Ian D. Salter

Metal framework arrangements in pentanuclear gold-ruthenium clusters. Crystal structures of [Au2Ru3(μ3-S)(CO)8(PPh3)3] and [Au2Ru3(μ-H)(μ3-COMe)(CO)9(PPh3)2]

Abstract Reaction between the compounds [AuMe(PPh3)] and [Ru3(μ-H)2(μ3-S)(CO)9] in toluene affords a mixture of products [AuRu3(μ-H)(μ3-S)(CO)8(PPh3)L] [Ru3(μ-H)2(μ3-S)(CO)7(PPh3)L], and Au2Ru3(μ3-S)(CO)8(PPh3)2L] (L = CO pr PPh3). The molecular structure of [Au2Ru3(μ3-S)(CO)8(PPh3)3] has been established by a single-crystal X-ray diffraction study. The Au2Ru3 metal atom core adopts a trigonal bipyramidal structure, with gold atoms occupying equatorial and apical sites. In contrast, in the species [Au2Ru3(μ-H)(μ3-COMe)(CO)9(PPh3)2], also studied by X-ray diffraction, the metal atoms have a distorted square pyramidal structure with a ruthenium atom at the apex. These structural studies allow interpretation of the dynamic behaviour of [Au2Ru3(μ3-S)(CO)8(PPh3)3], observed in solution by NMR measurements. It is proposed that facile AuRu bond rupture takes place to afford an intermediate with a square pyramidal Au2Ru3 core, as found in [Au2Ru3(μ-H)μ3-COMe)(CO)9(PPh3)2].

Replacement of hydrido-ligands in triruthenium complexes by triphenylphosphinegold groups. Crystal structures of [AuRu3(µ-COMe)(CO)10(PPh3)], [AuRu3(µ-H)2(µ3-COMe)(CO)9(PPh3)], and [Au3Ru3(µ3-COMe)(CO)9(PPh3)3]

The compound [AuMe(PPh3)] reacts under mild conditions (diethyl ether, ambient temperatures) with the compounds [M3(µ-H)(µ-COMe)(CO)10] and [Ru3(µ-H)3(µ3-COMe)(CO)9] to give the complexes [AuM3(µ-COMe)(CO)10(PPh3)][M = Fe (1) or Ru (2)], [AuRu3(µ-H)2(µ3-COMe)(CO)9(PPh3)](3), [Au2Ru3(µ-H)(µ3-COMe)(CO)9(PPh3)2](4), and [Au3Ru3(µ3-COMe)(CO)9(PPh3)3](5). Spectroscopic properties of the new species are reported and discussed, and the structures of (2), (3), and (5) have been established by X-ray diffraction studies. The structure of [AuRu3(µ-COMe)(CO)10(PPh3)](2) can be regarded as a molecule of [Ru3(µ-H)(µ-COMe)(CO)10] in which the bridging hydrido-ligand is replaced by a bridging AuPPh3 group, thus producing a ‘butterfly’ metal atom core (interplanar angle 117°) with the gold atom occupying a ‘wing-tip’ site. The COMe ligand bridges the body of the butterfly on the convex side. The Au–Ru bonds [2.760(2) and 2.762(2)A] are ca. 0.1 A shorter than the non-bridged Ru–Ru bonds [2.845(2) and 2.839(3)A] but the bridged Ru–Ru bond is significantly longer at 2.879(2)A. Crystals of (2) are triclinic, space group P, and the asymmetric unit comprises two molecules of complex. The structure has been refined to R 0.075 for 4 868 intensities measured to 20 = 40° at 220 K. In [AuRu3(µ-H)2(µ3-COMe)(CO)9(PPh3)](3) the carbyne ligand triply bridges an equilateral triangle [Ru–Ru 2.865(2)–2.879(2)A] of ruthenium atoms, while on the opposite side of the triangle there are two edge-bridging hydrido-ligands and one edge-bridging AuPPh3 group. Each ruthenium atom carries three terminal carbonyl ligands, giving octahedral co-ordination if the Ru–Ru bonds are ignored. The molecule has approximate Cs symmetry, not required crystallographically. The structure is triclinic, space group P, and has been refined to R 0.042 for 3 247 intensities measured to 2θ= 45° at 293 K. The complex [Au3Ru3(µ3-COMe)(CO)9(PPh3)3](5) crystallises with half a molecule of CH2Cl2 per molecule of (5) incorporated into the crystals. Again the carbyne ligand triply bridges a near-equilateral triangle of Ru atoms [Ru–Ru 2.895(3)–2.929(2)A], but on the opposite side of this triangle one gold atom is co-ordinated to form a tetrahedron [Au–Ru 2.818(2), 2.825(2), and 2.987(2)A]. The two faces of this tetrahedron adjacent to the long Au–Ru bond are each further triply bridged by AuPPh3 ligands. The two Au–Au distances in this bicapped tetrahedral structure are 2.930(1) and 3.010(1)A; the difference between these probably arises from the packing of the bulky triphenylphosphine ligands. Crystals of (5) are monoclinic, space group P21/n, and the structure has been refined to R 0.050 for 4 279 intensities measured to 2θ= 45° at 293 K.

Heteronuclear metal complexes with bridging methoxymetylidyne ligands: X-ray crystal structures of [AuRu3(µ2-COMe)(CO)10(PPh3)] and [Fe3Pt(µ3-H)(µ3-COMe)(CO)10(PPh3)]

Heteronuclear cluster compounds can be prepared from reactions between [M3(µ-H)(µ-COMe)(CO)10](M = Fe or Ru) and [ AuMePPh3], or between the tri-iron compound and [Pt(C2H4)2(PPh3)]; the structures of [AuRu3(µ2-COMe)(CO)10(PPh3)] and [Fe3Pt(µ3-H)(µ3-COMe)(CO)10(PPh3)] have been established by X-ray diffraction.

The heteronuclear cluster chemistry of the Group 1B metals. Part 1. Structural similarities and differences among mixed-metal cluster compounds containing copper, silver, or gold atoms ligated by phosphines. X-Ray crystal structures of [CuRu4(µ3-H)3(CO)12(PMePh2)] and [CuRu3(CO)9(C2But)(PPh3)]

Treatment of dichloromethane solutions of [N(PPh3)2][Ru4(µ-H)3(CO)12] or [N(PPh3)2][Ru3(CO)9(C2But)] with [M(NCMe)4]PF6(M = Cu or Ag) at –30 °C, followed by the addition of the desired phosphine ligand, affords the mixed-metal clusters [MRu4(µ3-H)3(CO)12L][M = Cu, L = PMePh2(1) or PPh3(2); M = Ag, L = PPh3(3)], [{MRu4(µ3-H)3(CO)12}2(µ-Ph2PCH2CH2PPh2)][M = Cu (6) or Ag (7)], and [MRu3(CO)9(C2But)(PPh3)][M = Cu (10) or Ag (11)] in ca. 70–80% yield. In dichloromethane solution, [N(PPh3)2][Ru4(µ-H)3(CO)12], [N(PPh3)2][Ru3(CO)9(C2But)], and [N(PPh3)2][Fe3(µ-COMe)(CO)10] also react directly with [MX(PPh3)](M = Cu or Au, X = Cl; M = Ag, X = I) or [Au2(µ-Ph2PCH2PPh2)Cl2], in the presence of TIPF6, to give reduced yields of (2), (3), (10), and (11), two analogous gold–ruthenium clusters [AuRu4(µ-H)3(CO)12(PPh3)](8) and [{AuRu4(µ-H)3(CO)12}2(µ-Ph2PCH2PPh2)](9), and the series of clusters [MFe3(µ-COMe)(CO)10(PPh3)][M = Cu (15), Ag (16), or Au (17)], as appropriate. All of these clusters have been characterized by i.r. and n.m.r. spectroscopy and the structures of (1) and (10) have been established by single-crystal X-ray diffraction studies. Clusters (8) and (9) adopt different metal-core structures to those of (1)–(3), (6), and (7), with the Au(PR3)(R = alkyl or aryl) fragment(s) in (8) and (9) bridging an edge of a ruthenium tetrahedron, whereas the M(PR3)(M = Cu or Ag) unit(s) in (1)–(3), (6), and (7) cap a face of a similar basic Ru4 tetrahedron. However, clusters (15), (16), and (17) all have the same skeletal geometry, with the M(PPh3)(M = Cu, Ag, or Au) groups bridging an edge of an iron triangle, and species (10) and (11) show the same ‘butterfly’ metal-core arrangement as that previously established for the analogous gold species [AuRu3(CO)9(C2But)(PPh3)]. The pentanuclear cluster [CuRu4(µ3-H)3(CO)12(PMePh2)](1) has a trigonal-bipyramidal metal-core geometry, with the copper atom occupying an apical site [Cu–Ru 2.717(1)–2.749(1), Ru–Ru 2.788(1)–2.970(1)A]. Each ruthenium atom is ligated by three terminal CO groups and the copper atom by the PMePh2 ligand. All three CuRu2 faces of the metal skeleton are capped by triply-bridging hydrido ligands [mean Cu–H 1.93(6), mean Ru–H 1.81(6)A]. The tetranuclear cluster [CuRu3(CO)9(C2But)(PPh3)](10) adopts a ‘butterfly’ metal-core structure (interplanar angle 115.7°), with the copper atom occupying a ‘wing-tip’ site. The two Cu–Ru bond lengths are equal [2.603(1)A] and the side of the Ru3 triangle which is bridged by the Cu(PPh3) fragment [2.762(1)A] is significantly shorter than the other two Ru–Ru distances [2.819(1) and 2.808(1)A]. The t-butylacetylide ligand lies on the convex side of the ‘butterfly’ metal core, interacting with all three ruthenium atoms via one σ bond to the ‘wing-tip’ ruthenium site and two π bonds to the two ruthenium atoms which form the ‘body’ of the ‘butterfly’. Each ruthenium atom is ligated by three CO groups, two of which also exhibit short Cu–C contacts [2.496(7) and 2.552(7)A].

The heteronuclear cluster chemistry of the group 1B metals. Part 4. Synthesis, structures, and dynamic behaviour of group 1B metal–ruthenium cluster compounds containing sulphur ligands. X-Ray crystal structures of [M2Ru3(µ3-S)(µ-Ph2PCH2PPh2)(CO)9](M = Cu or Au)

Treatment of a tetrahydrofuran solution of the salt K2[Ru3(µ3-S)(CO)9] with the complex [MX(PPh3)](M =Cu or Au, X =Cl; M = Ag, X = I), in the presence of TIPF6, affords a mixture of cluster compounds, [MRu3(µ-H)(µ3-S)(CO)9(PPh3)][for M = Cu (2), Ag (3), or Au (4)], [MRu3(µ-H)-(µ3-S)(CO)8(PPh3)2][for M = Cu (5) or Ag (6)], and [M2Ru3(µ3-S)(CO)9(PPh3)2][for M = Cu (8), Ag (9), or Au (10)]. In addition, the pentanuclear clusters [M2Ru3(µ3-S)(µ-Ph2PCH2PPh2)-(CO)9][M = Cu (12) or Au (13)] can be synthesized from the reaction between K2[Ru3(µ3-S)-(CO)9] and [M2(µ-Ph2PCH2PPh2)Cl2], using TIPF6. Infrared and n.m.r. spectroscopic data imply that the tetranuclear copper- or silver-containing species (2), (3), (5), and (6) all adopt the same ‘butterfly’ MRu3 metal-core geometry as that previously established for the Au cluster (4) and that the pentanuclear Cu and Ag species (8) and (9) exhibit the same trigonal-bipyramidal M2Ru3 framework as that determined for the Au cluster (10). However, X-ray diffraction studies on the bidentate phosphine-containing pentanuclear Cu2Ru3 species (12) and its Au2Ru3 analogue (13) reveal two different metal-corestructures. The Cu cluster (12) has a trigonal-bipyramidal metal skeleton [Cu–Cu 2.515(3), Cu–Ru 2.552(2)–2.794(2), Ru–Ru 2.814(2)–2.856(2)A], with one of the two phosphine-bridged Cu atoms occupying an equatorial site and the other an axial site. The S atom caps the Ru3 face of the trigonal-bipyramidal unit. In the Au species (13), the metal framework structure is intermediate between a trigonal bipyramid and a square-based pyramid [Au–Au 2.802(1), Au–Ru 2.742(l)–2.836(1), Ru–Ru 2.773(2)–2.968(2)A]. Variable-temperature n.m.r. studies show that, at ambient temperature in solution, the coinage metals in each of the pentanuclear clusters (8)–(10), (12), and (13) are exchanging between the two distinct sites in the cluster skeleton, the PPh3 groups in the copper–ruthenium species (2) and the silver–ruthenium species (3), (6), and (9) are undergoing intermolecular exchange between clusters, and the CO ligands in all of the clusters exhibit dynamic behaviour involving intramolecular site-exchange.

Hydrido-bridged bimetallic complexes involving gold or silver and chromium, molybdenum, or tungsten: X-ray crystal structure of [AuCr(µ-H)(CO)5(PPh3)]

Treatment of tetrahydrofuran solutions of the salts [N(PPh3)2][MH(CO)4L][M = Cr or W, L = CO; M = W, L = P(OMe)3] with [AuCl(PPh3)] in the presence of TIPF6 afforded the compounds [AuM(µ-H)(CO)4L(PPh3)]. The gold–molybdenum compound [AuMo(µ-H)(CO)5(PPh3)] was similarly prepared from a dichloromethane solution of [N(PPh3)2][Mo2(µ-H)(CO)10]. Reactions between [N(PPh3)2][MH(CO)4L][M = Cr or W, L = CO; M = W, L = P(OMe)3], [Agl(PMe3)], and TIPF6 yielded the hydrido-bridged bimetal compounds [AgM(µ-H)(CO)4L(PMe3)]. A single-crystal X-ray diffraction study has been carried out on the complex [AuCr(µ-H)(CO)5(PPh3)]. The molecule has a bent Au(µ-H) Cr geometry [Au–Cr 2.770(2), Au–H 1.72(11), and Cr–H 1.64(12)A; Au–H–Cr 111 (5)°] in accord with the presence of a three-centre two-electron bond. The orientation of the Cr(CO)5 group is staggered relative to the Au(µ-H)Cr bridge, with the hydrido-ligand lying transoid to the axial carbonyl ligand and the phosphine group. Crystals are triclinic, space group P(no. 2), and the structure has been refined to R 0.047 for 3 401 intensities measured at 210 K in the range 4 ⩽ 2θ⩽ 50°. Proton, 31P-{1H}, and 13C-{H} n.m.r. spectroscopic data for the various compounds are reported and show that these species undergo dynamic behaviour in solution involving dissociation of the PPh3 or PMe3 groups, site exchange of CO ligands, and, for the silver-containing complexes, dissociation of the MH(CO)4L fragments.

The heteronuclear cluster chemistry of the group 1B metals. Part 9. Stereochemical non-rigidity of the metal skeletons of cluster compounds in solution. 109Ag-{1H} INEPT nuclear magnetic resonance studies on [Ag2Ru4(µ3-H)2{µ-Ph2P(CH2)nPPh2}(CO)12](n= 1, 2, or 4) and X-ray crystal structure of [Ag2Ru4(µ3-H)2(µ-Ph2PCH2PPh2)(CO)12]

A combination of spectroscopic data and an X-ray diffraction study on [Ag2Ru4(µ3-H)2(µ-Ph2PCH2PPh2)(CO)12][Ag–Ag 2.756(6), Ag–Ru 2.820(6)–3.151(6), Ru–Ru 2.775(7)—2.998(6)A] shows that the clusters [Ag2Ru4(µ3-H)2{µ-Ph2P(CH2)nPPh2}(CO)12](n= 1–6) all adopt a capped trigonal-bipyramidal metal core geometry. However, although there are two distinct silver sites in the ground-state structures, ambient temperature 109Ag-{1H} INEPT n.m.r. spectra of the clusters in which n= 1, 2, or 4 show a single averaged silver resonance in each case. These studies provide the first direct evidence for stereochemical non-rigidity of the metal skeletons of Group 1B metal heteronuclear clusters in solution. In addition, values of 1J(107,109Ag107,109Ag) have been measured for the first time. The results of 31P-{109Ag} and 109Ag INEPT and DEPT n.m.r. studies on [AgRu4(µ3-H)3(CO)12(PPh3)] are also reported.

Cluster complex metathesis: synthesis, structures, and dynamic behaviour of Bi- and tri-metallic hexanuclear cluster complexes [MM′Ru4(µ3-H)2(CO)12(PPh3)2](M = M′= Cu, Ag, or Au; M = Cu, M′= Ag or Au; M = Ag, M′= Au)

The hexanuclear metal clusters [MM′Ru4(µ3-H)2(CO)12(PPh3)2](M = M′= Cu, Ag, or Au; M = Cu, M′= Ag or Au; M = Ag, M′= Au) have been prepared by treating the dianion [Ru4(µ-H)2(CO)12]2– with the complexes [MX(PPh3)](M = Au or Cu, X = Cl; M = Ag, X = l) in the presence of TIPF6; the trimetallic clusters may alternatively be synthesized by metathesis of the two appropriate bimetallic species, and the crystal structure of the compounds with the metal cores Cu2Ru4, Ag2Ru4, and CuAgRu4 have been established by X-ray diffraction.

Structural similarities and differences among mixed-metal clusters containing a single M(PPh3) (M = Cu, Ag or Au) fragment

Abstract The heteronuclear metal clusters [H3MRu4(CO)12(PPh3)] and [MFe3(μ-COMe)(CO)10(PPh3)] (M = Cu, Ag or Au) have been prepared; the gold-tetraruthenium cluster has a different metal core geometry to that adopted by the copper and silver analogues, whereas all three iron-Group IB mixed-metal clusters have the same geometry.

Cleavage of MC (M = Mo or W) bonds in the formation of the complexes [Fe2M(µ-C2R)(CO)8(η-C5H5)]: X-ray crystal structure of [Fe2W(µ-C2C6H4Me-4)(CO)8(η-C5H5)]

The compounds [M(CR)(CO)2(η-C5H5)](M = Mo, R Me; M = W, R = Me or C6H4Me-4) react with [Et3NH][Fe3(µ-H)(CO)11] in tetrahydrofuran at 80 °C to afford bridged-acetylide complexes [Fe2M(µ-C2R)-(CO)8(η-C5H5)]; the structure of the species M = W and R = C6H4Me-4 has been established by X-ray diffraction.