Carbonylmetalates have long been used for the synthesis of metal cluster complexes and have proved particularly useful in mixed-metal cluster chemistry. The HOMO of 18-electron reagents such as [CpMo(CO),]-(Cp = q-C5H5) has mostly metal d orbital character, accounting for its propensity to form metal-metal bonds. For the isosteric reagent [CpMn-(CO),(CN)]-, in contrast, the HOMO is centered on the cyano nitrogen atom, which explains the tendency of this anion to form linear Mn-CN-M' arrays."] In 1990 we found that this cyanometalate is simultaneously involved in both Mn-CN-Pd and direct Mn-Pd bonding in the unprecedented octanuclear, double-helix-type cluster 1 .[21 We have begun an investigation of the reactivity of electronically related borole-containing metalates such as 2, where the negative charge is very much delocalized, and 3, where it is mostly associated with the cyano ligWe also hoped that these compounds would allow the synthesis of the first cluster complexes containing a borole ligand. This was actually achieved and we present here our first results with anion 2 and the characterization of an unprecedented Re,Pd, cluster 4.

The first heterometallic borole complexes of Fe and Au have been prepared by reaction of [HFe{η5-(1-phenylborole)}(CO)2]- (1) with [AuCl(PPh3)] in CH2Cl2, and the crystal structure of [(OC)2{η5-(1-phenylborole)}Fe{Au(PPh3)}2] (2) reveals an interesting orientation of the borole ligand. This complex reacts with [AuCl(PPh3)]/TIPF6 in CH2Cl2 to give the new cationic FeAu3 cluster [(OC)2{η5-(1-phenylborole)}Fe{Au(PPh3)}3]PF6 (4) which has a tetrahedral metal core, as established by a wide angle X-ray scattering study.

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