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

In Situ Formation of PBiP Ligands upon Complexation of a Mixed Phosphane/Bismuthane with Group 11 Metal Ions Karolin Materne, Santina Hoof, Nicolas Frank, Christian Herwig, and Christian Limberg* Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany S Supporting Information *

ABSTRACT: The behavior of a xanthene derivative with one bismuthane and one phosphane function, Xan(PPh2)(BiPh2), as a ligand toward group 11 metal cations was investigated. It was found that contact with [Cu(MeCN)4]OTf, AgOTf, [Au(PPh3)OTf], in all three cases leads to a transformation of Xan(PPh2)(BiPh2) into a tridentate PBiP system, where a BiPh unit connects two phosphinoxanthyl moieties. In the resulting compounds, [PhBi(Xan(PPh2))2Cu]OTf, 1, [PhBi(Xan(PPh2))2Ag]OTf, 2, and [PhBi(Xan(PPh2))2AuPPh3]OTf, 3, the metal cations are coordinated tetrahedrally by two phosphane donors, one bismuthane donor and a fourth ligand, corresponding to OTf− in case of 1 and 2, or PPh3 in the case of 3. DFT calculations in combination with NBO analysis showed that the bismuth atoms in these PBiP ligands act as σ-donors. 3 thus corresponds to the first known AuI ← BiIII complex.

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INTRODUCTION In order to understand interactions between different metals for instance, in heterogeneous catalysts or multimetallic materials with interesting electronic, magnetic, or luminescent propertiesmolecular compounds containing heterometallic units can provide valuable information. Focusing on bismuth(III) as part of such heterometallic entities, it is noted that only few complexes exist, where a transition metal neighbors Bi directly, and most of them feature a covalent bonding situation (i.e. a metal−metal bond) between the metals.1,3 Some compounds have been isolated, which show that bismuthanes principally can act as donor ligands;2 however their number is rather limited, and because of their reduced donor abilities, bismuthanes were called the Cinderellas among group 15/16 ligands.2b Those bismuthane complexes, which are known, mainly contain group 6−8 central atoms,1,3 and until recently closed-shell M−Bi interactions, for M representing a late transition metal, remained virtually unexplored.4 Schmidbaur et al. reported in 2003 that tertiary bismuthanes (R3Bi) ligands cannot be employed as donor ligands for AuI complexes due to rapid transorganylation processes that give rise to organogold compounds.5 In 2012, we established a different type of bismuth−gold interaction: exploiting the Lewis acidity of BiIII in an ambiphilic PBiP ligand system (Ph2P−C6H4−Bi(Cl)C6H4−PPh2), it was possible to create a Au → Bi unit, that is, a metallophilic interaction in [AuCl(PBiP)], where the AuI center acts as a σ-donor.6 Simultaneously Gabbai ̈ and coworkers published another synthesis for the same gold complex which worked via ligand rearrangement starting from Bi(C6H4o-PPh2)3.7 With the PBiP ligand system and the mentioned derivative with an additional P donor moiety, respectively, also copper(I)/silver(I)···bismuth(III) complexes could be obtained.8 In these, the Bi atom acted predominantly as a © XXXX American Chemical Society

donor ligand, while the Lewis acid character was less pronounced. With the background of this ambivalent behavior of bismuthane functions and the insights gained tethering them with phosphane units in the ligands mentioned above for the complexation of late transition metals, we sought access to further promising bismuthane/phosphane combinations. Bearing in mind the potential of the Xantphos ligands, we were interested to replace (formally) one of the phosphane functions by a bismuthane and to then investigate the coordination properties of the novel potential ligand toward late metals. Recently, we have communicated the synthesis of the phosphino/bismuthino xanthene ligand, Xan(PPh2)(BiPh2), and the hemilabile nature of the bismuthane donor in a palladium(0) complex in O2 activation studies.9 Here we now report the coordination chemistry of Xan(PPh2)(BiPh2) in combination with CuI, AgI, and AuI complex fragments.

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RESULTS AND DISCUSSION In attempts to synthesize a new homoleptic xanthene-based copper(I) complex with metallophilic CuI···BiIII interactions, Xan(PPh2)(BiPh2) was reacted with 0.5 equiv of [Cu(MeCN)4]OTf in a solvent mixture of toluene and acetonitrile at room temperature (Scheme 1). No significant color change was observed. However, the 31 1 P{ H} NMR spectrum, recorded for a THF-d8 solution of the isolated white solid, showed a new singlet signal at −5.1 ppm, which is shifted upfield by around 12 ppm, compared to the signal of the free ligand. This chemical shift is in the range of Received: October 11, 2017

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DOI: 10.1021/acs.organomet.7b00757 Organometallics XXXX, XXX, XXX−XXX

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Organometallics Scheme 1. Synthesis of CuI (1) and AgI (2) Complexes via the Reaction of Xan(PPh2)(BiPh2) with [Cu(MeCN)4]OTf or AgOTf in Toluene and/or Acetonitrile (P = PPh2)

analysis revealed one predominant donor−acceptor interaction between the filled atomic orbital of bismuth (6s) and the empty atomic orbital of copper (4s), resulting in an NBO deletion energy of 30.3 kcal mol−1. Donating interactions in the opposite direction (CuI → BiIII) were also indicated, but the stabilizing energies add up to a total sum of only 9.1 kcal mol−1. In comparison to known copper(I) complexes with dominating BiIII → CuI interactions prepared recently by us8b and the group of Gabbai,̈ 8a the Cu···Bi distance in 1 is shorter and also the donating role of bismuth in 1 is significantly more pronounced resulting in lower ratios between the metal−metal distance and the covalent or van der Waals radii, respectively. The intriguing transformation of Xan(PPh2)(BiPh2) upon contact with CuI posed the question whether this behavior is unique and how the other transition metals from group 11 in the oxidation state of +1 behave. Hence, the P/Bi ligand was treated with 0.5 equiv of silver triflate in toluene (Scheme 1). After workup, a white solid was obtained. Successful complexation of AgI by the P donor of Xan(PPh2)(BiPh2) was indicated by two doublet signals in the 31P{1H} NMR spectrum of a THF-d8 solution, resulting from the coupling of the phosphorus atom with the silver isotopes (δ = 3.4 ppm, 1J(P, 107Ag) = 447 Hz; 1J(P, 109Ag) = 518 Hz). Single crystals could be obtained by diffusion of hexane into a saturated solution of the product in toluene and an X-ray analysis yielded in the molecular structure of the silver(I) complex, [PhBi(Xan(PPh2))2Ag]OTf, 2, as shown in Figure 2. It thus confirms formation of a complex analogous to the product of the conversion of Xan(PPh2)(BiPh2) with copper(I)triflate.

shifts displayed by known copper(I) complexes containing one or more phosphane donors PPh3.10 In the proton NMR spectrum, two separated signals for the methyl groups (δ = 1.60 and 1.74 ppm) of the xanthene backbone were observed, which as in case of the Pd0 complex [(Xan(PPh2)(BiPh2))2Pd]9 indicates a loss of the plane of symmetry through the xanthene backbone. Additionally, it was noted, that an equimolar mixture of Xan(PPh2)(BiPh2) and the CuI salt led to the same NMR spectroscopic observations. Suitable crystals for an X-ray diffraction analysis could be obtained by slow diffusion of hexane into a saturated solution of the product in toluene, and the determined corresponding molecular structure is shown in Figure 1. The complex was

Figure 1. Molecular structure of 1. All hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Bi1···Cu1 2.7902(4), Cu1−O3 2.0992(19), Cu1−P2 2.2466(7), Cu1−P1 2.2628(8), O3−Cu1−P2 113.67(6), O3−Cu1−P1 96.86(6), P2− Cu1−P1 130.63(3), O3−Cu1−Bi1 105.07(6), P2−Cu1−Bi1 107.37(2), P1−Cu1−Bi1 100.30(2).

Figure 2. Molecular structure of 2. All hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Bi1···Ag1 2.9464(3), Ag1−P2 2.4365(7), Ag1−O3 2.441(2), Ag1−P1 2.4615(7), P2−Ag1−O3 116.49(5), P2−Ag1−P1 125.90(2), O3− Ag1−P1 97.16(5), P2−Ag1−Bi1 108.726(19), O3−Ag1−Bi1 98.62(5), P1−Ag1−Bi1 106.243(18).

identified as [PhBi(Xan(PPh2))2Cu]OTf, 1, that is, two equivalents of the ligand Xan(PPh2)(BiPh2) have fused with elimination of BiPh3as indicated by proton NMR spectroscopyand a BiPh unit now connects two xanthene phosphane units that coordinate a CuI ion, which in addition undergoes a contact with a triflate anion. Moreover there is a contact with the bismuth atom, so that, altogether, the copper(I) ion shows a tetrahedral coordination sphere, composed by the two phosphane donors, one triflate anion, and the bismuth(III) atom. The CuI···BiIII distance is 2.7902(4) Å and thus lies between the sum of the covalent radii (2.63 Å, ratio 1.06)11 and the sum of the van der Waals radii (3.47 Å, ratio 0.80).12 Density functional calculations were carried out for 1 to clarify which orbitals are involved in the CuI···BiIII bonding. An NBO

The Ag···Bi distance amounts to 2.9464(4) Å, which is significantly longer than the corresponding Cu···Bi distance. The ratios to the sums of the covalent and the van der Waals radii were determined to be 1.06 and 0.78. Thus, the ratio between the metal···metal distance and the sum of the van der Waals radii decreases from Cu to Ag, while the ratio to the sum of the covalent radii is identical. An NBO analysis revealed for 2 an analogous situation to the one found for 1: there is one dominating interaction between the filled 6s orbital of bismuth and the empty 5s orbital of silver with a calculated NBO deletion energy of 40.0 kcal mol−1. Compared to 1, the donor B

DOI: 10.1021/acs.organomet.7b00757 Organometallics XXXX, XXX, XXX−XXX

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Organometallics character of bismuth is thus stronger in 2. Considering the interactions, in which bismuth acts as the acceptor, the stabilizing energies are in the same range for the complexes 1 and 2 with a slightly lower value of 7.7 kcal mol−1 for 2. Similar to the copper(I) complex 1, the analogous silver complex 2 also possesses the shortest silver···bismuth distance of known bismuth-based AgI complexes in the literature.8 To complete the complexation series concerning group 11 transition metals, the reaction of Xan(PPh2)(BiPh2) toward a AuI fragment was tested. First, [Au(PPh3)OTf] was generated in situ13 and reacted afterward with 2 equiv of Xan(PPh2)(BiPh2) in toluene (Scheme 2). Scheme 2. Synthesis of the Cationic AuI Complex 3 from the Reaction of Xan(PPh2)(BiPh2) with [Au(PPh3)OTf] in Toluene (P = PPh2)

Figure 3. Molecular structure of 3·toluene. The cocrystallized toluene solvent molecule, the triflate anion, and all hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Bi1··· Au1 3.1848(3), Au1−P1 2.3976(12), Au1−P2 2.4075(12), Au1−P3 2.4152(12), P1−Au1−P2 117.60(4), P1−Au1−P3 121.88(4), P2− Au1−P3 113.06(4), P1−Au1−Bi1 100.11(3), P2−Au1−Bi1 96.81(3), P3−Au1−Bi1 100.35(3).

although the NBO deletion energy of 17.7 kcal mol−1 for Bi(6s) → Au(6s) in 3 is significantly smaller, which is understandable as the Au center in 3 has a phosphane instead of triflate as the coligand, so that the Lewis acidity of the metal cation is decreased and there may also be steric clash prohibiting a closer approach between Au and Bi. The sum of the stabilizing energies from interactions of filled Au orbitals with empty Bi orbitals is 7.1 kcal mol−1. The switch from a Au → Bi bond in [AuCl(PBiP)] to a Bi → Au bond in 3 can be rationalized by the fact that the acidity of the σ*(X-Bi) acceptor orbital is governed by the electronegativity of the substituents X,16 so that a ClBi(aryl)2 moiety (i.e., PBiP)) behaves predominantly as an acceptor toward the gold center, while Ph-Bi(aryl)2 (i.e., Xan(PPh2)(BiPh2)) has more donor character. With the formation and characterization of the three compounds 1−3 it has become clear that the transformation of Xan(PPh2)(BiPh2) is a more general phenomenon, at least for the group 11 metal cations. As the first contact within the reaction will lead to complex formation the fusing of two ligand equivalents will probably be initiated by the Lewis acidic character of the metal ion.15 This finds support in the fact that in contact with a Pd0 precursor (with a less acidic metal center) no dismutation of Xan(PPh2)(BiPh2) was observed.9 Future complexation studies with other metal cations will provide more insights.

The 31P{1H} NMR spectrum of the resulting white product, dissolved in THF-d8, showed a new singlet signal at 33.0 ppm, which is in a typical range for AuI complexes coordinated by tertiary phosphanes.6,14 In the proton NMR spectrum, two new signals for the methyl groups (δ = 1.59 and 1.63 ppm) of the xanthene backbone were observed, as for the products 1 and 2. The main signal in the ESI-MS spectrum indicated a mass to charge ratio of 1493.5163, which fits to a complex with the molecular formula of [C76H81AuBiO2P2]+, analogous to the corresponding signals found in the mass spectra of 1 and 2. Single crystals for the X-ray diffraction analysis were grown by diffusion of hexane into a saturated solution of the product in toluene. The molecular structure of the AuI complex, [PhBi(Xan(PPh2))2AuPPh3]OTf, 3, is shown in Figure 3. The AuI ion is surrounded tetrahedrally by the BiIII atom, the phosphorus donors of the xanthene ligands as well as one additional PPh3 ligand originating from the gold precursor; as we observed reproducibly only one signal in the 31P NMR spectrum, we conclude that the resonance for the additional phosphane is coincidently isochronic with the one of PhBi(Xan(PPh2))2, which is reasonable as just one aryl residue differs. Further support for this hypothesis comes from the fact that upon addition of cyanide apart from a signal for PhBi(Xan(PPh2))2 a resonance at −3.7 ppm appears, which we assign to free PPh3. Whereas the complexes 1 and 2 represent uncharged molecules, 3 is an ionic compound. With 3.1848(3) Å the bismuth···gold distance in 3 and also the resulting ratios to the sums of the covalent (1.16) and the van der Waals radii (0.85) are significantly higher than the corresponding values of 1 and 2. DFT calculations were also carried out for complex 3 to clarify which orbitals are involved in the BiIII···AuI bonding. Unlike the only known AuI complex with a dominant AuI → BiIII interaction, [AuCl(PBiP)]6,7 the NBO analysis in 3 revealed mainly interactions in the opposite direction (Bi → Au). This conforms with the computation results for 1 and 2,

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CONCLUSIONS The potential ligand Xan(PPh2)(BiPh2) reacts with CuI, AgI, and AuI precursors to a series of analogous bimetallic complexes 1−3 with predominantly BiIII → MI (M = Cu, Ag, Au) interactions. On going from CuI to AuI the M···Bi bond distances increase, which is consistent with the increase of the ion radius in this order (Chart 1a). Considering the ratio between the metal···metal distances and the covalent or van der Waals radii, it is noticeable that the interactions in compound 3 are significantly weaker than those in 1 and 2 (Chart 1b,c). To our knowledge, complex 3 presents the first (cationic) complex with a defined donor−acceptor interaction with mainly Bi → Au character. C

DOI: 10.1021/acs.organomet.7b00757 Organometallics XXXX, XXX, XXX−XXX

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Organometallics

Chart 1. (a) M−Bi Distances in pm within the Complexes 1, 2, and 3; (b) Ratios between the M−Bi Distance and the Sum of the Covalent Radii; (c) Ratios between the M−Bi Distance and the Sum of the van der Waals Radii

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1424 (s), 1395 (w), 1363 (w), 1307 (m), 1261 (m), 1232 (s), 1210 (s), 1186 (m), 1166 (m), 1096 (m), 1047 (w), 1021 (s), 997 (w), 885 (w), 859 (w), 813 (w), 745 (m), 726 (m), 694 (s), 635 (s), 581 (w) 559 (w), 540 (w), 516 (m), 502 (m), 446 (w) cm−1. Preparation of the AgI Complex, 2. A mixture of Xan(PPh2)(BiPh2) (50.0 mg, 0.058 mmol) and AgOTf (7.4 mg, 0.029 mmol) was dissolved in 4 mL of toluene. After the solution was stirred for 16 h at room temperature, all volatiles were evaporated under reduced pressure. The resulting white solid was dissolved again in 2 mL of toluene, and the cloudy solution was filtered. Subsequently, the colorless filtrate was layered with hexane, and the formation of light yellow crystals was observed. The crystals were isolated via filtration, washed with hexane, and dried in vacuo (yield 44.0 mg, 0.028 mmol, 98%). 31P{1H}-NMR (202.5 MHz, THF-d8): δ = 3.4 (two doublet signals, 1J(P,107Ag) = 447 Hz, 1J(P,109Ag) = 518 Hz). 1H NMR (500.1 MHz, THF-d8): δ = 7.70−7.65 (m, 6H, 2 CH-Xan, 4 CH-PPh2), 7.43−7.40 (m, 4H, CH-Xan), 7.32−7.19 (m, 10H, 4 CH-BiPh, 6 CHPPh2), 7.17−7.11 (m, 7H, 1 CH-BiPh, 6 CH-PPh2), 7.00−6.96 (m, 4H, CH-PPh2), 6.63−6.60 (m, 2H, CH-Xan), 1.72 (s, 6H, CH3-Xan), 1.63 (s, 6H, CH3-Xan), 1.13 (s, 18H, (CH3)3-Xan), 1.12 (s, 18H, (CH3)3-Xan). 19F-NMR (470.6 MHz, THF-d8): δ = −79.1 ppm. Anal. (%) Calcd for C77H81AgBiF3O5P2S (1554.32 g·mol−1): C, 59.50; H, 5.25; S, 2.06. Found: C, 59.96; H, 5.65; S, 1.84. ESI-MS (pos): m/z calcd for [C76H81BiAgO2P2]+ 1403.4561, found 1403.4618. ATR-FTIR (C6D6): ν̃ = 2956 (m), 1477 (w), 1422 (s), 1362 (w), 1292 (m), 1260 (m), 1235 (s), 1186 (w), 1157 (m), 1093 (w), 1024 (m), 886 (w), 861 (w), 811 (w), 744 (m), 727 (w), 693 (m), 636 (m), 516 (w), 499 (m) cm−1. Preparation of the AuI Complex, 3. [Au(PPh3)OTf] was performed in situ by the reaction of [Au(PPh3)Cl] (28.5 mg, 0.058 mmol) and AgOTf (14.8 mg, 0.058 mmol) in 4 mL of toluene. After the solution was stirred for 16 h at room temperature, the reaction mixture was filtered, and a solution of Xan(PPh2)(BiPh2) (100 mg, 0.115 mmol) in 8 mL of toluene was added to the colorless filtrate. It was stirred for an additional 16 h, and all volatiles were evaporated under reduced pressure. The white residue was dissolved in 4 mL of toluene again, followed by filtration. The solution of the crude product was overlaid with hexane resulting in the formation of colorless crystals. The crystals were isolated via filtration, washed with hexane, and dried in vacuo (yield 97.3 mg, 0.049 mmol, 84%). 31P{1H}-NMR (162.0 MHz, THF-d8): δ = 33.0. 1H NMR (400.1 MHz, THF-d8): δ = 7.77 (d, 4J(H,H) = 2.3 Hz, 2H, CH-Xan), 7.44−7.09 (m, 42H, 4 CHXan, 20 CH-PPh2, 15 CH-PPh3, 3 CH-BiPh), 7.01−6.98 (m, 2H, CHBiPh), 6.55−6.51 (m, 2H, CH-Xan), 1.64 (s, 6H, CH3-Xan), 1.60 (s, 6H, CH3-Xan), 1.16 (s, 18H, (CH3)3-Xan), 1.11 (s, 18H, (CH3)3Xan). 19F-NMR (282.4 MHz, THF-d8): δ = −80.1 ppm. Anal. (%) Calcd for C95H96AuBiF3O5P3S·C7H8 (1997.84 g·mol−1, pestled crystals were analyzed): C, 61.32; H, 5.25; S, 1.60. Found: C, 61.71; H, 5.27; S, 1.49. ESI-MS (pos): m/z calcd for [C76H81BiAuO2P2]+ 1493.5176, found 1493.5163. ATR-FTIR (THF): ν̃ = 3058 (w), 2960 (m),1478 (w), 1422 (s), 1363 (w), 1263 (s), 1223 (w), 1186 (w), 1143 (m), 1094 (m), 1031 (s), 998 (w), 886 (w), 858 (w), 804 (w), 746 (m), 694 (s), 637 (s), 517 (m), 502 (m) cm−1.

EXPERIMENTAL SECTION

General Considerations. All manipulations were carried out in a glovebox or by means of Schlenk-type techniques involving the use of a dry and oxygen-free argon atmosphere. All solvents were dried by an MBraun SPS solvent purification system prior to use. AgOTf (ABCR), [Au(PPh3)Cl] (ABCR), and [Cu(MeCN)4]OTf (Sigma-Aldrich) were obtained commercially. [Au(PPh3)OTf] was synthesized by the reaction of [Au(PPh3)Cl] and AgOTf following a modified literature procedure.13 The 1H, 31P, and 19F NMR spectra were recorded on a Bruker DPX 300, AV 400 or AV 500 (1H, 300.1, 400.1, 500.1 MHz; 31P, 121.5, 162.0, 202.5 MHz; 19F, 282.4, -, 470.6 MHz) spectrometer in dry degassed THF-d8 as solvent. The spectra were calibrated against the internal residual proton resonances (THF-d8, δ = 1.72 or 3.58 ppm). Chemical shifts of 31P nuclei were referenced externally to H3PO4, and those for 19F nuclei to CFCl3. The following abbreviations are used for the peak multiplicities: s, singlet; d, doublet; t, triplet; m, multiplet; br, broad signal. Mass spectra (ESI) were recorded on an Agilent Technologies 6210 time-of-flight LC-MS instrument. The purity of all new compounds has been established by Elemental analysis, which were performed on a HEKAtech Euro EA 3000 elemental analyzer. Infrared (IR) spectra were recorded with a Shimadzu FTIR-8400s spectrometer using solid samples prepared as KBr pellets. ATR spectra were performed with a Bruker ALPHA Platinum ATR spectrometer. Preparation of Xan(PPh2)(BiPh2). The ligand was prepared according to literature procedure.9 For an NMR spectroscopic comparison of Xan(PPh2)(BiPh2) with the complexes 1, 2, and 3, additional NMR spectroscopic data of the ligand in THF-d8 are given here. 31P{1H}-NMR (162.0 MHz, THF-d8): δ = −16.7. 1H NMR (400.1 MHz, THF-d8): δ = 7.64−7.61 (m, 4H, CH-Ph), 7.51 (d, 4 J(H,H) = 2.2 Hz, 1H, CH-Xan), 7.48 (d, 4J(H,H) = 2.2 Hz, 1H, CHXan), 7.40 (d, 4J(H,H) = 2.2 Hz, 1H, CH-Xan), 7.29−7.23 (m, 14H, CH-Ph), 7.23−7.17 (m, 2H, CH-Ph), 6.53 (dd, 3J(P,H) = 4.5 Hz, 4 J(H,H) = 2.2 Hz, 1H, CH-Xan), 1.66 (s, 6H, CH3-Xan), 1.11 (s, 9H, (CH3)3-Xan), 1.10 (s, 9H, (CH3)3-Xan) ppm. Preparation of the CuI Complex, 1. Xan(PPh2)(BiPh2) (40.0 mg, 0.046 mmol) was dissolved in 3 mL of toluene, and a solution of [Cu(MeCN)4]OTf (8.7 mg, 0.023 mmol) in 1 mL of acetonitrile was added. The reaction mixture was stirred for 16 h at room temperature. After removing the solvent the oily, colorless residue was dissolved in 2 mL of toluene and filtered. The filtrate was overlaid with hexane. The resulting light yellow crystals were washed with hexane and dried in vacuo (quantitative yield). 31P{1H}-NMR (202.5 MHz, THF-d8): δ = −5.1. 1H NMR (500.1 MHz, THF-d8): δ = 7.66−7.59 (m, 6H, 2 CHXan, 4 CH-PPh2), 7.42−7.38 (m, 4H, CH-Xan), 7.35−7.32 (m, 2H, CH-PPh2), 7.28−7.20 (br, 6H, CH-PPh2), 7.17−7.07 (m, 6H, 4 CHPPh2, 2 CH-BiPh), 6.90−6.78 (br, 7H, 4 CH-PPh2, 3 CH-BiPh), 6.58−6.54 (br, 2H, CH-Xan), 1.74 (s, 6H, CH3-Xan), 1.60 (s, 6H, CH3-Xan), 1.12 (s, 18H, (CH3)3-Xan), 1.11 (s, 18H, (CH3)3-Xan). 19 F-NMR (470.6 MHz, THF-d8): δ = −78.6 ppm. Anal. (%) Calcd for C77H81BiCuF3O5P2S (1510.00 g·mol−1): C, 61.25; H, 5.41; S 2.12. Found: C, 61.53; H 5.51; S, 2.02. ESI-MS (pos): m/z calcd for [C76H81BiCuO2P2]+ 1359.4806, found 1359.4839. ATR-FTIR (THF): ν̃ = 3056 (w), 2961 (m), 2905 (w), 2869 (w), 1478 (w), 1463 (w), D

DOI: 10.1021/acs.organomet.7b00757 Organometallics XXXX, XXX, XXX−XXX

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(9) Materne, K.; Braun-Cula, B.; Herwig, C.; Frank, N.; Limberg, C. Chem. - Eur. J. 2017, 23, 11797−11801. (10) Kräuter, T.; Neumüller, B. Polyhedron 1996, 15, 2851−2857. (11) Pyykkö, P.; Atsumi, M. Chem. - Eur. J. 2009, 15, 186−197. (12) (a) Bondi, A. J. Phys. Chem. 1964, 68, 441−451. (b) Mantina, M.; Chamberlin, A. C.; Valero, R.; Cramer, C. J.; Truhlar, D. G. J. Phys. Chem. A 2009, 113, 5806−5812. (13) Zhang, J.; Yang, C.-G.; He, C. J. Am. Chem. Soc. 2006, 128, 1798−1799. (14) (a) Wade, C. R.; Gabbaï, F. P. Angew. Chem., Int. Ed. 2011, 50, 7369−7372. (b) Pintado-Alba, A.; de la Riva, H.; Nieuwhuyzen, M.; Bautista, D.; Raithby, P. R.; Sparkes, H. A.; Teat, S. J.; López-deLuzuriaga, J. M.; Lagunas, M. C. Dalton Trans. 2004, 3459−3467. (15) Freedman, L. D.; Doak, G. O. Chem. Rev. 1982, 82, 15−57. (16) Tschersich, C.; Hoof, S.; Frank, N.; Herwig, C.; Limberg, C. Inorg. Chem. 2016, 55, 1837−1842.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.7b00757. NMR spectra, crystallographic data for 1−3, and details concerning the DFT calculations (PDF) Cartesian coordinates for the optimized structures 1−3 (XYZ) Accession Codes

CCDC 1579097−1579099 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

* Tel: +4930-20937382. E-mail: [email protected]. ORCID

Christian Limberg: 0000-0002-0751-1386 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank the DFG (LI 714/8-1) for funding as well as the Humboldt-Universität zu Berlin. REFERENCES

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DOI: 10.1021/acs.organomet.7b00757 Organometallics XXXX, XXX, XXX−XXX