Cluster gold hydride

U. Kaldor and B. A. Hess, Ghent. Phys. Lett., 230, 1 (1994). Relativistic All-Electron Coupled-Cluster Calculations on the Gold Atom and Gold Hydride in the Framework of the Douglas-Kroll Transformation. 

Kaldor, U., Hess, B.A. Relativistic all-electron coupled-cluster calculations on the gold atom and gold hydride in the framework of the Douglas-Kroll transformation. Chem. Phys. Lett. 230, 1-7 (1994)... 

The synthetic methods used involve reaction of a cluster anion with [AuCIL], elimination of methane between a cluster hydride and [AuMeL] or addition of LAu+ units to metal-metal bonds. The emphasis here will be on structure and reactions of the complexes. Some examples of mixed gold clusters are given in Table 15, where it can be seen that most work has been on derivatives of clusters of iron, ruthenium and osmium. 

Finally, hydride for methyl group exchange may have been involved (2/6) in a reaction with/ran.s-[PtIH(PMe3)2] [Eq. (67)]. The hydridogold(I) species, if that was indeed the product obtained, underwent further reaction to yield a probable gold cluster compound. 

Fast atom bombardment mass spectroscopy has proved to be most useful when applied to the characterization of heteronuclear gold cluster compounds containing hydride ligands (137,149,155). Characterization is aided by the observation that peaks are invariably present in the spectrum corresponding to ions that contain all of the hydride... 

H NMR spectroscopy has been used extensively in the characterization of gold heteronuclear cluster compounds that possess hydride ligands. For example, Fig. 12 illustrates the hydride region of the H NMR spectrum of [Au4Rh(H)2 P(0-i-C3H7)3 2(PPh3)4]+ (155). 

Spectroscopic studies have again indicated the presence of four hydride ligands in both clusters and although these could not be positioned with certainty they most probably bridge between the rhenium and gold atoms. In both clusters, the Au-Re bond lengths are considerably shorter than the Au-Au bond lengths (see Table X). 

The highly reduced M(CO)3" is stable only at low temperature and explodes upon warming especially when dry. It can undergo monoprotonation and stannyla-tion to form [HTa(CO)5]2" and [Ph3SnTa(CO)5]2" anions, respectively. The hydride is a useful precursor to [(Ph3PAu)3Ta(CO)5], which is the only known gold cluster of tantalum. 

Molecular binding of H2 to solid materials and catalysts such as metal surfaces and small metal clusters is rare since formation of metal hydrides is favored. H2 is observed by electron energy loss spectroscopy (EELS) to bind to a stepped Ni(510) surface containing unsaturated sites but not on the flat Ni(lOO) surface that lacks the requisite residual unfilled d states.Undoubtedly, such H2 binding is the first step in H2 dissociation on many other surfaces that form hydrides, for example, as similarly shown forNi(lll), Ni(lOO), Ni(llO), and Pd(210). H2 also ligates in small clusters such as Cu3(H2) in Ar matrices,and H2 binds to similar species for M = Fe, Co, Ni, Pd at low temperature. Monometallic species of these types have been studied by Andrews for many transition metals, including gold. ... 

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