Gold and silver hydrides: synthesis of heterobimetallic iridium-M (M = gold, silver) complexes and x-ray crystal structures of (PPh3)Au(.mu.-H)IrH2(PPh3)3 and (PPh3)Ag(.mu.-H)IrH2(PPh3)3 (original) (raw)
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Angewandte Chemie International Edition, 2013
Coinage metal hydrides continue to attract attention because of their interesting structural and physical properties, as well as for their role as reagents or intermediates in the transformation of organic substrates. For example, several copper hydride compounds have been structurally characterized and developed as catalysts for 1,4 reduction reactions of enones and for hydrocupration of alkynes. [1] In contrast, whereas their heavier congeners have been implicated as reactive intermediates in oxidation and other reactions, and have been characterized in the gas phase, as well as by matrix isolation experiments, [4] few silver and gold hydride compounds have been synthesized and structurally characterized by X-ray crystallography. We have been examining the role of coinage-metal cluster compounds in CÀC bond coupling reactions, [6] click chemistry, and C À X bond activation of organic substrates. In our work, methods based on mass spectrometry (MS) are employed to explore cluster formation and reactivity, and to direct condensed phase synthesis and characterization of novel clusters. As part of this cluster chemistry program, we became interested in extending the method of generating bis(phosphino)-protected gold nanoclusters by sodium borohydride reduction of gold salts [10] to generate related silver nanoclusters. Herein, we report on the serendipitous MSbased discovery of a novel silver hydride cluster, [Ag 3 HClL 3 ] + (L = bis(phosphino) ligand), which has prompted its massspectrometry-directed synthesis and X-ray and neutron crystallographic structural characterization, which reveal a {Ag 3 (m 3 -H)(m 3 -Cl)} + core structure. The gas-phase reactivity of this cluster is also explored.
Inorganic Chemistry, 1984
Reaction of [(dipho~)Rh(acetone)~]BF~ with mer,truns-IrHC12L3 (L = PMe2Ph, PEt2Ph, PEt3; diphos = Ph2PCH2CH2PPh2) affords the hydridebridged dinuclear complexes [(diphos)Rh(p-H)(p-Cl)IrCIL,] BF4. Solution studies show that the bridging ligands are only weakly coordinated to the rhodium. The molecular structure of 3 (L = PEt3) has been determined by X-ray diffraction: monoclinic, space group P21/c, 2 = 4, a = 11.786 (2) A, b = 19.673 (4) A, c = 22.571 (4) A, @ = 89.88 (1)O. The structure was solved by Patterson and Fourier methods using 5750 observed reflections [I 2 3u(Z)] and refined to a conventional R = 0.057. The coordination around rhodium is distorted square planar and that around iridium is distorted octahedral. The Rh-Ir distance is 2.903 (1) A, and the bridging chlorine atom is almost symmetrically bonded to the metals (Rh-Cl = 2.386 (3), Ir-CI = 2.381 (3) A). The isoelectronic complex [(diph~s)Rh(p-H)(p-Cl)IrH(PEt,)~]BF~ was obtained in a similar reaction, starting from mer,~is-IrH~Cl(PEt,)~. Its structure determined by X-ray diffraction, as above, is monoclinic, space group P21, Z = 2, a = 11.102 (2) A, b = 13.582 (3) A, c = 16.694 (4) A, @ = 85.06 (2)'. The final agreement factor (for the 4553 observed reflections) R is 0.062. As for compound 3 the coordination around Rh and Ir is distorted square planar and octahedral, respectively. There is a pronounced asymmetry in the chlorine bridge (Rh-Cl = 2.394 (5), Ir-Cl = 2.510 (5) A), and the metal-metal separation is 2.969 (2) A. t o the synthesis of cationic Rh(1)-Ir(II1) complexes. Experimental Section All operations were carried out under purified nitrogen. Solvents were distilled under nitrogen and dried prior to use. Elemental analyses were formed by the Microanalytical Section of the Swiss Federal Institute of Technology. Infrared spectra in the region 4000-400 cm-' were recorded on a Beckman IR 4250 spectrophotometer as KBr pellets or Nujol mulls. The IH and 31P{'HJ NMR spectra were recorded at 90.00 and/or 250.00 and 36.43 MHz, respectively, on a FT Bruker WH-90 or F T Bruker 250 instrument. 'H and chemical shifts are given relative to external (CH3)$i and H3P04, respectively. A positive sign denotes a shift downfield of the reference. A. Syntheses. [Rh(dipho~)(nbd)]BF,~ (nbd = norbornadiene), mer,truns-IrHCl2L3 (L = PMe2Ph, PEt2Ph, PEt3),9 and mer,cis-IrHCl2(PMePh2),,Io were prepared according to literature methods. For the preparation of mer,cis-IrH,CI(PEt,),, a toluene solution of [ (~o c)~I r C l ]~ (coc = cyclooctadiene) was reacted with 3 equiv of PEt,, and hydrogen was bubbled through the solution for 10 min, leading almost quantitatively to the product. (a) ETH-Zcntrum. (b) Taken in Dart from the Ph.D. thesis of H.L. (c)
Inorganic Chemistry, 1984
Reaction of [(dipho~)Rh(acetone)~]BF~ with mer,truns-IrHC12L3 (L = PMe2Ph, PEt2Ph, PEt3; diphos = Ph2PCH2CH2PPh2) affords the hydridebridged dinuclear complexes [(diphos)Rh(p-H)(p-Cl)IrCIL,] BF4. Solution studies show that the bridging ligands are only weakly coordinated to the rhodium. The molecular structure of 3 (L = PEt3) has been determined by X-ray diffraction: monoclinic, space group P21/c, 2 = 4, a = 11.786 (2) A, b = 19.673 (4) A, c = 22.571 (4) A, @ = 89.88 (1)O. The structure was solved by Patterson and Fourier methods using 5750 observed reflections [I 2 3u(Z)] and refined to a conventional R = 0.057. The coordination around rhodium is distorted square planar and that around iridium is distorted octahedral. The Rh-Ir distance is 2.903 (1) A, and the bridging chlorine atom is almost symmetrically bonded to the metals (Rh-Cl = 2.386 (3), Ir-CI = 2.381 (3) A). The isoelectronic complex [(diph~s)Rh(p-H)(p-Cl)IrH(PEt,)~]BF~ was obtained in a similar reaction, starting from mer,~is-IrH~Cl(PEt,)~. Its structure determined by X-ray diffraction, as above, is monoclinic, space group P21, Z = 2, a = 11.102 (2) A, b = 13.582 (3) A, c = 16.694 (4) A, @ = 85.06 (2)'. The final agreement factor (for the 4553 observed reflections) R is 0.062. As for compound 3 the coordination around Rh and Ir is distorted square planar and octahedral, respectively. There is a pronounced asymmetry in the chlorine bridge (Rh-Cl = 2.394 (5), Ir-Cl = 2.510 (5) A), and the metal-metal separation is 2.969 (2) A. t o the synthesis of cationic Rh(1)-Ir(II1) complexes. Experimental Section All operations were carried out under purified nitrogen. Solvents were distilled under nitrogen and dried prior to use. Elemental analyses were formed by the Microanalytical Section of the Swiss Federal Institute of Technology. Infrared spectra in the region 4000-400 cm-' were recorded on a Beckman IR 4250 spectrophotometer as KBr pellets or Nujol mulls. The IH and 31P{'HJ NMR spectra were recorded at 90.00 and/or 250.00 and 36.43 MHz, respectively, on a FT Bruker WH-90 or F T Bruker 250 instrument. 'H and chemical shifts are given relative to external (CH3)$i and H3P04, respectively. A positive sign denotes a shift downfield of the reference. A. Syntheses. [Rh(dipho~)(nbd)]BF,~ (nbd = norbornadiene), mer,truns-IrHCl2L3 (L = PMe2Ph, PEt2Ph, PEt3),9 and mer,cis-IrHCl2(PMePh2),,Io were prepared according to literature methods. For the preparation of mer,cis-IrH,CI(PEt,),, a toluene solution of [ (~o c)~I r C l ]~ (coc = cyclooctadiene) was reacted with 3 equiv of PEt,, and hydrogen was bubbled through the solution for 10 min, leading almost quantitatively to the product. (a) ETH-Zcntrum. (b) Taken in Dart from the Ph.D. thesis of H.L. (c)
Synthesis and X-ray structures of cyclometalated iridium complexes including the hydrides
Dalton Trans., 2013
Cyclometalation of [Cp*IrCl 2 ] 2 with ketimine ligands generated very active catalysts for transfer hydrogenation of imines as well as reductive amination. The synthesis and X-ray diffraction structures of three such complexes are disclosed in this paper. The hydrides of two complexes, key intermediates in hydrogenation, have been isolated and their structures determined by X-ray diffraction as well.
Synthesis and characterization of new pentamethylcyclopentadienyl iridium hydride complexes
Journal of Organometallic Chemistry, 2012
Pentamethylcyclopentadienyl iridium dihydride complexes [Cp*Ir(H) 2 (PR 3 )]; (PR 3 ¼ PPh 2 Me, PTA) were prepared by reaction of [Cp*IrCl 2 (PPh 2 Me)] and [Cp*IrCl 2 (PTA)], respectively, with an excess of sodium bis(2-methoxyethoxy)aluminium hydride (Red-Al). Protonation of the dihydride [Cp*Ir(H) 2 (PPh 2 Me)] with HBF 4 $Et 2 O at low temperature gave the classical trihydride complex [Cp*Ir(H) 3 (PPh 2 Me)]BF 4 that displays quantum mechanical exchange coupling. Reaction of [Cp*IrCl 2 (PPh 2 Me)] with CO gave the halfsandwich iridium carbonyl compound [Cp*IrCl(CO)(PPh 2 Me)]Cl which, by reaction with NaBPh 4 , yielded yellow microcrystals of [Cp*IrCl(PPh 2 Me)(CO)]BPh 4 adequate for X-ray diffraction analysis.
Journal of the American Chemical Society
The synthesis of new families of stable or at least spectroscopically observable gold(III) hydride complexes is reported, including anionic cis-hydrido chloride, hydrido aryl, and cis-dihydride complexes. Reactions between (C^C)AuCl-(PR 3) and LiHBEt 3 afford the first examples of gold(III) phosphino hydrides (C^C)AuH(PR 3) (R = Me, Ph, p-tolyl; C^C = 4,4′-di-tert-butylbiphenyl-2,2′-diyl). The X-ray structure of (C^C)AuH(PMe 3) was determined. LiHBEt 3 reacts with (C^C)AuCl(py) to give [(C^C)Au(H)Cl] − , whereas (C^C)-AuH(PR 3) undergoes phosphine displacement, generating the dihydride [(C^C)AuH 2 ] −. Monohydrido complexes hydroaurate dimethylacetylene dicarboxylate to give Z-vinyls. (C^N^C)Au pincer complexes give the first examples of gold(III) bridging hydrides. Stability, reactivity and bonding characteristics of Au(III)−H complexes crucially depend on the interplay between cis and trans-influence. Remarkably, these new gold(III) hydrides extend the range of observed NMR hydride shifts from δ −8.5 to +7 ppm. Relativistic DFT calculations show that the origin of this wide chemical shift variability as a function of the ligands depends on the different ordering and energy gap between "shielding" Au(d π)-based orbitals and "deshielding" σ(Au−H)-type MOs, which are mixed to some extent upon inclusion of spin−orbit (SO) coupling. The resulting 1 H hydride shifts correlate linearly with the DFT optimized Au−H distances and Au−H bond covalency. The effect of cis ligands follows a nearly inverse ordering to that of trans ligands. This study appears to be the first systematic delineation of cis ligand influence on M−H NMR shifts and provides the experimental evidence for the dramatic change of the 1 H hydride shifts, including the sign change, upon mutual cis and trans ligand alternation.
Organometallics, 2012
The new iridium−gold complex Ir 4 (CO) 11 (Ph)(μ-AuPPh 3), 1 was obtained from the reaction of the tetrairidium anion [Ir 4 (CO) 11 (Ph)] − with [Au(PPh 3)][NO 3 ]. Two new iridium−gold complexes Ir 4 (CO) 10 (AuPPh 3) 2 , 2, and Ir 4 (CO) 11 (AuPPh 3) 2 , 3, were obtained from the reaction of [HIr 4 (CO) 11 ] − with [Au(PPh 3)][NO 3 ]. Compounds 1−3 were structurally characterized by single crystal X-ray diffraction analyses. Compound 2 adds CO reversibly to form compound 3. In this process, the octahedral Ir 4 Au 2 cluster of 2 is converted into the Au(PPh 3)-capped Ir 4 Au trigonal bipyramidal cluster found in 3. Compounds 2 and 3 have been investigated by DFT computational analyses in order to understand the metal−metal bonding and the mechanism of their interconversion by CO addition and elimination. Compound 2 adds PPh 3 to form the compound Ir 4 (CO) 10 (PPh 3)-(AuPPh 3) 2 , 4, which is structurally similar to 3. Compound 4 loses CO and benzene when heated to form the compound Ir 4 (CO) 9 (μ 3-PPhC 6 H 4)(AuPPh 3) 2 , 5, which contains a triply bridging PPhC 6 H 4 ligand.
Organometallics, 1994
Reactions of the dinuclear derivative [Au2(p-CHzPPh&H2)23 with [AuL2lC104 (L = PPh3, PPhaMe, tht) or Q[AuX21 (X = C1, Q = N(PPh&; X = Br, Q = PPhsBz), in a 1:2 molar ratio, proceed with partial transfer of the bis(y1ide) ligand to afford the cationic or anionic derivatives [ A u~(~-C H~P P~~C H~) L~] C~O~ (L = PPh3, PPhZMe, tht) or Q[Au2(p-CH2PPh2CH2)X2] (X = C1, Q = N(PPh3)z; X = Br, Q = PPhsBz), respectively. When [Au(PPh&IC104 is used and the reaction is performed in a 1:l molar ratio, the trinuclear derivative [Au3(p2-CHzPPhzCH2)2-(PPh3)21 C104 is obtained. Complexes [ A U~(~-C H~P P~~C H~) L~I C~O~ (L = PPh3, tht) can be also obtained by reaction of Q [ A U~(~-C H~P P~~C H~) X~] (X = C1, Br) with [Ag(OC103)L] (L = PPh3, tht), and the anionic derivative [N(PPh&I [ A U~(~-C H~P P~~C H~) C W undergoes oxidative addition of chlorine to give the gold(I1) compound [N(PPh&I [Auz(p-CHzPPh&H2)ClJ. The structure of [ A u~(~& H z P P~~C H~)~( P P~~)~~T C N Q has been determined by a single-crystal X-ray diffraction study. It crystallizes in the space group P i with a = 12.221(3) A, b = 13.220(3) A, c = 22.690(5) A, CY = 98.12(2)", p = 91.39(2)', y = 115.76(2)",2= 2 (at -95 "C). Intramolecular Aw-Au contacts of 3.391 and 3.544 A are observed. * Abstract published in Aduance ACS Abstracts, March 1, 1994. (1) (a) Muetterties, E. L.; Rhodin, T. N.; Band, E.; Brucker, C. F.; Pretzer, W. R. Chem. Rev. 1979, 79, 91. (b) Rumin, R.; Courtot, P.; Guerchais, J. E.; Petillon, F. Y.; Manojlovic-Muir, L.; Muir, K. W. J. Organomet. Chem. 1986,301, C1. (2) (a) Brown, J. M.; Pearaon, M.; Jastrzebski, J. T. B.H.; van Koten, G. J. Chem. SOC., Chem. Common. 1992,1440. (b) Braunstein, P.; Knorr, M.; Hirle, B.; Reinhard, G.; Schubert, U. Angew. Chem., Znt. Ed. Engl. 1992,31,1583. (3) Lin, I. J. B.; Liu, C. W.; Liu, L.; Wen, Y. Organometallics 1992,11, 1447. (11) (a) Schmidbaur, H.; Mandl, J. R. Angew. Chem., Znt. Ed. Engl. 1977,16,640. (b) Schmidbaur, H.; Mandl, J. R.; Basset, J. M.; Blaschke, G.; Zimmer-Gasser, B. Chem. Ber. 1981,114,433. (12) (a) Schmidbaur, H.; Franke, R. Angew. Chem., Znt. Ed. Engl. 1973,12,416. (b) Schmidbaur, H.; Mandl, J. R.; Richter, W.; Bejenke, V.; Franck, A.; Huttner, G. Chem. Ber. 1977,110,2236. (c) Schmidbaur, H.; Scherm, H. P.; Schubert, U. Chem. Ber. 1978,111, 764. (13) (a) Basil, J. D.; Murray, H. H.; Fackler, J. P., Jr.; Tocher, J.; Mazany, A. M.; Trzcinska-Bancroft, B.; Knachel, H.; Dudis, D.; Delord, T. J.; Marler, D. 0. J. Am. Chem. SOC. 1986,107,6908. (b) Clark, R. J. H.; Tocher, J. H.; Fackler, J. P.; Neira, R.; Murray, H. H.; Knachel, H.
Organometallics, 1982
crystal was mounted on the goniometer head with its long dimension nearly parallel to the phi axis of the diffractometer. A total of 8327 independent reflections having 2@MoK& 55' (the equivalent of 1.0 limiting Cu Ka spheres) were measured in two concentric shells of increasing 28, each of which contained approximately 4150 reflections. A scanning rate of 6'/min was used for all others. Each of these 1.1' wide scans were divided into 19 equal (time) intervals, and those 13 contiguous intervals which had the highest single accumulated count at their midpoint were used to calculate the net intensity from scanning. Background counta, each lasting for one-fourth the total time used for the net scan (13/19 of the total scan time), were measured at u settings 1.1' above and below the calculated Kn doublet value for each reflection. Since $ scans for several intense reflections confirmed the anticipated absence of variable absorption for this sample, the intensities were reduced without absorption corrections to relative squared amplitudes, Fd2, by meana of appropriate Lorentz and polarization corrections. The structure was solved by using the "heavy-atom" technique. Unitweighted full-matrix least-squares refinement which utilized anisotropic thermal parameters for all 39 crystallographically independent nonhydrogen atoms converged to R1 (unweighted, based on flu = 0.046 and Rz (weighted, based on flu = 0.057 for 3482 independent reflections having 28-< 4 3 ' and I > 3a(Z). A difference Fourier synthesis at this point permitted the location of all 59 hydrogen atoms in the asymmetric unit. All additional least-squares cycles for 1 refined hydrogen atoms with isotropic thermal parameters and nonhydrogen atoms with anisotropic thermal parameters. Unit-weighted cycles gave R1 = 0.023 and R2 = 0.025 with 3482 reflections. Similar unit-weighted refinement cycles with the more complete (2@MoKa < 55') data set gave R1 = 0.028 and Rz = 0.029 for 6133 reflections. The final cycles of empirically ~eighted'~ full-matrix least-squares refinement with (48) The R values are defined as Rl = xIIFoI-~F c~~/~~F o~ and Rz = {xw(pol-. pc1)2/FylFo12f/z, where w is the weight given each reflection. The function mmmlzed I xw(lFol-I(IFc1)2, where K is the scale factor. 98 independent atoms gave R1 = 0.028 and R2 = 0.034 for 6133 independent reflections having 2 @ h m < 55' and I > 3a(I). Since a careful comparison of final Fo and F, values22 indicated the absence of extinction effeds, extinction corrections were not made. All structure factor calculations employed recent tabulations of atomic form factorsub and anomalous dispersion corrections4Bc to the scattering factors of the Rh and P atoms. All calculations were performed on a Data General Eclipse 5-2 0 computer with 65K of 16-bit words, a floating point processor for 32-and 64-bit arithmetic and versions of the Nicolet E-XTL interactive crystallographic software package as modified at Crystalytics Co. Acknowledgment. This research was supported by the National Science Foundation. E.L.M. is indebted t o the Miller Institute for Basic Research in Science for a grant in the form of a Miller Professorship. R.R.B. is the recipient of a National Science Foundation Graduate Fellowship (197S1982). The rhodium chloride was furnished on a loan grant through the generosity of Johnson Matthey, Inc. We thank R. Hoffmann for helpful suggestions.