J. J. Bour

Heterometallic Pt-Au complexes with μ-3 S bridging. Syntheses and structures of Pt2 (PPh3)4(μ-SAuCl)2·2CH2Cl2 and Pt2(PPh3)4−(μ-S)(μ-SAuPPh3)NO3·0.5H2O

Abstract From Pt 2 (PPh 3 ) 4 (μ- S ) 2 ( I ) three heterometallic complexes can be prepared: Pt 2 (PPh 3 ) 4 (μ-SAuCl) 2 ( II ), (Pt 2 (PPh 3 ) 4 (μ-SAuPPh 3 ) 2 2+ ( III ) and Pt 2 (PPh 3 ) 4 - (μ-S)(μ-SAuPPh 3 ) + ( IV ). Their preparation and properties are described. The crystal and molecular structures of II and the nitrate of IV has been investigated by X-ray diffraction analysis. II crystallizes in the monoclinic space group P 2 1 / n , a = 18.359(2) b = 13.947(2), c = 14.588(2) A, β = 100.982(7)°, V = 3666.9 A 3 , M r = 2138.28, Z = 2, D c = 1.94 Mg/m 3 . Mo Kα radiation (graphite crystal monochromator, λ = 0.71069 A, μ(Mo Kλ)= 85.13 cm −1 , F (000) = 2032, T = 293 K. Final conventional R -factor = 0.039, Rw = 0.050 for 5084 unique reflections and 155 variables. IV crystallizes in the triclinic space group P 1 , a = 14.605(1), b = 15.989(2), c = 18.005(2) A, α = 101.144(8)°, β = 100.773(7)°, γ = 91.201(2)°, V = 4045.4 A 3 , M r = 2033.75, Z = 2, D c = 1.66 Mg/m 3 . Cu Kα radiation (graphite crystal monochromator, λ = 1.5418 A), μ(Cu Kα) = 116.45 cm −1 , F (000) = 1986, T = 293 K. Final conventional R -factor = 0.039 Rw = 0.051 for 8631 unique reflections and 297 variables. Both the structures were solved using SHELX84 and DIRDIF. The hinged square planar geometry of the parent I is kept in IV , where AuPPh 3 is bonded to one of the bridging S atoms. In II both bridging S atoms are bonded to AuCl and the hinging geometry is transformed into a nearly planar P 2 PtS 2 PtP 2 frame with the SAuCl vectors nearly perpendicular to it, one on each side of that plane. There are indications for weak AuPt bonding interactions. In IV and II the three-coordinated S-atoms have bond angles of about 90°. The structure of III is supported to be similar to II . Some reactions and interconversions of II , III and IV are described.

Reactions of gold–phosphine cluster compounds. Preparation and X-ray structure determination of octakis(triphenylphosphine)octa-gold bis(hexafluorophosphate)

[Au9L8]3+(L = PPh3) reacts with L to form [Au8L8]2+ and [AuL2]+; preliminary X-ray structural results are reported for [Au8L8][PF6]2.2CH2Cl2(1).

Preparation and X-ray structure determination of [pentakis{1,3-bis(diphenylphosphino)propane}] undecagoldtris(thiocyanate), [Au11{PPh2C3H6PPh2}5](SCN)3

The reaction of Au11[P(p-ClC6H4)3]7(SCN)3 with 1,3-bis(diphenylphosphino) propane (dppp) in methylene chloride leads to the formation of [Au11(dppp)5] (SCN)3 by a total substitution of the ligands. The compound crystallizes in the triclinic space groupP¯1,a=17.369,b=18.222,c=27.810 Å, α=104.00,β=105.25, γ=85.47°,Z=2. The structure was determined by a combination of Patterson, DIRDIF, and Fourier methods, with diffractometer data and refined by least-squares group refinement toR=0.081 for 2774 reflections.

Gold clusters: synthesis and characterization of [Au8(PPh3)7(CNR)]2+, [Au9(PPh36(CNR2]3+ and [Au11(PPH37(CNR)2O]2+ and their reactivity towards amines. The crystal structure of [Au11(PPh3)7(CN-i-Pr)2I](PF6)2

Abstract In the reactions of [Au8(PPh3)7]2+, [Au8(PPh3)8]2+ and [Au9(PPh3)8]3+ with RNC (R = isopropyl and t-butyl) in dichloromethane [Au8(PPh3)7CNR]2+ is initially, and is then converted into [Au9(PPh3)6(CNR)2]3+ via various intermediates. [Au9(PPh3)6(CNR)2]3+ reacts with I− at low temperature (−78°C) in methanol to yield [Au11(PPh3)7(CNR)2I]2+, but when the reaction is carried out at room temperature Au11 (PPh3)6(CNR)I3 is formed. The cluster compounds have been characterised by elemental analysis, 31P{1H} NMR, conductivity measurements, IR and 197Au Mossbauer spectroscopy. The reactions of the clusters with amines to form carbene clusters are very slow, and the reasons for this are considered. The structure of [Au11C134H112IN2P7](PF6 was determined by X-ray diffraction. Mr = 3796.39 cubic, space group 143d, a 37.955(12) A, V 54677.2 A3, Z = 16, Dc = 2.21 Mg m−3, Mo-Kα radiation (graphite crystal monochromator, λ 0.71069 A), μ(Mo-Kα) 125.2 cm−1, F(000) = 33510.3, T 293 K. Final conventional R-factor = 0.048, Rw = 0.062 ofr 1867 unique reflections and 198 variables. The Au-skeleton is the same as in Au11(PPh3)8I3 having C3v symmetry with one central and 10 peripheral Au atoms.

Synthesis and structural characterisation of [Pt3Au(μ2-CO)3(PPh3)5]NO3

The compound [Pt3Au(μ2-CO)3(PPh3)5]NO3 was formed as the main product of the reaction of AuPPh3NO3 with Pt(PPh3)3 and CO. Its structure was determined by X-ray diffraction, using Cu-Kα radiation with a graphite crystal monochromator; λ 1.54184 A, AuC93H75NO6P5Pt3 · 12 C4H10O, Mr = 2276.80, triclinic, space group P1−, a 15.256(2), b 14.422(2), c 21.663(3) A, α 93.138(9), β 91.823(9), γ 68.654(9)°, V 4432(3) A3, Z = 2, Dc 1.678 Mg/m3, μ(Cu-Kα) 131.8 cm−1, F(000) = 21.94, T 290 K. Final conventional R factor = 0.063, Rw = 0.078 for 11193 unique reflections and 322 variables. The structure was solved by automated Patterson methods. The metal cluster is a strongly distorted tetrahedron with one short (2.700(1) A) and two longer (2.906(1) A) PtAu distances. This bonding asymmetry is discussed in a comparison with known structures of similar 54 and 56 valence electron Pt3Au clusters.

Reactions of gold–phosphine cluster compounds

[Au9L8]3+(L = PPh3) reacts with L to give [Au9L10]3+ and with X–(X = Cl, Br, I, CN, or SCN) to give Au9L8X3 which converts into [Au11L8X2]+ in solution (investigated for X = Cl and SCN); from 31P [1H] n.m.r., i.r., and Mossbauer spectra it is concluded that these new Au9 and Au11 clusters are structurally related to the known complexes [Au9L8]3+ and Au11L7X3, respectively.

Synthesis and characterization of [Pt(CN)(AuCN)(AuPPh3)8](NO3) and Pt(CO)(AuPPh3)6(AuCN)2. Crystal structure of [Pt(CN)(AuCN)(AuPPh3)8] (NO3)

Abstract Pt(CN)(AuCN)(AuPPh3)8+ (1) can be prepared from Pt(AuPPh3)82+ (2) by an oxidative addition reaction with Au(CN)2−. The CO in Pt(CO)(Au- PPh3)82+ cannot be replaced with CN−, but in a slow process two PPh3 are replaced, forming Pt(CO)(Au- CN)2(AuPPh3)6 (3). The compounds are characterized by 31P, 13C and 195Pt NMR, FAB-MS and IR measurements. The structure of Pt(CN)(AuCN)- (AuPPh3)8(NO3) is determined by X-ray diffraction (monoclinic, space group P21/n, a = 17.269(20), b = 29.638(17), c = 27.88(3) A, β = 93.95(14)°, V = 14233 A3, Z = 4, the residuals are R = 0.063 and Rw = 0.090 for 5965 observed reflections and 467 variables Cu Kα radiation). In the metal cluster the central Pt atom is surrounded by eight Au atoms and one CN ligand in a spheroidal structure similar to that of Pt(CO)(AgNO3)(AuPPh3)82+.

Synthesis of a new heteronuclear gold–cobalt cluster. Preparation and X-ray structure determination of tetrakis (triphenylphosphine)-bis(tetracarbonylcobalt)hexagold

The reaction of [AU8L7]2+(L = PPh3) with an excess of Li[Co(CO)4] in tetrahydrofuran results in the formation of Au6L4[Co(CO)4]2, the structure of which has been determined by X-ray crystallography.

Gold clusters. Reactivity of [Au9(PPh3)8]3+ and [Au8(PPh3)7]2+ towards isopropyl isocyanide

Abstract Isopropyl isocyanide reacts with [Au 9 (PPh 3 ) 8 ] 3+ or [Au 8 (PPh 3 ) 7 ] 2+ in CH 2 Cl 2 to give the cluster complex [Au 9 (PPh 3 ) 6 (i-PrNC) 2 ]X 3 (X = NO 3 or PF 6 ), in which the peripheral Au atoms are bonded to PPh 3 or i-PrNC. The complex has been characterized by elemental analysis, molecular weight, NMR, IR and Mossbauer spectroscopy.

Synthesis and X-ray crystal structure determination of the cationic gold cluster compound [Au8(PPh3)7](NO3)2

The reaction of [Au8L8](NO3)2(L = PPh3) with the phosphine scavenger [RhCl(C8H14)2]2 yields [Au8L7]-(NO3)2, X-ray analysis of which reveals the Au skeleton to be a fragment of the centred icosahedron; the cluster to be a fragment; the cluster is an intermediate in the reactions of [Au9L8]3+, and its 197 Au Mossbauer spectrum lacks, like that of [Au9L8]3+, a separate resonance for the central Au atom.