Different Coordination Modes of the Ph2PCsp3PPh2 Pincer Ligand in

Jul 8, 2015 - Different Coordination Modes of the Ph2PCsp3PPh2 Pincer Ligand in ... with equimolar amounts of PCP gave the dimeric rhodium complex 1...
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Different Coordination Modes of the Ph2PCsp3PPh2 Pincer Ligand in Rhodium Complexes as a Consequence of Csp3−H Metal Interaction Janet Arras, Hansjörg Speth, Hermann A. Mayer,* and Lars Wesemann* Institut für Anorganische Chemie, Universität Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany S Supporting Information *

ABSTRACT: Starting from commercially available 4,4′-di-tertbutyldiphenylmethane the pincer ligand bis(4-tert-butyl-2(diphenylphosphino)phenyl)methane (PCP) was prepared in two steps in moderate yield. Treatment of a solution of RhCl3· 3H2O in a mixture of isopropyl alcohol and toluene with equimolar amounts of PCP gave the dimeric rhodium complex 1. In an electrophilic metalation a facially coordinated pincer complex is formed. When PCP is treated with [CODRhCl]2 in a solution of pyridine, the square-pyramidal complex 2 is generated where the bis-phosphine PCP acts as bidentate ligand that coordinates in a cis fashion. SnCl2 inserts into the Rh−Cl bond of 2, which results in an oxidative addition of one of the methylene C−H bonds to form the Rh(III) complex 3, where the PCP ligand coordinates in a meridional way. A 2 equiv portion of PCP reacts with 1 equiv of [CODRhCl]2 in the presence of the electron-donating ligands HPhPC6H4NMe2, PPh2Py, and PPh3, respectively, as well as with stanna- and germa-closododecaborate to give the octahedral Rh(III) complexes 4−8. Attempts to remove the HCl with KOtBu from complexes 4−6 produces the planar Rh(I) compounds 9 and 10. No carbene formation has been observed.

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INTRODUCTION Interest in meridionally coordinating tridentate pincer ligand systems has been growing continuously over the past several years. These systems stabilize metal complexes over a broad temperature range while maintaining remarkable reactivities. Thus, the chemistry of pincer complexes has developed into an attractive field for studying different types of bond activations, synthesis, and catalysis1,2 as well as for mechanistic investigations.3−5 Although the diversity of pincer ligand systems with different donor variations has increased dramatically, PCP systems have remained the focus of interest.6,7 Recent developments have concentrated on central carbene−metal interactions and ipso-Csp3−H metal bonds, as both exert a strong translabilizing effect.8−20 Thus, the higher electron donating ability of the ipso-Csp3−H metal bond in comparison to the Csp2 metal bond results in higher reactivity.21,22 This has been nicely demonstrated in the case of N−H activation of ammonia.23 While the [tBu2P(CH2)2]2CHIr fragment oxidatively adds a N− H bond to form a hydride amide complex, the less electron rich C6H3-1,5-(tBu2P)2Ir fragment readily coordinates ammonia. Furthermore, other interesting aspects of the ipso-Csp3−H metal bond has been outlined recently.24 The synthesis of pincer complexes is of topical interest. In particular for PCP ligand systems the key process of the carbon− metal bond formation has been subject of discussion since the discovery of the pincer ligand complexes.25 It is accepted that PCP ligands precoordinate to the metal center via the two phosphine donors.26−35 This arranges the CH2 group close to the metal center and facilitates the interaction of the C−H bonds with the metal complex fragment.29 Depending on the electronic properties of the phosphine, the ligand backbone, and the nature © XXXX American Chemical Society

of the metal complex fragment the C−H metal interaction can cover the whole range from no interaction at all via weak, agostic, and strong interactions until the C−H bond breaks, which finally leads to a metalation of the C−H bond. Moreover, the metalated C−H bond can initiate carbene formation. Examples of each situation have been reported in the literature.11,27,29,35−41 More interestingly, as in some cases the C−H unit is able to reversibly change the structure in the ligand backbone, it can be used to control the coordination mode and coordination properties, which makes these systems applicable for ligand metal cooperation in certain reactions.21 Unfortunately the purely aliphatic pincer ligand backbone is highly dynamic27,36 and provides α- and β-hydrogens that can be easily abstracted, which leads to isomerization (Scheme 1).42 To reduce the ligand dynamics and improve the communication of the C−H bonds with the metal center, the CH2 group has been incorporated into cyclic systems8,11,43,44 or ridged linkers such as pyrrole and phenyl rings have been placed between the Scheme 1

Received: May 22, 2015

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DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX

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Organometallics Scheme 2. a

a

P = PPh2. L = HP(Ph)o-C6H4NMe2 (4), PPh2Py (5, 9), PPh3 (6, 10). E = SnB11H112− (7), GeB11H112− (8).

phenyl)methane (PCP) is accessible in two steps in moderate yield (Scheme 2). Details are outlined in the Experimental Section.52 All NMR spectra agree with a Cs/C2 symmetry of the compound, as displayed in Scheme 2. The most salient features are a singlet in the 31P{1H} NMR spectrum at δ −13.1 and a triplet in both the 1H NMR (4.84 ppm, 4JP,H = 2.2 Hz) and 13 C{1H} NMR (37.8 ppm, 3JP,C = 22.4 Hz) spectra of the methylene group which connects the two (diphenylphosphino)phenyl units. Overall, all chemical shifts of the respective resonances of the PCP ligand are very similar to the corresponding shifts of (bis-2-(diphenylphosphino)phenyl)methane.29 After treatment of a solution of RhCl3·3H2O in a mixture of isopropyl alcohol and toluene with an equimolar amount of PCP the dimeric rhodium complex 1 could be isolated (Scheme 2). An electrophilic53 metalation of a methylene C−H bond was successfully achieved. Compound 1 represents a rare case of a facial coordination of a PCP pincer ligand to a metal center48 and compares well with the monomeric complex (bis(2diphenylphosphinophenyl)methyl)RhCl2MeCN.29 Obviously in the absence of a stronger coordinating solvent the (4-tBu-2Ph2P-C6H3)2CH)RhCl2 dimerizes to 1 to complete the coordination sphere of rhodium. The situation changes when PCP is treated with [(COD)RhCl]2 in a solution of pyridine. In a room-temperature reaction the orange square-pyramidal complex 2 forms after 30 min in high yield (87.8%). Here the bisphosphine PCP acts as a bidentate ligand that coordinates in a cis fashion to the metal center while one chlorine and two pyridines

phosphine donors and the central methylene group (Scheme 1).7,14,29,45 Still, the Csp3−H bond cleavage remains challenging. Further aspects are the donation ability and the steric demand of the phosphine donors of the PCP ligands. Thus, bulky tertiary phosphines such as tBu2P and iPr2P hinder the mutual cis coordination while the less sterically demanding Ph2P phosphine coordinates either mutually cis or trans to metal complex fragments.25 Consequently the sterically ambitious and strongly donating RPCP ligands with R = tBu, iPr are the most applied pincer ligand systems, as they support the meridional coordination with strong metal carbon bonds.3,46,47 Less sterically demanding and less electron donating RPCP (R = Ph, CF3) ligands lead to nonmeridional coordination geometries.29,48−50 Here we report on the preparation of bis(4-tert-butyl-2(diphenylphosphino)phenyl)methane (PCP) and demonstrate that the coordination chemistry strongly depends on the electronic nature of the rhodium complex precursor and further participating ligands.

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RESULTS AND DISCUSSSION Interestingly, the first time the pincer ligand (bis-2(diphenylphosphino)phenyl)methane was reported, it was generated in the coordination sphere of a ruthenium complex by serendipity.51 Later, a rather complex reaction scheme was developed to prepare (bis-2-(diphenylphosphino)phenyl)methane in six steps.29 On the other hand, starting from commercially available 4,4′-di-tert-butyldiphenylmethane the new pincer ligand (bis(4-tert-butyl-2-(diphenylphosphino)B

DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX

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Organometallics make up the coordination sphere of the Rh(I) complex 2. No C− H metalation of one of the methylene C−H bonds with the rhodium center is observed. In a toluene solution of 2 SnCl2 inserts into the Rh−Cl bond, which converts the weak-transinfluence ligand Cl− into the strong-trans-influence SnCl3− ligand. This changes the electronic situation at the rhodium that in the following one pyridine ligand is lost and the resulting low-coordinated Rh(I) complex fragment oxidatively adds one of the methylene C−H bonds. Interestingly in the isolated pale yellow Rh(III) complex 3 the PCP ligand occupies meridional positions while SnCl3− coordinates trans to the Csp3−H bond. The compositions of compounds 1−3 have been verified by their elemental analyses, while structural details can be deduced from their NMR spectra in solution and from X-ray analyses in the solid state. Thus, a large coordination chemical shift is observed for the singlets in the 31P{1H} NMR spectra of 1 (Δδ = 68.4) and 3 (Δδ = 66.1), respectively. This is typical for compounds where the phosphorus is incorporated into a fivemembered ring,54 which is a consequence of the C−H metalation in 1 and 3. In contrast to this, for larger metallacycles as in 2 Δδ is less pronounced (44.8 and 56.3). The two doublets detected in the 31P{1H} NMR spectrum of 2 are consistent with a C1 symmetry, while the small phosphorus−phosphorus interaction (2JP,P = 43 Hz) agrees with a cis arrangement of the ligand. Due to the C1 symmetry the two methylene protons in 2 become diastereotopic, while their close proximity to the metal is indicated by a large chemical shift difference between the two protons. Thus, the 1H NMR spectrum of 2 shows a doublet for the exo proton (3.49 ppm) and a doublet of triplets for the endo proton (7.77 ppm). The geminal coupling (2JH,H = 13.8 Hz) and the phosphorus coupling (4JP,H = 2.8) are compatible with those reported for comparable palladium and platinum complexes.29 The downfield shift of the endo proton is characteristic of a weak long-range interaction of the endo proton with the metal.29,35,40,55 After metalation of the endo C−H bonds in 1 and 3 the remaining exo protons are shifted downfield to 8.78 ppm (1) and 5.74 ppm (d, 2JRh,H = 4.0 Hz, 3JSn,H = 67.2 Hz) (3), respectively. The doublet of triplets observed for the hydride resonance in the 1H NMR spectrum of 3 at −17.46 ppm supports the meridional coordination of PCP in 3. Moreover, the small 2 JP,H and 2JSn,H interactions and the chemical shift agree with a hydride coordinated cis to the phosphines and tin and trans to a ligand with a weak trans influence.56 The metalated carbons appear as doublets at δ 55.9 ppm (1JRh,C = 21.5 Hz) in 1 and 58.4 ppm (1JRh,C = 25.4 Hz) in 3 in the 13 C{1H} NMR spectra. Interestingly while the two CH2 protons show a marked effect upon coordination of PCP to the rhodium in 2, the 13C chemical shifts of the CH2 groups in PCP and 2 hardly differ (38.0 ppm (2) vs 37.8 ppm in PCP). Suitable crystals of the rhodium dichloride complex 1 were obtained by slow diffusion of hexane into a toluene solution of 1. The dimer 1 crystallizes together with three molecules of toluene in the triclinic space group P1̅ with the dimeric pincer complex lying on a center of symmetry. The molecular structure is depicted in Figure 1 together with selected interatomic distances and angles. The rhodium complex shows a slightly distorted octahedral geometry with the PCP pincer ligand coordinated in a facial arrangement. The interatomic distances and angles can be compared with the values found in the monomeric acetonitrile adduct [Rh((2-Ph2P-C6H3)2CH)Cl2(NCCH3)].29 Because of the sp3 character of the carbon atom C1 and the steric requirements of the phenyl substituents the angles P1−Rh−P2 and C3−C1−C2 are expanded to 100.7(1) and 111.9(2)°,

Figure 1. Molecular structure (ORTEP diagram, shown with 50% displacement ellipsoids) of complex 1 in the solid state. Hydrogen atoms have been omitted for clarity. Selected bond lengths (Å) and angles (deg): Rh1−C1 2.095(3), Rh1−P1 2.2279(7), Rh1−P2 2.2465(7), Rh1−Cl1 2.4893(6), Rh1−Cl2 2.4222(6), Rh1−Cl2′ 2.4570(6); P1− Rh1−P2 100.7(1), C1−Rh1−P1 86.0(1), C1−Rh1−P2 86.2(1), C3− C1−C2 111.9(2), Rh1−Cl2−Rh1′ 98.0(1).

respectively. Due to the high trans influence of the carbon ligand in complex 1 the Rh−Cl1 bond in a position trans to the carbon ligand is slightly longer than the Rh−Cl2 bond. The molecular structure of the pyridine adduct 3 crystallized from benzene solution is presented in Figure 2 together with

Figure 2. Molecular structure (ORTEP diagram̧ shown with 50% displacement ellipsoids) of complex 3 in the solid state. Selected bond lengths (Å) and angles (deg): Rh−Sn 2.55873(6), Rh−C1 2.162(5), Rh−N1 2.221(5), Rh−P1 2.282(1), Rh−P2 2.296(1), Sn−Cl1 2.417(2), Sn−Cl2 2.402(2), Sn−Cl3 2.399(2); P1−Rh−P2 165.0(2), Sn−Rh−C1 165.9(2), C3−C1−C2 117.1(5).

selected interatomic distances and angles. The PCP pincer ligand shows a meridional coordination mode, and the Rh−P interatomic distances are slightly longer than the bond lengths in the facially coordinated derivative 1. The Rh−C distance is also longer than the Rh−C bond found in complex 1, which can be explained by the stronger trans influence of the trichlorostannate in comparison to the chloride ligand.57 The Rh−Sn bond length of 2.55873(6) Å lies in the range of Rh−SnCl3 derivatives reported earlier.58−60 Coordination of the pyridine ligand at Rh(III) in complex 3 exhibits a typical Rh−N bond C

DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX

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Organometallics length of 2.221(5) Å, indicating trans coordination to a ligand with a strong trans influence.61,62 The hydride ligand was placed in a calculated position and refined with a fixed geometry. In summary, treatment of PCP with electron-poor RhIIICl3 leads to an electrophilic C−H activation and a facial coordination of the PCP pincer ligand. In complex 2 the ligand PCP acts as a bis-phosphine which occupies two cis positions of a squarepyramidal complex. Only when a strongly electron donating ligand is present in the coordination sphere a methylene C−H bond is oxidatively added to the rhodium and a meridional coordination of the PCP ligand is achieved. To further support these findings, 2 equiv of PCP were treated with 1 equiv of [CODRhCl]2 in the presence of the electrondonating ligands HPhPC6H4NMe2, PPh2Py and PPh3, respectively, as well as with stanna- and germa-closo-dodecaborate. This allowed the isolation of complexes 4−8 in good yield (Scheme 2). As in 3, in each case one of the methylene C−H bonds oxidatively adds to the rhodium center, forming merdionally coordinated PCP pincer complexes. In all compounds the electron-donating ligands arrange trans to the metalated carbon. The abstraction of HCl with KOtBu from complexes 5,6 produces the planar compounds 9,10. No metal−carbene bond formation was observed even when an excess of base was applied. The coordination of the electron-donating ligands L and E increase the number of NMR-active nuclei in the coordination spheres of the rhodium complexes 4−10. This causes a further splitting of the multiplet patterns in the corresponding NMR spectra of 4−6 and 8−10 or in additional satellite spectra in 7. Analyses of the multiplets support the structures of the molecules as displayed in Scheme 2. Thus, the 31P{1H} NMR spectra of 5, 6 and 9, 10 are characterized by doublets of doublets and doublets of triplets due to mutual coupling of the phosphorus nuclei and further splitting by rhodium. Interestingly, upon coordination of HPhPC6H4NMe2 to rhodium chirality is introduced into complex 4, which generates diastereotopic trans phosphines. Consequently, in the 31P{1H} NMR spectrum of complexes 4 three distinct resonances were detected with small and large 2JP,P coupling constants (26 and 386 Hz in 4) typical for cis and trans P−Rh−P arrangements.63 Overall the chemical shifts of the phosphorus nuclei and the 1JRh,P as well as the 2JP,P interactions in compounds 4−10 reflect the different bond characteristics of the respective trans-coordinated ligands and the rhodium oxidation state.64,65 The 13C chemical shifts of the metalated carbon atoms in complexes 4−10 cover the range between 51.9 and 57.2 ppm. The resonances are split into doublets of doublets by the interaction with rhodium and the phosphine located trans to the carbon nuclei. The sizes of the 1JRh,C coupling constants (19−24 Hz) agree with those observed for typical C−Rh σ bonds. The 1H NMR spectra of complexes 4−8 exhibit hydride signals in the range of −17.54 to −15.92 ppm. Due to coupling to rhodium and to the phosphorus nuclei a ddt (5 and 6), a dddd (4), and a dt (7 and 8) were detected. The extraction of the coupling constants was supported by different decoupling experiments and simulation of the multiplet patterns (Figures 3 and 4). The chemical shifts of the remaining exo C−H protons of the bridging methylene unit can only be assigned with the support of 1H−13C HSQC NMR experiments. In the 1H NMR spectra of the metal complexes 4−6, 9, and 10 these resonances were detected in the aromatic region between 7.2 and 7.6 ppm. In the case of 7 and 8 the bridging methylene C−H protons exhibit distinct doublets at 5.8 and 5.7 ppm (2JRh,H = 4.1 in 7 and 3.2 Hz in 8), respectively. Additionally for compound 7 the 3JSn,H

Figure 3. 1H NMR spectra of complex 4: (a) hydride region; (b) 1 H{31P(@ −18.3}; (c) 1H{31P(@ 37.7)}; (d) 1H{31P(@ 50.4}.

Figure 4. (a) Hydride region of 1H NMR spectra of complex 4: (a) simulated spectrum with parameters 2JP,H = 16.0 Hz, 2JP,H = 11.5 Hz, and 2 JP,H = 11.5 Hz (1JRh,H = 22.4 Hz was obtained from (f)); (b) experimental spectrum; c) experimental 1H{31P(@ 37.7 and 31P(@ 50.4} spectrum; (d) simulated 1H{103Rh} spectrum with the parameters 2 JP,H = 16.0 Hz, 2JP,H = 11.5 Hz, and 2JP,H = 11.5 Hz; (e) 1H{103Rh} spectrum; (f) 1H{31P} spectrum.

coupling leads to tin satellites (3J117Sn,H = 53.9 Hz, 3J119Sn,H = 61.4 Hz). Complex 5 crystallizes in the orthorhombic space group Pna21. The molecular structure of the rhodium complex exhibiting octahedral coordination at the rhodium atom is shown in Figure 5, along with interatomic distances and angles. The Rh−P interatomic distances of the meridionally coordinated pincer ligand are slightly longer than the values found in complex 3. The Rh−C bond length of 2.145(2) Å is shorter than the comparable value found in the trichlorostannate derivate 3 (2.162(5) Å) and reflects the weaker trans influence of the phosphine ligand in comparison to the SnCl3 ligand. The monodentate phosphine ligand exhibits the largest Rh−P3 distance of 2.3592(6) Å in complex 5, which is the result of the trans influence of the carbon ligand. The trichlorostannate complex 3 and the stanna-closododecaborate coordination compound 7 show similar geometries (Figure 6). The pincer ligand is coordinated in a meridional arrangement, and the tin ligand is in a position trans to the carbon ligand of the pincer moiety. The Rh−Sn distance is comparable with those of other stanna-closo-dodecaborate complexes of rhodium.66

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CONCLUSION In spite of the incorporation of rigid phenyl rings into the ligand backbone, the PCP ligand remains highly flexible. This has been D

DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX

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Organometallics

Complexes 1 and 2 represent rare cases where the phosphine donors of potential PCP pincer ligands coordinate cis to each other. Obviously there are no steric constraints that are responsible for the phosphine donors arranging in mutually trans positions in complexes 3−10 (Scheme 2 and Figures 2, 3, 5, and 6). Moreover, the common feature of complexes 3−10 are additional electron-donating ligands which increase the electron density at the metal center, facilitating the oxidative addition of one of the methylene C−H bonds. This is compatible with recently reported iron complexes.15 Obviously if the phosphines are provided with alkyl groups as in (2-R2PC6H4)2CH2 (R = iPr, t Bu) the electron-donating ability of the corresponding pincer ligand is sufficient enough to support the oxidative addition of one of the methylene C−H bonds to iridium(I) fragments without additional electron-donating ligands.13,16 The coordination mode of the PCP ligand to rhodium obviously depends on the balance of electronic effects which are contributed by the PCP ligand itself, other participating ligands, and the metal center.

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Figure 5. Molecular structure (ORTEP diagram̧ shown with 50% displacement ellipsoids) of complex 5 in the solid state. Selected bond lengths (Å) and angles (deg): Rh−P1 2.3139(7), Rh−P2 2.2955(7), Rh−P3 2.3592(6), Rh−C1 2.145(2), Rh−Cl 2.5057(5); P1−Rh−P2 151.93(2), C1−Rh−P3 178.25(7), C1−Rh−Cl 87.56(7), C2−C1−C3 115.9(2), P2−Rh−Cl 97.92(2), P1−Rh−Cl 104.06(2), P3−Rh−Cl 90.70(2).

EXPERIMENTAL SECTION

General Considerations. All reactions were performed under an argon atmosphere in an MBraun glovebox or by using standard Schlenk techniques. 4,4′-Di-tert-butyldiphenylmethane was purchased from ABCR and used without further purification. HPhPC6H4NMe267 and 2,2′-diiodo-4,4′-di(tert-butyl)diphenylmethane52 were synthesized according to published procedures. Solvents were purified by established methods and stored under argon. [D6]Benzene and [D3]acetonitrile were degassed by three freeze−pump−thaw cycles. Unless otherwise stated, 1H, 13C, and 31P NMR characterization data were obtained at 299 K by using a Bruker AVII+400 NMR spectrometer (equipped with a 5 mm QNP probe head and operating at 400.13, 100.6, and 162.0 MHz, respectively). 11B and 119Sn NMR data were obtained at 299 K using a Bruker DRX-250 NMR spectrometer (equipped with a 5 mm ATM probe head and operating at 80.3 and 93.2 MHz, respectively). 31 1 103 P{ H, Rh}−103Rh HMQC NMR data were collected on a Bruker DRX-250 NMR spectrometer (equipped with a 5 mm low-γ probe head and operating at 101.3 (31P) and 8.0 MHz (103Rh)). 1H−31P HMBC NMR data were collected on a Bruker Avance II+ 500 NMR spectrometer (equipped with a 5 mm ATM probe head and operating at 500.13 (1H) and 202.5 (31P) MHz). 1H{31P} and 1H{103Rh} NMR data were collected on a Bruker Avance II+ 500 NMR spectrometer (equipped with a 5 mm low-γ probe head and operating at 500.13 (1H) and 15.8 MHz (103Rh)). Chemical shifts (δ) are reported in parts per million relative to external SiMe4 (for 1H and 13C), 85% H3PO4 in D2O (for 31P), BF3·Et2O (for 11B), and SnMe4 (for 119Sn) by using the chemical shift of the solvent 2H resonance frequency in combination with the unified frequency scale according to paragraph 3.6 of the IUPAC 2001 recommendations. 1H and 13C NMR chemical shift assignments were supported by 1H−1H COSY, 1H−13C HSQC, and 1 H−13C HMBC NMR experiments. Elemental analyses were performed with a Vario MICRO EL analyzer from Elementar Co. Crystallography. X-ray data were collected with a Bruker APEX-II CCD diffractometer equipped with a sealed-tube source with molybdenum anode and graphite monochromator (compounds 1, 3− 5, 7, and 8). For data reduction and absorption correction Bruker’s APEX2, including the programs SAINT, SADABS, and XPREP, was used.68,69 The structure was solved and refined by using the SHELXTL software package and the WinGX program suite.70−73 Syntheses. Bis(4-tert-butyl-2-(diphenylphosphino)phenyl)methane (PCP). 2,2′-Diiodo-4,4′-di(tert-butyl)diphenylmethane (1.15 g, 2.16 mmol) dissolved in 20 mL of pentane was treated with a hexane solution of n-butyllithium (2.7 mL, 4.32 mmol, 1.6 M). After the mixture was stirred at room temperature for 3 h, the precipitate was separated, washed with pentane (three times), and suspended in toluene at 0 °C. A hexane solution of chlorodiphenylphosphine (0.79 mL, 4.32 mmol) was added dropwise at 0 °C. The resulting solution was stirred at room

Figure 6. Molecular structure (ORTEP diagram̧ shown with 50% displacement ellipsoids) of complex 7 in the solid state. Selected bond lengths (Å) and angles (deg): Rh−P1 2.2846(6) [2.2758(6)], Rh−P2 2.2720(6) [2.2750(6)], Rh−C1 2.142(2) [2.144(2)], Rh−Sn 2.6026(2) [2.6058(2)], Rh−N 2.1271(18) [2.134(2)]; P1−Rh−P2 161.8(1) [161.4(1)], C1−Rh−Sn 177.4(1) [176.34(6)], C1−Rh−N 89.3(1) [176.3(1)], C2−C1−C3 116.0(2) [115.5(2)], P1−Rh−N 96.6(1) [92.5(1)], P2−Rh−N 93.4(1) [99.10(6)], Sn−Rh−N 92.0(1) [92.7(1)].

demonstrated by the isolation of rhodium complexes with the PCP ligand in different coordination modes. Thus, in 1 it was found that PCP behaves as a tridentate ligand that coordinates facially in an octahedral rhodium(III) complex (Scheme 2, Figure 1). In contrast to this, PCP acts as a simple bidentate chelate in the square-pyramidal complex 2 (Scheme 2). E

DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX

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Organometallics temperature for 2 days. The volatile components of the solution were removed in vacuo. Recrystallization from methanol afforded PCP (0.35 g, 24.8% yield) as a white solid. 1H NMR (400.11 MHz, C6D6): δ 1.10 [s, 18H, (CCH3)], 4.84 [t, 4JP,H = 2.2 Hz, 2H, CH2], 7.00−7.08 [m, 12H, Ph], 7.08−7.11 [m, 4H, C6H3], 7.25 [m, 2H, C6H3], 7.41 [m, 8H, Ph]. 13 C{1H} NMR (100.6 MHz, C6D6): δ 30.9 [s, (CCH3)], 34.2 [s, (CCH3)], 37.8 [t, 3JP,C = 22.4 Hz, CH2], 125.8 [s, C6H3], 128.3 [m, Ph], 130.1 [m, C6H3], 130.8 [s, C6H3], 134.0 [m, Ph], 136.0 [m, C6H3], 137.6 [m, Ph], 142.9 [m, C6H3], 148.5 [s, C6H3]. 31P{1H} NMR (101.3 MHz, C6D6): δ −13.3 [s]. Anal. Calcd for C45H46P2 (PCP): C, 83.31; H, 7.15. Found: C, 82.87; H, 7.12. [(4-tBu-2-Ph2P-C6H3)2CH)RhCl2]2 (1). A solution of RhCl3·3H2O (19.9 mg, 0.076 mmol) in 10 mL isopropyl alcohol/water (9/1) was stirred for 30 min. Afterward a solution of PCP (50.0 mg, 0.076 mmol) in 5 mL of toluene was added. After the mixture was stirred for 2 h at 90 °C, all volatiles were removed in vacuo to isolate 1 as a yellow solid (56.5 mg; 91.1% yield). Slow diffusion of hexane into a solution of 3 in toluene gave yellow crystals. 1H NMR (250.13 MHz, C6D6): δ 1.03 [s, 36H, C(CH3)3], 6.32 [m, 8H, Ph], 6.56 [m, 4H, Ph], 6.96 [m, 12H, Ph], 7.24 [m, 8H, C6H3], 7.40 [m, 8H, Ph], 8.23 [m, 8H, Ph], 8.37 [m, 4H, C6H3], 8.78 [s, 2H, CCHC]. 13C {1H} NMR (100.6 MHz, C6D6): δ 30.9 [C(CH3)3], 33.9 [C(CH3)3], 55.9 [d, 1JRh,C = 21.5 Hz, CCHC], 127.1 [m, Ph], 127.8 [C6H3], 128.4, 129.5 [Ph], 129.8 [m, C6H3], 132.9, 136.1 [Ph], 146.9 [CC(CH3)3], 160.0 [m, CCHC]. 31P{1H} NMR (101.3 MHz, C6D6): δ 55.1 [d, 1JRh,P = 144 Hz]. 103Rh NMR (8 MHz, C6D6): δ −6449. Anal. Calcd for C90H90Cl4P4Rh2 (1): C, 65.78; H, 5.52. Found: C, 65.91; H, 5.38. [(4-tBu-2-Ph2P-C6H3)2CH2)RhCl(C5H5N)2] (2). PCP (50.0 mg, 0.076 mmol) and [CODRhCl]2 (18.6 mg, 0.038 mmol) were dissolved in 5 mL of pyridine. The resulting solution was stirred at room temperature for 30 min and filtered, and the volatile components of the solution were removed in vacuo. The remaining orange residue was dried in vacuo for 30 min to give 2 as an orange solid (62.7 mg; 87.8% yield). 1H NMR (250.13 MHz, C6D6): δ 1.03 [s, 18H, CCH3], 3.49 [d, 2JH,H = 13.8 Hz, 1H, CH2,], 6.50−7.40 [m, 26H, Harom], 7.77 [dt, 2JH,H = 13.8, 4JP,H = 2.8 Hz, 1H, CH2], 8.00−8.94 [m, 10H, C5H5N]. 13C{1H} NMR (100.6 MHz, C6D6): δ 31.5 [CCH3], 34.8 [CCH3], 38.0 [CH2], 120.0−137.2 [Carom]. 31P{1H} NMR (101.3 MHz, C6D6): δ 35.7 [dd, 1JRh,P = 202 Hz, cis-2JP,P = 43 Hz, 1P], 43.0 [dd, 1JRh,P = 167 Hz, cis-2JP,P = 43 Hz, 1P]. 103 Rh NMR (8.0 MHz, C 6 D 6 ): δ −7865. Anal. Calcd for C55H56ClN2P2Rh (2): C, 69.88; H, 5.97; N, 2.96. Found: C, 69.70; H, 5.92; N, 2.88. [(4-tBu-2-Ph2P-C6H3)2CH)RhH(C5H5N)(SnCl3)] (3). Pyridine (0.1 mL) was added to a solution of bis(4-tert-butyl-2-(diphenylphosphino)phenyl)methane (50.0 mg, 0.076 mmol) and [(COD)RhCl]2 (18.6 mg, 0.038 mmol) in 5 mL of toluene. The solution was added to SnCl2 (14.3 mg, 0. 076 mmol) and stirred at room temperature for 16 h. The precipitate which formed after the mixture was stored at −40 °C for 3 days was separated and , washed twice with 3 mL of toluene as well as twice with 3 mL of hexane. The remaining residue was dried in vacuo to give 3 as a pale yellow solid (62.7 mg; 78.7% yield). Recrystallization from benzene yielded pale yellow crystals. 1H NMR (400.11 MHz, THF-D8): δ −17.46 [dt, 2JP,H = 11.2 Hz, 1JRh,H = 16.7 Hz; 2JSn,H = 152.7 Hz, 1H], 1.17 [s, 18H, (CCH3)], 5.74 [d, 2JRh,H = 4.0 Hz, 1H, CCHC, 3 JSn,H = 67.2 Hz], 6.58 [m, 2H, py], 7.10 [m, 4 H, Ph], 7.19 [m, 4H, Ph, C6H3], 7.30 [m, 5H, py, Ph], 7.43 [m, 10H, C6H3, Ph], 7.84 [m, 6H, Ph, py]. 13C{1H} NMR (100.6 MHz, THF-D8): δ 30.5 [C(CH3)3] 34.1 [C(CH3)3] 58.4 [d, 1JRh,C = 25.4 Hz, CCHC] 124.1 [py] 125.9, 126.8 [C6H3] 128.0, 128.5, 129.5 [Ph] 129.6 [C6H3] 130.6, 131.5, 133.0, 133.2, 133.9 [Ph1], 136.3 [py] 138.1, 148.7 [C6H3] 153.4 [py] 155.2 [CCHC]. 31P{1H} NMR (101.3 MHz, THF-D8): δ 52.8 [d, 1JRh,P = 111 Hz, 2JSn,P = 289 Hz, 2P]. 103Rh NMR (8,0 MHz, C6D6): δ −8056. 119Sn NMR (186.50 MHz, C6D6): δ 44.7 [ddt, 1JSn,Rh = 424 Hz, 2JSn,P = 289 Hz, 2JSn,H = 152.7 Hz]. Anal. Calcd for C50H51Cl3NP2RhSn C6H5CH3 (3 · C7H8): C, 58.31; H, 5.03; N, 1.27. Found: C, 58.32; H, 5.18; N, 1.30. [(4-tBu-2-Ph2P-C6H3)2CH)RhHCl(2-Me2NC6H4)PH(C6H5)] (4). To a mixture of [(COD)RhCl]2 (11.0 mg, 0.022 mmol) and PCP (28.9 mg, 0.045 mmol) in 10 mL of toluene was added dropwise a toluene solution of HPhPC6H4NMe2 (10.2 mg, 0.044 mmol; in 6 mL). The resulting solution was stirred at room temperature for 16 h and filtered, and the

volatile components were removed in vacuo. The remaining residue was washed with hexane (3 × 7 mL) and dried in vacuo to give 4 as a bright rose solid (40.8 mg; 90% yield). 1H NMR (400.13 MHz, C6D6): δ −15.92 [dddd, 1JRh,H = 22.4 Hz, 2JP,H = 16.0 Hz, 2JP,H = 11.5 Hz, 2JP,H = 11.5 Hz, 1H, RhH], 1.20, 1.22 [s, 18H, (CCH3)], 2.18 [s, 6H, (NCH3)], 6.81−8.33 [m, 37H, Harom, CH, PH]. 13C{1H} NMR (100.6 MHz, C6D6): δ 31.2 [(CCH3)], 34.1, 34.2 [(CCH3)], 44.9 [(NCH3)], 56.1 [dd, 2JP,C = 84 Hz, 1JRh,C = 19 Hz, CH], 120.4−160.1 [Carom]. 31P{1H} NMR (162.0 MHz, C6D6): δ −18.3 [ddd, 1JRh,P = 86 Hz, cis-2JP,P = 26 Hz, 1P], 37.7 [ddd, trans-2JP,P = 386 Hz, 1JRh,P = 115 Hz, cis-2JP,P = 26 Hz, 1P], 50.4 [ddd, trans-2JP,P = 386 Hz, 1JRh,P = 115 Hz, cis-2JP,P = 26 Hz, 1P]. 31P NMR (162.0 MHz, C6D6): δ −18.3 [br dd, 1JP,H = 369 Hz, 1JRh,P = 86 Hz], 37.7 [br dd, trans-2JP,P = 385 Hz, 1JRh,P = 114 Hz], 50.4 [br dd, trans-2JP,P = 386 Hz, 1JRh,P = 116 Hz]. 103Rh NMR (8.0 MHz, C6D6): δ −8090. Anal. Calcd for C59H62ClNP3Rh (4): C, 69.72; H, 6.15; N, 1.38. Found: C, 69.75; H, 6.29; N, 1.36. [(4-tBu-2-Ph2P-C6H3)2CH)RhHCl(PPh2Py)] (5). To a mixture of [(COD)RhCl]2 (11.0 mg, 0.022 mmol) and PCP (28.9 mg, 0.045 mmol) in 10 mL of toluene was added dropwise a toluene solution of diphenyl-2-pyridylphosphine (11.7 mg, 0.044 mmol; in 6 mL). The resulting solution was stirred at room temperature for 16 h and filtered. The volatile components were removed in vacuo. The remaining residue was washed with hexane (3 × 7 mL) and dried in vacuo to give 5 as a bright yellow solid (41.7 mg; 89% yield). 1H NMR (400.13 MHz, C6D6): δ −16.56 [ddt, 1JRh,H = 21.3 Hz, 2JP,H = 17.2 Hz, 2JP,H = 9.9 Hz, 1H, RhH], 1.18 [s, 18H, (CCH3)], 6.34−8.55 [m, 41H, Harom, CH]. 13 C{1H} NMR (100.6 MHz, C6D6): δ 31.1 [(CCH3)], 34.1 [(CCH3)], 57.2 [dd, 2JP,C = 82 Hz, 1JRh,C = 19 Hz, CH], 122.0−159.5 [Carom]. 31 1 P{ H} NMR (162.0 MHz, C6D6): δ 29.5 [dt, 1JRh,P = 87 Hz, cis-2JP,P = 24 Hz, 1P], 35.3 [br, 2P]. 103Rh NMR (8.0 MHz, C6D6): δ −7933. Anal. Calcd for C62H60ClNP3Rh (5): C, 70.89; H, 5.76; N, 1.33. Found: C, 70.98; H, 5.65; N, 1.23. [(4-tBu-2-Ph2P-C6H3)2CH)RhHCl(PPh3)] (6). To a mixture of [(COD)RhCl]2 (11.0 mg, 0.022 mmol) and PCP (28.9 mg, 0.045 mmol) in 10 mL of toluene was added dropwise a toluene solution of PPh3 (11.7 mg, 0.045 mmol; in 6 mL). The resulting solution was stirred at room temperature for 16 h and filtered. The volatile components were removed in vacuo. The remaining residue was washed with hexane (3 × 7 mL) and dried in vacuo to give 6 as a bright yellow solid (42.1 mg; 90% yield). 1H NMR (400.13 MHz, C6D6): δ −16.00 [ddt, 1JRh,H = 20.7 Hz, 2 JP,H = 15.5 Hz, 2JP,H = 10.8 Hz, 1H, RhH], 1.15 [s, 18H, (CCH3)], 6.83−8.11 [m, 42H, Harom, CH]. 13C{1H} NMR (100.6 MHz, C6D6): δ 31.1 [(CCH3)], 34.1 [(CCH3)], 56.8 [dd, 2JP,C = 83 Hz, 1JRh,C = 19 Hz, CH], 125.4−157.8 [Carom]. 31P{1H} NMR (162.0 MHz, C6D6): δ 23.5 [dt, 1JRh,P = 85 Hz, cis-2JP,P = 25 Hz, 1P], 38.6 [dd, 1JRh,P = 116 Hz, cis-2JP,P = 25 Hz, 2P]. 103Rh NMR (8.0 MHz, C6D6): δ −7907. Anal. Calcd for C63H61ClP3Rh (6): C, 72.10; H, 5.86. Found: C, 71.69; H, 5.68. [(4-tBu-2-Ph2P-C6H3)2CH)RhH(NCCH3)(SnB11H11)][Et4N] (7). To a solution of [(COD)RhCl]2 (11.0 mg, 0.022 mmol) and 7 mL of acetonitrile was added dropwise a THF solution of PCP (28.9 mg, 0.045 mmol; in 6 mL) followed by the dropwise addition of an acetonitrile solution of [Et4N]2[SnB11H11] (22.9 mg, 0.045 mmol; in 6 mL). The reaction mixture was stirred at room temperature for 16 h and filtered, and the volatiles were removed in vacuo. The remaining residue was extracted into a mixture of THF and CH3CN. Slow diffusion of diethyl ether afforded 7 (39.2 mg; 75% yield) as yellow crystals. 1H NMR (250.13 MHz, CD3CN): δ −17.54 [dt, 1JRh,H = 18.3 Hz, 2JP,H = 11.9 Hz, 1H, RhH], 1.17 [s, 18H, (CCH3)], 1.23 [tt, 3JH,H = 7.2 Hz, 3JN,H = 1.8 Hz, 12H, NCH2CH3], 3.19 [q, 8H, 3JH,H = 7.3 Hz, NCH2CH3], 5.84 [d, 2 JRh,H = 4.1 Hz, 2J117Sn,H = 53.9 Hz, 2J119Sn,H = 61.4 Hz, 1H, CH], 7.13−7.78 [m, 26H, Harom], The B11H11 protons were not detected due to the line broadening caused by coupling to boron. The CH3CN protons cannot be differentiated from the solvent CH3CN protons. 11B{1H} NMR (80.3 MHz, CD3CN): δ −14.5 [br s, 10B, B2−B11], −9.9 [br s, 1B, B12]. 13 C{1H} NMR (100.6 MHz, CD3CN): δ 6.73 [NCH2CH3], 30.4 [(CCH3)], 34.0 [(CCH3)], 52.1 [NCH2CH3], 53.5 [d, 1JRh,C = 23 Hz, CH], 126.0 [t, JP,C = 9 Hz, Carom], 126.6, 128.2−128.3 [m, Carom], 129.7, 130.1 [Carom], 133.1 [t, JP,C = 6 Hz, Carom], 133.8 [t, JP,C = 7 Hz, Carom], 148.2 [t, JP,C = 3 Hz, Carom], 156.1 [t, JP,C = 17 Hz, Carom]. 31P{1H} NMR F

DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX

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(101.3 MHz, CD3CN): δ 53.6 [d, 1JRh,P = 113 Hz, 2JSn(117)/Sn(119),P = 360 Hz, 2P]. 119Sn{1H} NMR (93.2 MHz, CD3CN) δ −346.6 [br]. 103Rh NMR (8.0 MHz, CD 3 CN): δ −9323. Anal. Calcd for C55H80B11N2P2RhSn·CH3CN (7·C2H3N): C, 56.45; H, 6.90; N, 3.46. Found: C, 56.33; H, 6.49; N, 3.62. [(4-tBu-2-Ph2P-C6H3)2CH)RhH(NCCH3)(GeB11H11)][Et4N] (8). To a solution of [(COD)RhCl]2 (11.0 mg, 0.022 mmol) and 7 mL of acetonitrile was added dropwise a THF solution of PCP (28.9 mg, 0.045 mmol; in 6 mL). Afterward an acetonitrile solution of [Et4N]2[GeB11H11] (27.2 mg, 0.045 mmol; in 6 mL) was added dropwise. The resulting solution was stirred at room temperature for 16 h and filtered. The volatile components were removed in vacuo. The remaining residue was extracted into a mixture of THF and CH3CN. Slow diffusion of diethyl ether afforded 8 (44.7 mg; 89% yield) as yellow crystals. 1H NMR (250.13 MHz, CD3CN): δ −17.37 [dt, 1JRh,H = 18.0 Hz, 2JP,H = 12.6 Hz, 1H, RhH], 1.14 [s, 18H, (CCH3)], 1.23 [tt, 3JH,H = 7.2 Hz, 3JN,H = 1.6 Hz, 12H, NCH2CH3], 3.21 [q, 8H, 3JH,H = 7.3 Hz, NCH2CH3], 5.65 [d, 2JRh,H = 3.2 Hz, 1H, CH], 7.02−7.82 [m, 26H, Harom]. The B11H11 protons were not detected due to the line broadening caused by coupling to boron. The CH3CN protons cannot be differentiated from the solvent CH3CN protons. 11B{1H} NMR (80.3 MHz, CD3CN): δ −13.7 [br s, 10B, B2−B11], −9.7 [br s, 1B, B12]. 13 C{1H} NMR (100.6 MHz, CD3CN): δ 6.8 [NCH2CH3], 30.4 [(CCH3)], 33.9 [(CCH3)], 51.9 [d, 1JRh,C = 24 Hz, CH], 52.1 [t, 1JN,C = 3 Hz, NCH2CH3], 126.0 [t, JP,C = 8 Hz, Carom], 126.4, 127.9−128.0 [m, Carom], 129.5, 129.7, 129.9 [Carom], 133.2 [t, JP,C = 6 Hz, Carom], 134.1 [t, JP,C = 7 Hz, Carom], 147.6 [t, JP,C = 3 Hz, Carom], 156.2 [t, JP,C = 16 Hz, Carom]. 31P{1H} NMR (101.3 MHz, CD3CN): δ 50.8 [d, 1JRh,P = 114 Hz, 2P]. 103Rh NMR (8.0 MHz, CD3CN): δ −9314. Anal. Calcd for C55H80B11GeN2P2Rh·CH3CN (8·C2H3N): C, 58.68; H, 7.17; N, 3.60. Found: C, 58.24; H, 7.38; N, 3.55. General Procedure for the Synthesis of Compounds 9 and 10. To a solution of 0.040 mmol of the respective complexes 5,6 in 8 mL of THF was added dropwise a THF solution of KOtBu (4.5 mg, 0.040 mmol; in 6 mL). Subsequently the reaction mixture was stirred for 1 h at room temperature. The volatile components were removed in vacuo, and the remaining residue was extracted into 10 mL of toluene and the extract filtered. Removal of the solvent (HV) gave the corresponding complexes 9 and 10. The NMR spectra show no evidence of side products or educts. [(4-tBu-2-Ph2P-C6H3)2CH)RhPPh2Py] (9). Orange solid (38.1 mg; 94% yield). 1H NMR (400.13 MHz, C6D6): δ 1.08 [s, 9H, tBuOH], 1.19 [s, 18H, (CCH3)], 6.34−8.55 [m, 41H, Harom, CH], the OH proton was not detected. 13C{1H} NMR (100.6 MHz, C6D6): δ 31.3 [(CCH3)], 34.1 [br, (CCH3)], 55.5 [dd, 2JP,C = 61 Hz, 1JRh,C = 21 Hz, CH], 121.3− 157.2 [Carom]. 31P{1H} NMR (162.0 MHz, C6D6): δ 39.9 [dt, 1JRh,P = 132 Hz, cis-2JP,P = 31 Hz, 1P], 47.2 [dd, 1JRh,P = 168 Hz, cis-2JP,P = 31 Hz, 2P]. 103Rh NMR (7.9 MHz, C6D6): δ −8845. Anal. Calcd for C62H59NP3Rh·tBuOH (9·C4H10O): C, 72.92; H, 6.30; N, 1.29. Found: C, 72.52; H, 6.34; N, 1.32. [(4-tBu-2-Ph2P-C6H3)2CH)RhPPh3] (10). Orange solid (38.1 mg; 94% yield). 1H NMR (400.13 MHz, C6D6): δ 1.26 [s, 18H, (CCH3)], 6.80− 7.73 [m, 41H, Harom, CH]. 13C{1H} NMR (100.6 MHz, C6D6): δ 31.3 [(CCH3)], 33.8 [br, (CCH3)], 55.1 [dd, 2JP,C = 60 Hz, 1JRh,C = 21 Hz, CH], 126.4−157.1 [Carom]. 31P{1H} NMR (162.0 MHz, C6D6): δ 38.0 [dt, 1JRh,P = 131 Hz, cis-2JP,P = 30 Hz, 1P], 45.9 [dd, 1JRh,P = 171 Hz, cis-2JP,P = 30 Hz, 2P]. 103Rh NMR (8 MHz, C6D6): δ −8793. Anal. Calcd for C63H60P3Rh (10): C, 74.70; H, 5.97. Found: C, 74.37; H, 5.90.

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AUTHOR INFORMATION

Corresponding Authors

*E-mail for H.A.M.: [email protected]. *E-mail for L.W.: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank Dr. B. Klüpfel and Prof. Dr. W. Malisch, SCIOMSYN GmbH & Co. KG, for helpful discussion.

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REFERENCES

(1) Jensen, C. M. Chem. Commun. 1999, 2443−2449. (2) Van der Vlugt, J. I. Eur. J. Inorg. Chem. 2012, 2012, 363−375. (3) Van der Boom, M. E.; Milstein, D. Chem. Rev. 2003, 103, 1759− 1792. (4) Montag, M.; Schwartsburd, L.; Cohen, R.; Leitus, G.; Ben-David, Y.; Martin, J. M. L.; Milstein, D. Angew. Chem., Int. Ed. 2007, 46, 1901− 1904. (5) Uhe, A.; Hölscher, M.; Leitner, W. Chem. - Eur. J. 2013, 19, 1020− 1027. (6) Goldberg, J. M.; Wong, G. W.; Brastow, K. E.; Kaminsky, W.; Goldberg, K. I.; Heinekey, D. M. Organometallics 2015, 34, 753−762. (7) Zhu, G.; Wang, L.; Sun, H.; Li, X. RSC Adv. 2015, 5, 19402−19408. (8) Nemeh, S.; Flesher, R. J.; Gierling, K.; Maichle-Mössmer, C.; Mayer, H. A.; Kaska, W. C. Organometallics 1998, 17, 2003−2008. (9) Winter, A. M.; Eichele, K.; Mack, H.-G.; Kaska, W. C.; Mayer, H. A. Organometallics 2005, 24, 1837−1844. (10) Castonguay, A.; Sui-Seng, C.; Zargarian, D.; Beauchamp, A. L. Organometallics 2006, 25, 602−608. (11) Azerraf, C.; Gelman, D. Chem. - Eur. J. 2008, 14, 10364−10368. (12) Azerraf, C.; Gelman, D. Organometallics 2009, 28, 6578−6584. (13) Burford, R. J.; Piers, W. E.; Parvez, M. Organometallics 2012, 31, 2949−2952. (14) Zhu, G.; Li, X.; Xu, G.; Wang, L.; Sun, H. Dalton Trans. 2014, 43, 8595−8598. (15) Zhao, H.; Sun, H.; Li, X. Organometallics 2014, 33, 3535−3539. (16) Burford, R. J.; Piers, W. E.; Ess, D. H.; Parvez, M. J. Am. Chem. Soc. 2014, 136, 3256−3263. (17) Silantyev, G. A.; Filippov, O. A.; Musa, S.; Gelman, D.; Belkova, N. V.; Weisz, K.; Epstein, L. M.; Shubina, E. S. Organometallics 2014, 33, 5964−5973. (18) Comanescu, C. C.; Iluc, V. M. Organometallics 2014, 33, 6059− 6064. (19) Doyle, L. E.; Piers, W. E.; Borau-Garcia, J. J. Am. Chem. Soc. 2015, 137, 2187−2190. (20) Polukeev, A. V.; Marcos, R.; Ahlquist, M. S. G.; Wendt, O. F. Chem. Sci. 2015, 6, 2060−2067. (21) Gelman, D.; Musa, S. ACS Catal. 2012, 2, 2456−2466. (22) Leis, W.; Mayer, H. A.; Kaska, W. C. Coord. Chem. Rev. 2008, 252, 1787−1797. (23) Zhao, J.; Goldman, A. S.; Hartwig, J. F. Science 2005, 307, 1080− 1082. (24) Musa, S.; Filippov, O. A.; Belkova, N. V.; Shubina, E. S.; Silantyev, G. A.; Ackermann, L.; Gelman, D. Chem. - Eur. J. 2013, 19, 16906− 16909. (25) Shaw, B. L. J. Organomet. Chem. 1980, 200, 307−318. (26) Mayer, H. A.; Kaska, W. C. Chem. Ber. 1990, 123, 1827−1831. (27) McLoughlin, M. A.; Flesher, R. J.; Kaska, W. C.; Mayer, H. A. Organometallics 1994, 13, 3816−3822. (28) Dani, P.; Karlen, T.; Gossage, R. A.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 1997, 119, 11317−11318. (29) Lesueur, W.; Solari, E.; Floriani, C.; Chiesi-Villa, A.; Rizzoli, C. Inorg. Chem. 1997, 36, 3354−3362. (30) Vigalok, A.; Uzan, O.; Shimon, L. J. W.; Ben-David, Y.; Martin, J. M. L.; Milstein, D. J. Am. Chem. Soc. 1998, 120, 12539−12544.

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S Supporting Information *

A table, text, and CIF files giving details on crystal structure determinations. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/ acs.organomet.5b00437. G

DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX

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Organometallics (31) Gusev, D. G.; Madott, M.; Dolgushin, F. M.; Lyssenko, K. A.; Antipin, M. Y. Organometallics 2000, 19, 1734−1739. (32) Dani, P.; Toorneman, M. A. M.; van Klink, G. P. M.; van Koten, G. Organometallics 2000, 19, 5287−5296. (33) Van der Boom, M. E.; Iron, M. A.; Atasoylu, O.; Shimon, L. J. W.; Rozenberg, H.; Ben-David, Y.; Konstantinovski, L.; Martin, J. M. L.; Milstein, D. Inorg. Chim. Acta 2004, 357, 1854−1864. (34) Xu, G.; Sun, H.; Li, X. Organometallics 2009, 28, 6090−6095. (35) Lepetit, C.; Poater, J.; Alikhani, M. E.; Silvi, B.; Canac, Y.; Contreras-García, J.; Solà, M.; Chauvin, R. Inorg. Chem. 2015, 54, 2960− 2969. (36) Crocker, C.; Errington, R. J.; McDonald, W. S.; Odell, K. J.; Shaw, B. L.; Goodfellow, R. J. J. Chem. Soc., Chem. Commun. 1979, 498−499. (37) Crocker, C.; Empsall, H. D.; Errington, R. J.; Hyde, E. M.; McDonald, W. S.; Markham, R.; Norton, M. C.; Shaw, B. L.; Weeks, B. J. Chem. Soc., Dalton Trans. 1982, 1217−1224. (38) Gusev, D. G.; Lough, A. J. Organometallics 2002, 21, 2601−2603. (39) Kuznetsov, V. F.; Lough, A. J.; Gusev, D. G. Inorg. Chim. Acta 2006, 359, 2806−2811. (40) Barthes, C.; Lepetit, C.; Canac, Y.; Duhayon, C.; Zargarian, D.; Chauvin, R. Inorg. Chem. 2013, 52, 48−58. (41) Vabre, B.; Canac, Y.; Duhayon, C.; Chauvin, R.; Zargarian, D. Chem. Commun. 2012, 48, 10446−10448. (42) Kuznetsov, V. F.; Abdur-Rashid, K.; Lough, A. J.; Gusev, D. G. J. Am. Chem. Soc. 2006, 128, 14388−14396. (43) Sjoevall, S.; Wendt, O. F.; Andersson, C. J. Chem. Soc., Dalton Trans. 2002, 1396−1400. (44) Gerber, R.; Fox, T.; Frech, C. M. Chem. - Eur. J. 2010, 16, 6771− 6775. (45) Weng, W.; Parkin, S.; Ozerov, O. V. Organometallics 2006, 25, 5345−5354. (46) Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001, 40, 3750−3781. (47) The Chemistry of Pincer Compounds; Jensen, C. M., MoralesMorales, D., Eds.; Elsevier Science: Amsterdam, 2007. (48) Adams, J. J.; Arulsamy, N.; Roddick, D. M. Organometallics 2011, 30, 697−711. (49) Adams, J. J.; Arulsamy, N.; Roddick, D. M. Dalton Trans. 2011, 40, 10014−10019. (50) Adams, J. J.; Lau, A.; Arulsamy, N.; Roddick, D. M. Organometallics 2011, 30, 689−696. (51) Boyd, L. M.; Clark, G. R.; Roper, W. R. J. Organomet. Chem. 1990, 397, 209−218. (52) Paul, G. C.; Gajewski, J. J. Org. Prep. Proced. Int. 1998, 30, 222− 225. (53) Shilov, A. E.; Shul’pin, G. B. Chem. Rev. 1997, 97, 2879−2932. (54) Lindner, E.; Fawzi, R.; Mayer, H. A.; Eichele, K.; Hiller, W. Organometallics 1992, 11, 1033−1043. (55) Moxham, G. L.; Randell-Sly, H.; Brayshaw, S. K.; Weller, A. S.; Willis, M. C. Chem. - Eur. J. 2008, 14, 8383−8397. (56) Kaesz, H. D.; Saillant, R. B. Chem. Rev. 1972, 72, 231−281. (57) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev. 1973, 10, 335−422. (58) Balch, A. L.; Hope, H.; Wood, F. E. J. Am. Chem. Soc. 1985, 107, 6936−6941. (59) Bott, S. G.; Machell, J. C.; Mingos, D. M. P.; Watson, M. J. J. Chem. Soc., Dalton Trans. 1991, 859−862. (60) García, V.; Garralda, M. A.; Hernández, R.; Monge, M. A.; Pinilla, E. J. Organomet. Chem. 1994, 476, 41−46. (61) Bradd, K. J.; Heaton, B. T.; Jacob, C.; Sampanthar, J. T.; Steiner, A. J. Chem. Soc., Dalton Trans. 1999, 1109−1112. (62) Tenn, W. J., III; Conley, B. L.; Bischof, S. M.; Periana, R. A. J. Organomet. Chem. 2011, 696, 551−558. (63) Hayashi, T.; Takahashi, M.; Takaya, Y.; Ogasawara, M. J. Am. Chem. Soc. 2002, 124, 5052−5058. (64) Wilson, A. D.; Miller, A. J. M.; DuBois, D. L.; Labinger, J. A.; Bercaw, J. E. Inorg. Chem. 2010, 49, 3918−3926. (65) Pregosin, P. S. NMR in Organometallic Chemistry; Wiley-VCH: Weinheim, Germany, 2012.

(66) Fleischhauer, S.; Eichele, K.; Schellenberg, I.; Pöttgen, R.; Wesemann, L. Organometallics 2011, 30, 3200−3209. (67) Arras, J.; Eichele, K.; Wesemann, L. Eur. J. Inorg. Chem. 2013, 2013, 5728−5737. (68) APEX2 v2011.8-0; Bruker AXS, Madison, WI, 2011. (69) SAINT V7.68A; Bruker AXS, Madison, WI, 2009. (70) SADABS V2008/1; Bruker AXS, Madison, WI, 2008. (71) Sheldrick, G. M. Acta Crystallogr., Sect. A: Found. Crystallogr. 2008, 64, 112−122. (72) Farrugia, L. J. Appl. Crystallogr. 1999, 32, 837−838. (73) Huebschle, C. B.; Sheldrick, G. M.; Dittrich, B. J. Appl. Crystallogr. 2011, 44, 1281−1284.

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DOI: 10.1021/acs.organomet.5b00437 Organometallics XXXX, XXX, XXX−XXX