SYNTHESIS OF HETEROBIMETALLABORANES AND RELATED SPECIES FROM [(PPH(3))(2)(CO)OSB5H9] - PILEO-[(PPH(3))(2)(CO)OSB5H5IRH(PPH(3))(CO)],CLOSO-[(PPH(3))(2)(CO)(MU-H)OSB4H5(ETA(5)-(C(5)ME(5))M)] (M=RH, IR), NIDO-[(PPH(3))(2)(CO)OS(MU-H)(ETA(5)-(C(5)ME(5))IR)B3H6], AND NIDO-[(PPH(3))(2)(CO)OSB4H7(N-C4H9)]

A number of new heterobimetallaborane clusters have been synthesized from the addition of metal halide complexes to nido-[(PPh(3))(2)(CO)OsB5H8][Li]. The compounds have been characterized fully by NMR, IR, mass spectroscopy, and single-crystal X-ray diffraction techniques as pileo-[1,1,1-H(PPh(3))(CO)-2,2,2-(PPh(3))(2)(CO)-1,2-IrOsB5H5] (1), closo-[1-(C(5)Me(5))-2,2,2,-(CO)(PPh(3))(2)-1,2-(mu H)-1,2-IrOsB4H5] (2a), and nido-[2-(eta(5) C(5)Me(5))-3,3,3-(CO)(PPh(3))(2)-2,3(mu H)-2,3-IrOsB3H6] (3) A rhodium analogue of 2a was also prepared and characterized by NMR spectroscopy as closo-[1-(C(5)Me(5))-2,2,2,-(CO)(PPh(3))(2)-1,2-(mu H)-1,2-RhOsB4H6] (2b). The complexes all contain seven cluster skeletal electron pairs within 7, 6, and 5 cluster vertices, thus attaining an interesting pileo-closo-nido sequence of structures. The alkyl substituted nido-osmapentaborane cluster nido-[2,2,2-(PPh(3))(2)(CO)-2-OsB4H7(C4H9)] (6), identified by NMR, IR, and mass spectroscopy, is also described.