Gold complexes hydrides

Gold(III) also forms complex hydrides with LiAlH and LiBH, stable only at low T. Analyses of the precipitated solids lead to such compositions as Al Au Hj, of unknown structure. ... 

The catalytic activity of the gold complex, AuCl(PPh3), is similar to that of the palladium complexes, and, for example, it reacts with trioctyltin hydride at room temperature in 13 h to give hexaoctyldistannane in 94% yield.29 A number of other transition metals are catalytically active, and these are listed in Chapter 15. 

Gold complexes of Cp-related ligands have also been prepared. 9-Fluorenyl (tri-phenylphosphine)gold(I) (2)131 can be obtained via the oxonium salt route, but the reduced C—H acidity of fluorene requires the use of an additional base, such as sodium hydride, to deprotonate the hydrocarbon. 

In addition to these catalytic applications of this interesting compound, Nolan and coworkers were able to synthesize a large array of other interesting gold complexes by starting from [Au(IPr)(OH)]. In particular, the easy access to a gold(I) hydride, which previously had been prepared by Tsui et al. [28], has to be noted (see Scheme 9.11). 

Gold-activated allene can also be employed as hydride acceptor. Gagosz et al. demonstrated that a phosphite gold complex 154-catalyzed intramolecular hydroalkylation of allenes 151, which afforded the spiro compound 152 and undesired fused bicyclic compound 153 in 30 and 61 % yields, respectively (Scheme 56) [128]. The selectivity could be reversed if HNTfa was exploited. 

Usui, Y, Hrrano, M., Fukuoka, A. and Komiya, S. (1997) Hydrogen abstraction from transition metal hydrides by gold alkoxides giving gold-containing heterodinuclear complexes. Chemistry Letters, 26, 981. 

The reaction of these complexes with metal hydrides of the type [CoF1(CO)4], [MnFl(CO)3], [MoFlCp(CO)3], [WHCp(CO)3], or [WFlCp(CO)2(PMe3)l progresses with the liberation of alcohol, ethane, and the corresponding gold(I) derivatives/ 87... 

A number of transition metal complexes will catalyze the dehydrogenative coupling of organotin tin hydrides, R SnI I, to give the distannanes, RjSnSnRj.443 These metals include palladium,449 gold,450, hafnium,451 yttrium, and ruthenium.452 The catalyst that is most commonly used is palladium, often as Pd(PPh3>4, and the most active catalysts appear to be the heterobimetallic Fe/Pd complexes, in which both metals are believed to be involved in the catalysis.443... 

Considerable inter-element interference effects have been reported on the actual hydride-forming step. Elements easily reduced by sodium borohydride (e.g. silver, gold, copper, nickel) give rise to the greatest suppressions. These interfering ions may be removed by the addition of masking agents that complex with them. 

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. 

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