[4-{(p-cym)Ru}-5-{(Ph3P)(2)(CO)Os}B4H8]: the first nido-heterobimetallahexaborane cluster

The cluster nido-[4-{(p-cym)Ru}-5-{(Ph3P)(2)(CO)Os}B4H8] (1), where p-cym = [1-Me-4-(PrC6H4)-Pr-i], has been prepared as a pale yellow, air-sensitive solid from the reaction of [(p-cym)RuCl2](2), with Li[(PPh3)(2)(CO)OsB5H8]. The species was characterized by multinuclear NMP spectroscopy and high re solution mass spectrometry. The spectral data suggest a structure in which the two metal moieties are adjacent to each other in the basal region of a nido-hexaborane cluster. The pentagonal open face, B3RuOs, contains four br idging H atoms comprising two B-H-B and two metal-H-B bridge bonds. Attempt s to prepare the related Os2B4 and Ru2B4 clusters are also described as are observations on the degradation of these bimetallahexaboranes compared to their single metal-containing congeners, the osma- and ruthenahexaboranes. (C) 1999 Elsevier Science S.A. All rights reserved.