver(I)} Dichloroargentate (10-Pd). Complex 10-Pd was prepared according to GP4 using palladium salen 8b-Pd (20.0 mg, 19.6 μmol, 1.0 equiv), silver(I) oxide (4.6 mg, 19.6 μmol, 1.0 equiv), and dry potassium tertbutoxide (7.1 mg, 58.7 μmol, 3.0 equiv). 10-Pd was obtained as a yellow solid (19.8 mg, 15.4 μmol, 83%). C42H58Cl2N8O2PdAg2: mol wt 1064.59 g mol−1. 1H NMR (CD2Cl2, 700 MHz, 21 °C): δ 7.85 (d, J = 2.6, 2H, H−Ar), 7.80 (s, 2H, CHN), 7.32 (d, J = 2.5, 2H, H−Ar), 5.88 (d, J = 13.3, 2H, Ar−CH2−Ntrz), 5.68 (d, J = 13.3, 2H, Ar−CH2− Ntrz), 3.98 (s, 6H, Ntrz−CH3), 3.42 (b, 2H, CHCyhex), 2.77 (t, J = 7.7, 4H, CH2−CH2−CH3), 2.65 (b, 2H, CHCyhex), 1.99 (b, 4H, (CH2)Cyhex), 1.80 (q, J = 7.7, 4H CH2−CH2−CH3), 1.56 (b, 2H, CHCyhex), 1.35 (s, 18H, (CH3)3), 1.05 (t, J = 7.5, 6H, CH2−CH2− CH3). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 166.8 (2C, Ccarbene), 160.7 (2C, CAr−OPd), 158.6 (2C, Ctrz−nPr), 148.4 (2C, CAr−tBu), 137.4 (2C, CAr), 135.6 (2C, CAr), 130.4 (2C, CAr), 124.3 (2C, CH N), 120.5 (2C, CAr), 70.5 (2C, CHCyhex), 54.7 (2C, Ar−CH2−Ntrz), 36.6 (2C, Ntrz−CH3), 34.0 (2C, CtBu), 31.4 (6C, CtBu), 29.2 (1C, (CH2)Cyhex), 27.9 (1C, (CH2)Cyhex), 25.4 (2C, CH2−CH2−CH3), 24.7 (1C, (CH2)Cyhex), 23.6 (1C, (CH2)Cyhex) 21.7 (2C, CH2−CH2−CH3), 14.2 (2C, CH2−CH2−CH3). IR (solid): ν̃ 2952, 2869, 1620, 1542, 1449, 1312, 1218, 1037, 833, 734, 552, 520. HRMS (ESI): m/z calcd for [C42H58N8O2PdAg+], 921.2775; found, 921.2771. Mp: 210 °C dec. −1 [α]20 D (c = 1.20 mg mL , DCM): −155.5. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[4-mesityl-3methyl-1,2,3-triazol-1-yl-3-ium-5-ylidene]]]palladium(II)silver(I)} Dichloroargentate (11-Pd). Complex 11-Pd was prepared according to GP4 using palladium salen 9-Pd (20.0 mg, 17.5 μmol, 1.0 equiv), silver(I) oxide (4.1 mg, 17.5 μmol, 1.0 equiv), and dry potassium tertbutoxide (6.4 mg, 52.6 μmol, 3.0 equiv). 11-Pd was obtained as an orange solid (21.8 mg, 16.1 μmol, 92%). C54H66Cl2N8O2PdAg2: mol wt 1252.23 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 7.83 (b, 2H, CHN), 7.51−7.32 (b, 2H, H−Ar), 7.00 (b, 4H, H−Mes), 6.86 (b, 4H, H−Ar), 5.84 (b, 2H, Ar−CH2−Ntrz), 3.72 (s, 6H, Ntrz−CH3), 3.47 (b, 2H, CHCyhex), 2.36 (b, 6H,(p−CH3)Mes), 1.96 (b, 12H, (oCH3)Mes), 1.84 (b, 2H, CHCyhex), 1.72 (b, 4H, (CH2)Cyhex), 1.58 (b, 2H, CHCyhex), 1.33 (b, 18H, (CH3)3). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 168.3 (2C, Ccarbene), 160.2 (2C, CAr−OPd), 159.1 (2C, Ctrz− Mes), 142.7 (2C, CAr−tBu), 141.6 (1C, CMes), 139.1 (1C, CMes), 138.8 (1C, CAr), 138.6 (1C, CAr), 134.1 (2C, CAr), 132.1 (2C, CAr) 131.0 (2C, CHN), 129.6 (1C, CHMes), 129.4 (1C, CHMes), 122.1 (2C, I


Article

Organometallics

−1 >220 °C. [α]20 D (c = 0.90 mg mL , DCM): −497.7. Anal. Calcd for C54H66Cl6N8O2PdAu2: C, 41.25; H, 4.23; N, 7.13. Found: C, 41.02; H, 4.12; N, 6.99. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]nickel(II)bis[4p rop yl-3-met hyl-1,2,3-tri azol -1 -yl -3 -i um-2-ylid ene] ]] μiodobispalladium(II)} Iodide (13-Ni). To synthesize Ni salen Pd MIC complex 13-Ni, Ni complex 8a-Ni (13.0 mg, 12 μmol, 1.0 equiv) was added to palladium acetate (6.0 mg, 27 μmol, 2.2 equiv), sodium iodide (4.0 mg, 27 μmol, 2.2 equiv), and molecular sieves 4 Å as a solution in dry DCM. The reaction mixture was stirred at 30 °C under an inert gas atmosphere for 15 h to yield the desired complex 13-Ni as a brown solid (15.1 mg, 10 μmol, 80%). C42H58I4N8O2Pd2Ni: mol wt 1486.13 g mol−1. 1H NMR (CD2Cl2, 300 MHz, 21 °C): δ 9.02 (s, 1H, CHN), 8.05 (b, 1H, CHN), 7.58−7.16 (b, 4H, H−Ar), 5.83 (b, 4H, Ar−CH2−Ntrz), 4.64 (s, 1H, CHCyhex), 4.19 (b, 3H, CHCyhex), 4.01. (b, 6H, Ntrz−CH3), 3.12 (b, 2H, (CH2)Cyhex), 2.81 (b, 4H, CH2−CH2− CH3), 2.51 (b, 2H, (CH2)Cyhex), 1.95 (b, 4H, CH2−CH2−CH3), 1.72 (b, 2H, (CH2)Cyhex), 1.27, 1.25 (s, 2*9H, (CH3)3), 0.84 (b, 6H, CH2− CH2−CH3). 13C NMR (MeCN-d3, 176 MHz, 21 °C): δ 158.8 (2C, Ccarbene), 158.2 (2C, CAr−OPd), 143.5 (2C, Ctrz−nPr), 140.0 (2C, CAr−tBu), 132.7 (2C, CAr), 130.6 (2C, CAr), 128.2 (2C, CAr), 121.3 (2C, CHN), 119.8 (2C, CAr), 69.8 (2C, CHCyhex), 53.6 (2C, Ar− CH2−Ntrz), 36.7 (2C, Ntrz−CH3), 32.7 (2C, CtBu), 30.1 (6C, CtBu), 29.9 (2C, (CH2)Cyhex), 29.7 (2C, (CH2)Cyhex), 27.7 (2C, CH2−CH2− CH3), 24.0 (1C, (CH2)Cyhex), 23.2 (1C, (CH2)Cyhex) 19.1 (2C, CH2− CH2−CH3), 11.9 (2C, CH2−CH2−CH3). IR (solid): ν̃ 2950, 2860, 1720, 1548, 1451, 1311, 1220, 1044, 829, 529. HRMS (ESI): m/z calcd for [C42H58N8O2NiPd2+], 435.1535; found, 435.1532, calcd for [C39H49N5O2I2NiPd+]: 1003.0353; found, 1003.0312 and calcd for [C42H58N8O2I4NiPd+2 ]: 1484.8296; found, 1484.0112 (overlay of −1 different fragments). Mp: 169−171 °C. [α]20 D (c = 0.9 mg mL , DCM): −306.8. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]palladium(II)bis[4p rop yl-3-met hyl-1,2,3-tri azol -1 -yl -3 -i um-2-ylid ene] ]] μiodobispalladium(II) Iodide (14-Pd). To synthesize Pd salen Pd MIC complex 14-Pd, Pd complex 8a-Pd (10.0 mg, 9 μmol, 1.0 equiv) was added to palladium acetate (4.6 mg, 21 μmol, 2.2 equiv), sodium iodide (3.1 mg, 21 μmol, 2.2 equiv), and molecular sieves 4 Å as a solution in dry DCM. The reaction mixture was stirred at 30 °C under an inert gas atmosphere for 15 h to yield the desired complex 14-Pd as a brown solid (12.6 mg, 8 μmol, 88%). A single crystal suitable for Xray analysis was obtained by slow diffusion of n-hexanes into a solution of the complex in a mixture of DCE/toluene 10/1 at 7 °C. C42H58I4N8O2Pd3: mol wt 1533.86 g mol−1. 1H NMR (CD2Cl2, 300 MHz, 21 °C): δ 8.88 (s, 1H, CHN), 8.07 (s, 2H, CHN), 7.92−7.31 (b, 4H, H−Ar), 5.93 (b, 2H, Ar−CH2−Ntrz), 5.64 (b, 2H, Ar−CH2−Ntrz), 4.65 (b, 2H, CHCyhex), 4.16 (b, 2H, CHCyhex), 3.99 (b, 6H, Ntrz−CH3), 3.51. (b, 4H, CH2−CH2−CH3), 2.71 (b, 4H, (CH2)Cyhex), 1.94 (b, 4H, CH2−CH2−CH3), 1.60 (b, 2H, (CH2)Cyhex), 1.32, 1.26 (s, 2*9H, (CH3)3), 0.86 (b, 6H, CH2−CH2−CH3). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 161.6 (2C, Ccarbene), 156.9 (2C, CAr−OPd), 145.0 (2C, Ctrz−nPr), 144.3 (2C, CAr−tBu), 138.5 (2C, CAr), 135.6 (1C, CAr), 133.4 (1C, CAr), 130.2 (2C, CHN), 123.4 (2C, CAr), 121.5 (2C, CAr), 73.0 (2C, CHCyhex), 55.9 (2C, Ar−CH2−Ntrz), 37.8 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.4 (6C, CtBu), 29.9 (1C, (CH2)Cyhex), 29.2 (1C, (CH2)Cyhex), 27.5 (2C, CH2−CH2−CH3), 25.8 (1C, (CH2)Cyhex), 24.5 (1C, (CH2)Cyhex), 22.3 (1C, (CH2)Cyhex), 20.5 (2C, CH2−CH2−CH3), 13.8 (2C, CH2−CH2−CH3). IR (solid): ν̃ 2958, 2927, 2867, 1726, 1624, 1552, 1416, 1324, 1263, 1037, 432, 693, 553. HRMS (ESI): m/z calcd for [C42H58N8O2I4Pd3]Na+, 1556.7890; found, 1556.7832; calcd for [C42H58N8O2I3Pd3+], 1406.8948; found, −1 1406.8939. Mp: 180 °C. [α]20 D (c = 0.6 mg mL , DCM): −408.2. Catalytic 1,4-Addition of N-Boc-3-Methyloxindole to transβ-Nitrostyrene.10 The Michael addition was performed according to the literature protocol reported by Peters et al.10 N-Boc-oxindole (E-5; 24.7 mg, 0.10 mmol, 2.0 equiv) and trans-β-nitrostyrene (E-4; 7.5 mg, 0.05 mmol, 1.0 equiv) were weighed into a 500 μL reaction tube flask equipped with a magnetic stirring bar. Then the solid catalyst was

CMes), 120.9 (2C, CAr), 118.4 (2C, CMes), 70.8 (2C, CHCyhex), 55.5 (2C, Ar−CH2−Ntrz), 37.5 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.4 (6C, CtBu), 29.3 (2C, (CH2)Cyhex), 24.6 (2C, (CH2)Cyhex), 21.4 (2C, (CH3)Mes), 20.3 (2C, (CH3)Mes), 20.0 (2C, (CH3)Mes). IR (solid): ν̃ 2949, 2863, 1618, 1542, 1448, 1311, 1035, 850, 818, 733, 548, 520. HRMS (ESI): m/z calcd for [C54H68N8O2PdAg+], 1073.3405; found, −1 1073.3434. Mp: > 220 °C dec. [α]20 D (c = 1.05 mg mL , DCM): −145.0. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[4-mesityl-3methyl-1,2,3-triazol-1-yl-3-ium-5-ylidene]]]nickel(II)bisgold(III)} Chloride (12-Ni). Complex 12-Ni was prepared according to GP5 using Ni−Ag complex 11-Ni (20.0 mg, 17 μmol, 1.0 equiv) and gold(I) chloride dimethyl sulfide (10.3 mg, 35 μmol, 2.1 equiv). After filtration and precipitation a mixture of different gold(I)-MIC species was obtained as an orange solid (92% yield), which was then oxidized with PhICl2 (4.2 mg, 15 μmol, 2.1 equiv), yielding the corresponding Au(III) species as an orange solid (17.0 mg, 11.2 μmol, 65% over two steps). A single crystal suitable for X-ray analysis was obtained by slow diffusion of n-pentane into a solution of the complex in 1,2dichloroethane. C54H66Cl6N8O2NiAu2: mol wt 1524.50 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 7.55 (d, J = 2.3, 2H, H−Ar), 7.41 (s, 2H, CHN), 7.28 (d, J = 2.3, 2H, H−Ar), 7.02 (s, 2H, H−Mes), 6.97 (s, 2H, H−Mes), 6.07 (d, J = 13.0, 2H, Ar−CH2−Ntrz), 5 63 (d, J = 13.0, 2H, Ar−CH2−Ntrz), 3.69 (s, 6H, Ntrz−CH3), 2.83 (b, 2H, CHCyhex), 2.45 (s, 6H,(p−CH3)Mes), 2.39 (b, 2H, CHCyhex), 2.33 (s, 6H, (o-CH3)Mes), 2.18 (s, 6H, (o-CH3)Mes), 1.87 (b, 3H, (CH2)Cyhex), 1.31 (s, 18H, (CH3)3), 1.27 (b, 3H, CHCyhex). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 161.3 (2C, Ccarbene), 161.1 (2C, CAr−ONi), 159.7 (2C, Ctrz−Mes), 142.3 (2C, CAr−tBu), 142.0 (2C, CAr), 139.8 (1C, CAr), 139.2 (1C, CMes), 137.8 (2C, CMes), 135.5 (2C, CAr), 131.4 (2C, CAr) 131.2 (2C, CHN), 129.4 (2C, CHMes), 129.2 (2C, CHMes), 121.7 (2C, CMes), 121.0 (2C, CMes), 120.8 (2C, CMes), 70.1 (2C, CHCyhex), 56.7 (2C, Ar−CH2−Ntrz), 37.1 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.6 (6C, CtBu), 29.1 (2C, (CH2)Cyhex), 24.6 (2C, (CH2)Cyhex), 21.4 (2C, (CH3)Mes), 20.2 (2C, (CH3)Mes), 20.8 (2C, (CH3)Mes). IR (solid): ν̃ 2950, 2862, 2168, 1618, 1546, 1451, 1335, 1222, 1045, 851, 820, 736, 556, 520. HRMS (ESI): m/z calcd for [C54H68N8O2NiAuCl2+], 1185.3679; found, 1185,3710. Mp: >220 −1 °C. [α]20 D (c = 0.85 mg mL , DCM): −644.9. Anal. Calcd for C54H66Cl6N8O2NiAu2·1.0(DCE) (in accordance with crystal structure): C, 41.43; H, 4.35; N, 6.90. Found: C, 41.07; H, 4.21; N, 7.15. {[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN-[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[4-mesityl-3methyl-1,2,3-triazol-1-yl-3-ium-5-ylidene]]]palladium(II)bisgold(III)} Chloride (12-Pd). Complex 12-Pd was prepared according to GP5 using Ni−Ag complex 11-Pd (20 mg, 16 μmol, 1.0 equiv) and gold(I) chloride dimethyl sulfide (9.9 mg, 34 μmol, 2.1 equiv). After filtration and precipitation a mixture of different gold(I)-MIC species was obtained as an orange solid (88% yield), which was oxidized by PhICl2 (5.7 mg, 21 μmol, 2.1 equiv) to yield the Au(III)-MIC complex as a yellow solid (19.4 mg, 12 μmol, 75% over 2 steps). C54H66Cl6N8O2PdAu2: mol wt 1430.43 g mol−1. 1H NMR (CD2Cl2, 400 MHz, 21 °C): δ 7.70 (s, 2H, CHN), 7.57 (d, J = 2.9, 2H, H−Ar), 7.32 (d, J = 2.9, 2H, H−Ar), 6.91 (s, 2H, H−Mes), 6.86 (s, 2H, H− Mes), 6.04 (d, J = 14.5, 2H, Ar−CH2−Ntrz), 5 74 (d, J = 14.5, 2H, Ar− CH2−Ntrz), 3.76 (s, 6H, Ntrz−CH3), 3.21 (b, 2H, CHCyhex), 2.95 (b, 1H, CHCyhex), 2.53 (b, 2H, CHCyhex), 2.23 (s, 6H,(p−CH3)Mes), 2.08 (s, 6H, (o-CH3)Mes), 2.05 (s, 6H, (o-CH3)Mes), 1.88 (b, 3H, CHCyhex), 1.26 (s, 18H, (CH3)3), 0.78 (b, 2H, CHCyhex). 13C NMR (CD2Cl2, 176 MHz, 21 °C): δ 162.4 (2C, Ccarbene), 156.3 (2C, CAr−OPd), 154.3 (2C, Ctrz−Mes), 142.3 (2C, CAr−tBu), 139.6 (1C, CAr), 139.1 (1C, CAr), 137.8 (2C, CAr), 136.2 (2C, CMes), 133.4 (2C, CMes), 131.7 (2C, CMes), 129.4 (2C, CMes) 122.3 (2C, CHN), 122.0 (2C, CMes), 120.6 (2C, CMes), 72.5 (2C, CHCyhex), 56.7 (2C, Ar−CH2−Ntrz), 37.6 (2C, Ntrz−CH3), 34.1 (2C, CtBu), 31.6 (6C, CtBu), 29.1 (2C, (CH2)Cyhex), 24.8 (2C, (CH2)Cyhex), 21.4 (2C, (CH3)Mes), 21.2 (2C, (CH3)Mes), 20.8 (2C, (CH3)Mes). IR (solid): ν̃ 2851, 2862, 1618, 1542, 1447, 1309, 1264, 1211, 1035, 950, 836, 733, 550, 520. HRMS (ESI): m/z calcd for [C54H68N8O2PdAu2Cl+3 ]: 732.6364; found, 732.6339. Mp: J


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Organometallics added (5.0 mol %), the mixture was diluted with dry dichloromethane, the vial was closed and the reaction mixture was stirred for 20 h. Then the catalyst was removed via filtration over a short pad of silica using petroleum ether/ethyl acetate 4/1 as eluent. The crude mixture was purified via preparative TLC (eluent petroleum ether/ethyl acetate 9/ 1) to yield the isolated diastereomers and the enantiomeric excess for each obtained diastereomer was determined via chiral HPLC using literature known methods.10 Data for D1 (natural) are as follows. C22H24N2O5: mol wt 396.44 g mol−1. 1H NMR (CDCl3, 300 MHz, 21 °C): δ 7.68 (d, J = 8.2, 1H, CHOx), 7.35−7.30 (m, 1H, CHPh), 7.10− 7.55 (m, 4H, CHPh), 7.01 (dd, J = 7.6, J = 1.1, 1H, CHOx), 6.81−6.85 (m, 2H, CHOx), 5.03 (dd, J = 12.9, J = 4.3, 1H, CH2NO2), 4.90 (dd, J = 12.9, J = 11.0, 1H, CH2-NO2), 3.94 (dd, J = 11.0, J = 4.3, 1H, CHCH2), 1.53 (s, 9H, C(CH3)3), 1.53 (s, 3H, COx−CH3). Data for D2 (unnatural) are as follows. C22H24N2O5: mol wt 396.44 g mol−1. 1H NMR (CDCl3, 300 MHz, 21 °C): δ 7.55−7.52 (m, 1H, CHOx), 7.22− 7.05 (m, 5H, CHPh, 1 H, CHOx), 6.96−6.93 (m, 2H, CHOx), 5.13 (dd, J = 13.7, J = 10.8, 1H, CH2-NO2), 5.02 (dd, J = 13.7, J = 4.8, 1H, CH2NO2), 3.95 (dd, J = 11.0, J = 4.8, 1H, CH-CH2), 1.60 (s, 9H, C(CH3)3), 1.55 (s, 3H, COx−CH3). Analytical data are in accord with the literature.10

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Germany, 2015; pp 227−262. (i) Buchwalter, P.; Rosé, J.; Braunstein, P. Chem. Rev. 2015, 115, 28−126. (3) Selected reviews: (a) Jacobsen, E. N. Acc. Chem. Res. 2000, 33, 421−431. (b) Haak, R. M.; Wezenberg, S. J.; Kleij, A. W. Chem. Commun. 2010, 46, 2713−2723. (c) Matsunaga, S.; Shibasaki, M. Synthesis 2013, 45, 421−437. (4) Examples: (a) Hansen, K. B.; Leighton, J. L.; Jacobsen, E. N. J. Am. Chem. Soc. 1996, 118, 10924−10925. (b) Tokunaga, M.; Larrow, J. F.; Kakiuchi, F.; Jacobsen, E. N. Science 1997, 277, 936−938. (c) Nielsen, L. P. C.; Stevenson, C. P.; Blackmond, D. G.; Jacobsen, E. N. J. Am. Chem. Soc. 2004, 126, 1360−1362. (d) Sammis, G. M.; Danjo, H.; Jacobsen, E. N. J. Am. Chem. Soc. 2004, 126, 9928−9929. (e) Nielsen, L. P. C.; Zuend, S. J.; Ford, D. D.; Jacobsen, E. N. J. Org. Chem. 2012, 77, 2486−2495. (5) Selected examples: (a) Konsler, R. G.; Karl, J.; Jacobsen, E. N. J. Am. Chem. Soc. 1998, 120, 10780−10781. (b) Mazet, C.; Jacobsen, E. N. Angew. Chem., Int. Ed. 2008, 47, 1762−1765. (6) For II see: (a) DiMauro, E. F.; Kozlowski, M. C. Org. Lett. 2001, 3, 1641−1644. (b) DiMauro, E. F.; Kozlowski, M. C. Organometallics 2002, 21, 1454−1461. (c) Annamalai, V.; DiMauro, E. F.; Carroll, P. J.; Kozlowski, M. C. J. Org. Chem. 2003, 68, 1973−1981. (7) For the use of binuclear salen complexes III, see: (a) Reference 3c. (b) Handa, S.; Gnanadesikan, V.; Matsunaga, S.; Shibasaki, M. J. Am. Chem. Soc. 2007, 129, 4900−4901. (c) Handa, S.; Nagawa, K.; Sohtome, Y.; Matsunaga, S.; Shibasaki, M. Angew. Chem., Int. Ed. 2008, 47, 3230−3233. (d) Chen, Z.; Morimoto, H.; Matsunaga, S.; Shibasaki, M. J. Am. Chem. Soc. 2008, 130, 2170−2171. (e) Chen, Z.; Furutachi, M.; Kato, Y.; Matsunaga, S.; Shibasaki, M. Angew. Chem., Int. Ed. 2009, 48, 2218−2220. (f) Mouri, S.; Chen, Z.; Mitsunuma, H.; Furutachi, M.; Matsunaga, S.; Shibasaki, M. J. Am. Chem. Soc. 2010, 132, 1255− 1257. (8) Selected reviews: (a) N-Heterocyclic Carbenes in Synthesis; Nolan, S. P., Ed.; Wiley-VCH: Weinheim, Germany, 2006;. (b) N-Heterocyclic Carbenes in Transition Metal Catalysis; Glorius, F., Ed.; Springer: Berlin, 2007. (c) Diez-Gonzalez, S.; Nolan, S. P. Coord. Chem. Rev. 2007, 251, 874−883. (d) Hahn, F. E.; Jahnke, M. C. Angew. Chem., Int. Ed. 2008, 47, 3122−3172. (e) Würtz, S.; Glorius, F. Acc. Chem. Res. 2008, 41, 1523−1533. (f) Diez-Gonzalez, S.; Marion, N.; Nolan, S. P. Chem. Rev. 2009, 109, 3612−3676. (g) Dröge, T.; Glorius, F. Angew. Chem., Int. Ed. 2010, 49, 6940−6952. (9) (a) Mechler, M.; Latendorf, K.; Frey, W.; Peters, R. Organometallics 2013, 32, 112−130. (b) Mechler, M.; Frey, W.; Peters, R. Organometallics 2014, 33, 5492−5508. Studies towards the ligand precursor: (c) Kull, T.; Peters, R. Angew. Chem., Int. Ed. 2008, 47, 5461−5464. (d) Kull, T.; Cabrera, J.; Peters, R. Chem. - Eur. J. 2010, 16, 9132−9139. Related ligands: (e) Broghammer, F.; Brodbeck, D.; Junge, T.; Peters, R. Chem. Commun. 2017, 53, 1156−1159. (f) Brodbeck, D.; Broghammer, F.; Meisner, J.; Klepp, J.; Garnier, D.; Frey, W.; Kästner, J.; Peters, R. Angew. Chem., Int. Ed. 2017, 56, 4056−4060. (g) Latendorf, K.; Mechler, M.; Schamne, I.; Mack, D.; Frey, W.; Peters, R. Eur. J. Org. Chem. 2017, 4140−4167. (10) Mechler, M.; Peters, R. Angew. Chem., Int. Ed. 2015, 54, 10303− 10307. (11) Selected examples and reviews: (a) Gründemann, S.; Kovacevic, A.; Albrecht, M.; Faller, J.; Crabtree, R. H. Chem. Commun. 2001, 2274−2275. (b) Mathew, P.; Neels, A.; Albrecht, M. J. Am. Chem. Soc. 2008, 130, 13534−13535. (c) Aldeco-Perez, E.; Rosenthal, A.; Donnadieu, B.; Parameswaran, P.; Frenking, G.; Bertrand, G. Science 2009, 326, 556−559. (d) Guisado-Barrios, G.; Bouffard, J.; Donnadieu, B.; Bertrand, G. Angew. Chem., Int. Ed. 2010, 49, 4759− 4762. (e) Martin, D.; Melaimi, M.; Soleilhavoup, M.; Bertrand, G. Organometallics 2011, 30, 5304−5313. (f) Ung, G.; MendozaEspinosa, D.; Bouffard, J. Angew. Chem., Int. Ed. 2011, 50, 4215− 4218. (g) Ung, G.; Bertrand, G. Chem. - Eur. J. 2011, 17, 8269−8272. (h) Crowley, J. D.; Lee, A.; Kilpin, K. J. Aust. J. Chem. 2011, 64, 1118− 1132. (i) Donnelly, K. F.; Petronilho, A.; Albrecht, M. Chem. Commun. 2013, 49, 1145−1159. (j) Crabtree, R. H. Coord. Chem. Rev. 2013, 257, 755−766. (k) Albrecht, M. Adv. Organomet. Chem. 2014, 62,

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.7b00729. NMR and UV−vis spectra (PDF) Accession Codes

CCDC 1542512−1542513 and 1575675 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/ cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Author

*E-mail for R.P.: [email protected]. ORCID

René Peters: 0000-0002-6668-4017 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS All authors acknowledge financial support by the Deutsche Forschungsgemeinschaft (PE 818/3-1 and PE 818/7-1) allowing this project to be conducted. We also thank Mr. M.Sc. Julian Klepp for helpful discussions about complexations to Ni(II).

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REFERENCES

(1) Cooperative Catalysis − Designing Efficient Catalysts for Synthesis; Peters, R., Ed.; Wiley-VCH: Weinheim, Germany, 2015. (2) Selected reviews on bi-/polymetallic catalysis: (a) van den Beuken, E. K.; Feringa, B. L. Tetrahedron 1998, 54, 12985−13011. (b) Shibasaki, M.; Yoshikawa, N. Chem. Rev. 2002, 102, 2187−2210. (c) Shibasaki, M.; Matsunaga, S. Chem. Soc. Rev. 2006, 35, 269−279. (d) Shibasaki, M.; Kanai, M.; Matsunaga, S.; Kumagai, N. Acc. Chem. Res. 2009, 42, 1117−1127. (e) van der Vlugt, J. I. Eur. J. Inorg. Chem. 2012, 363−375. (f) Park, J.; Hong, S. Chem. Soc. Rev. 2012, 41, 6931− 6943. (g) Bratko, I.; Gómez, M. Dalton Trans. 2013, 42, 10664− 10681. (h) Weiss, M.; Peters, R. In Cooperative Catalysis − Designing Efficient Catalysts for Synthesis; Peters, R., Ed.; Wiley-VCH: Weinheim, K


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Organometallics 111−158. (l) Yuan, D.; Huynh, H. V. Organometallics 2012, 31, 405− 412. (12) Classical studies: (a) Huisgen, R. Angew. Chem., Int. Ed. Engl. 1963, 2, 565−632. (b) Michael, A. J. Prakt. Chem. 1893, 48, 94−95. (13) Cu-catalyzed azide/alkyne cycloadditions: (a) Rostovtsev, V. V.; Green, L. G.; Fokin, V. V.; Sharpless, K. B. Angew. Chem., Int. Ed. 2002, 41, 2596−2599. (b) Tornøe, C. W.; Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67, 3057−3064. (14) Ru-catalyzed azide/alkyne cycloadditions: Zhang, L.; Chen, X.; Xue, P.; Sun, H. H. Y.; Williams, I. D.; Sharpless, K. B.; Fokin, V. V.; Jia, G. J. Am. Chem. Soc. 2005, 127, 15998−15999. (15) Selected recent reviews and examples of the coordination chemistry of 1,2,3-triazoles/1,2,3-triazol-5-ylidenes: (a) Schulze, B.; Schubert, U. S. Chem. Soc. Rev. 2014, 43, 2522−2571. (b) Crowley, J. D.; McMorran, D. In Topics in Heterocyclic Chemistry; Kosmrlj, J., Ed.; Springer: Berlin/Heidelberg, 2012; Vol. 22, pp 31−83. (c) Krüger, A.; Albrecht, M. In N-Heterocyclic Carbenes: From Laboratory Curiosities to Efficient Synthetic Tools; Diez-Gonzalez, S., Ed.; RSC: Cambridge, U.K., 2010. (d) Maity, R.; van der Meer, M.; Hohloch, S.; Sarkar, B. Organometallics 2015, 34, 3090−3096. (e) Hettmanczyk, L.; Manck, S.; Hoyer, C.; Hohloch, S.; Sarkar, B. Chem. Commun. 2015, 51, 10949−10952. (f) Maity, R.; van der Meer, M.; Sarkar, B. Dalton Trans. 2015, 44, 46−49. (g) Petronilho, A.; Woods, J. A.; Bernhard, S.; Albrecht, M. Eur. J. Inorg. Chem. 2014, 708−714. (h) Maity, R.; Hohloch, S.; Su, C.-Y.; van der Meer, M.; Sarkar, B. Chem. - Eur. J. 2014, 20, 9952−9961. (i) Hohloch, S.; Hettmanczyk, L.; Sarkar, B. Eur. J. Inorg. Chem. 2014, 3164−3171. (j) Hohloch, S.; Frey, W.; Su, C.-Y.; Sarkar, B. Dalton Trans. 2013, 42, 11355−11358. (k) Aizpurua, J. M.; Sagartzazu-Aizpurua, M.; Monasterio, Z.; Azcune, I.; Mendicute, C.; Miranda, J. I.; Garcia-Lecina, C.; Altube, A.; Fratila, R. M. Org. Lett. 2012, 14, 1866−1868. (l) Keske, L.; Zenkina, O. V.; Wang, R.; Crudden, C. M. Organometallics 2012, 31, 456−461. (m) Zamora, M. T.; Ferguson, M. J.; Cowie, M. Organometallics 2012, 31, 5384−5395. (n) Cai, J.; Yang, X.; Arumugam, K.; Bielawski, C. W.; Sessler, J. L. Organometallics 2011, 30, 5033−5037. (o) Kilpin, K. J.; Paul, U. S. D.; Lee, A.-L.; Crowley, J. D. Chem. Commun. 2011, 47, 328−330. (16) Selected examples for catalytic applications: (a) Lalrempuia, R.; Müller-Bunz, H.; Bernhard, S.; Albrecht, M. Angew. Chem., Int. Ed. 2010, 49, 9765−9768. (b) Krüger, A.; Albrecht, M. Aust. J. Chem. 2011, 64, 1113−1117. (c) Krüger, A.; Häller, L. J. L.; Müller-Bunz, H.; Serada, O.; Neels, A.; Macgregor, S. A.; Albrecht, M. Dalton Trans. 2011, 40, 9911−9920. (d) Saravanakumar, R.; Ramkumar, V.; Sankararaman, S. Organometallics 2011, 30, 1689−1694. (e) Nakamura, T.; Terashima, T.; Ogata, K.; Fukuzawa, S. Org. Lett. 2011, 13, 620− 623. (f) Huang, J.; Hong, J.-T.; Hong, S. H. Eur. J. Org. Chem. 2012, 6630−6635. (g) Wright, J. R.; Young, P. C.; Lucas, N. T.; Lee, A.-L.; Crowley, J. D. Organometallics 2013, 32, 7065−7076. (h) Bolje, A.; Kosmrlj. Org. Lett. 2013, 15, 5084−5087. (i) Reference 15j. (j) Hohloch, S.; Scheiffele, D.; Sarkar, B. Eur. J. Inorg. Chem. 2013, 3956−3965. (k) Hohloch, S.; Suntrup, L.; Sarkar, B. Organometallics 2013, 32, 7376−7385. (l) Bolje, A.; Hohloch, S.; Urankar, D.; Pevec, A.; Gazvoda, M.; Sarkar, B.; Košmrlj, J. Organometallics 2014, 33, 2588−2598. (m) Hohloch, S.; Kaiser, S.; Duecker, F. L.; Bolje, A.; Maity, R.; Košmrlj, J.; Sarkar, B. Dalton Trans. 2015, 44, 686−693. (17) (a) Braunstein, P.; Naud, F. Angew. Chem., Int. Ed. 2001, 40, 680. (b) Zhang, W.-H.; Chien, S. W.; Hor, T. S. A. Coord. Chem. Rev. 2011, 255, 1991−2024. (18) (a) Formylation: Bhatt, S.; Nayak, S. K. Tetrahedron Lett. 2009, 50, 5823−5826. (b) Bromomethylation: Wang, Q.; Wilson, C.; Blake, A. J.; Collinson, S. R.; Tasker, P. A.; Schröder, M. Tetrahedron Lett. 2006, 47, 8983−8997. (19) Pathak, R. K.; Dikundwar, A. G.; Row, T. N. G.; Rao, C. P. Chem. Commun. 2010, 46, 4345−4347. (20) Supplementary crystallographic data for 5-Mes have been deposited with the Cambridge Crystallographic Data Centre as deposition number1542512. This material is available free of charge via the Internet at http://pubs.acs.org and http://www.ccdc.cam.ac. uk/products/csd/request/.

(21) Selected references: (a) Hettmanczyk, L.; Schulze, D.; Suntrup, L.; Sarkar, B. Organometallics 2016, 35, 3828−3836. (b) Reference 15b. (c) Saravanakumar, R.; Ramkumar, V.; Sankararaman, S. J. Organomet. Chem. 2013, 736, 36−41. (d) Schaper, L.-A.; Wei, X.; Hock, S. J.; Pöthig, A.; Ö fele, K.; Cokoja, M.; Herrmann, W. A.; Kühn, F. E. Organometallics 2013, 32, 3376−3384. (e) Terashima, T.; Inomata, S; Ogata, K.; Fukuzawa, S. Eur. J. Inorg. Chem. 2012, 1387− 1393. (f) Schulze, B.; Escudero, D.; Friebe, C.; Siebert, R.; Görls, H.; Köhn, U.; Altuntas, E.; Baumgaertel, A.; Hager, M. D.; Winter, A.; Dietzek, B.; Popp, J.; González, L.; Schubert, U. S. Chem. - Eur. J. 2011, 17, 5494−5498. (22) (a) de Frémont, P.; Scott, N. M.; Stevens, E. D.; Ramnial, T.; Lightbody, O. C.; Macdonald, C. L. B.; Clyburne, J. A. C.; Abernethy, C. D.; Nolan, S. P. Organometallics 2005, 24, 6301−6309. (b) See refs 9a and 9b. For a review containing an excellent compilation of possible structures: Garrison, J. C.; Youngs, W. Chem. Rev. 2005, 105, 3978− 4008. (23) Canseco-Gonzalez, D.; Petronilho, A.; Mueller-Bunz, H.; Ohmatsu, K.; Ooi, T.; Albrecht, M. J. Am. Chem. Soc. 2013, 135, 13193−13203. (24) For mixtures of Au(I) carbene species, see e.g.: (a) Guo, S.; Bernhammer, J. C.; Huynh, H. V. Dalton Trans. 2015, 44, 15157− 15165. (b) Sivaram, H.; Jothibasu, R.; Huynh, H. V. Organometallics 2012, 31, 1195−1203. (25) See for example: (a) Ung, G.; Soleilhavoup, M.; Bertrand, G. Angew. Chem., Int. Ed. 2013, 52, 758−761. (b) Mendoza-Espinosa, D.; Rendón-Nava, D.; Alvarez-Hernández, A.; Angeles-Beltrán, D.; Negrón-Silva, G. E.; Suárez-Castillo, O. R. Chem. - Asian J. 2017, 12, 203−207. (c) ref 24b. (26) Hofer, M.; Nevado, C. The formation of Au(III) complexes by oxidation of Au(I)-aryl complexes with PhICl2 has recently been used in catalysis. Tetrahedron 2013, 69, 5751−5757. (27) Supplementary crystallographic data for 12-Ni have been deposited with the Cambridge Crystallographic Data Centre as deposition number 1575675. This material is available free of charge via the Internet at http://pubs.acs.org and http://www.ccdc.cam.ac. uk/products/csd/request/. (28) Bondi, A. J. Phys. Chem. 1964, 68, 441−451. (29) See e.g.: Ayerbe Garcia, M.; Frey, W.; Ringenberg, M.; Schwilk, M.; Peters, R. Chem. Commun. 2015, 51, 16806−16809. (30) Poulain, A.; Canseco-Gonzalez, D.; Hynes-Roche, R.; MüllerBunz, H.; Schuster, O.; Stoeckli-Evans, H.; Neels, A.; Albrecht, M. Organometallics 2011, 30, 1021−1029. (31) Supplementary crystallographic data for 14-Pd have been deposited with the Cambridge Crystallographic Data Centre as deposition number 1542513. This material is available free of charge via the Internet at http://pubs.acs.org and http://www.ccdc.cam.ac. uk/products/csd/request/. (32) Selected examples of heterodinuclear Pd(II) or Ni(II) complexes: (a) Andrieu, J.; Braunstein, P.; Drillon, M.; Dusausoy, Y.; Ingold, F.; Rabu, P.; Tiripicchio, A.; Ugozzoli, F. Inorg. Chem. 1996, 35, 5986−5994. (b) Liu, S.; Peloso, R.; Braunstein, P. Dalton Trans. 2010, 39, 2563−2572. (c) Zhang, S.; Pattacini, R.; Braunstein, P. Dalton Trans. 2011, 40, 5711−5719. (33) Selected examples are as follows. MnIII catalysts: (a) Kato, Y.; Furutachi, M.; Chen, Z.; Mitsunuma, H.; Matsunaga, S.; Shibasaki, M. J. Am. Chem. Soc. 2009, 131, 9168−9169 Ni diamine catalysts:. (b) Han, Y.-Y.; Wu, Z.-J.; Chen, W.-B.; Du, X.-L.; Zhang, X.-M.; Yuan, W.-C. Org. Lett. 2011, 13, 5064−5067. Organocatalysts: (c) Bui, T.; Syed, S.; Barbas, C. F., III J. Am. Chem. Soc. 2009, 131, 8758−8759. (d) Li, X.; Zhang, B.; Xi, Z.-G.; Luo, S.; Cheng, J.-P. Adv. Synth. Catal. 2010, 352, 416−424. (e) Zou, L.; Bao, X.; Ma, Y.; Song, Y.; Qu, J.; Wang, B. Chem. Commun. 2014, 50, 5760−5762. Phase-transfer catalysts: (f) He, R.; Shirakawa, S.; Maruoka, K. J. Am. Chem. Soc. 2009, 131, 16620−16621. Polyfunctional catalysts: (g) Reference 10. (34) Podgoršek, A.; Iskra, J. Molecules 2010, 15, 2857−2871.

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