METALLABORANE REACTION CHEMISTRY .3. REACTION OF CARBON-MONOXIDE WITH6-(PPH3)-6(P),5(C)-MU-(2-PH2PC6H4)-NIDO-6-IRB9H12] AND THE ISOLATION AND CHARACTERIZATION OF 2 ARACHNO-6-MONOIRIDADECABORANES 3)(2)-6(P),5(C)-MU-(2-PH2PC6H4)-ARACHNO-6-IRB9H11] AND CO)-6-H-6,6-(PME2PH)(2)-9(PPH3)-ARACHNO-6-IRB9H11]

3)(2)-6(P),5(C)-mu-(2-Ph2PC6H4)-arachno-6-IrB9H11] (1) results from th e reaction of 6-(PPh3)-6(P),5(C)-mu-(2-Ph2PC6H4)-nido-6-IrB9H12] (2) w ith carbon monoxide in refluxing benzene. It is characterised by NMR s pectroscopy and by single-crystal X-ray diffraction analysis. Crystals were triclinic, space group <P(1)over bar>, with a = 10.688(2), b = 1 3.114(3), c = 22.356(5) Angstrom, alpha = 78.33(2), beta = 89.482(10), gamma = 70.884(12)degrees, and Z = 2. The compound is of the little-e xamined arachno ten-vertex metallaborane structural type. A second com pound of this type, O)-6-H-6,6-(PMe2Ph)(2)-9-(PPh3)-arachno-6-IrB9H11] (3), isolated from a reaction system involving [Ir(CO)Cl(PPh3)(2)], P Me2Ph and the [nido-B9H12](-) anion, has also been characterised cryst allographically. Crystals were triclinic, space group <P(1)over bar>, with a = 10.389(1), b = 10.511(1), c = 19.699(3) Angstrom, alpha = 75. 03(1), beta = 85.53(1), gamma = 74.88(1)degrees, and Z = 2.