Ten-vertex metallaborane chemistry: facile, thermally induced, nido→isocloso cluster-closure oxidation reactions in iridadecaborane clusters

Abstract

Four nido-iridadecaborane cluster compounds [6-H-6,6-(PR₃)₂-nido-6-IrB₉H₁₃][R = Ph, (1); Me, (5)][sym-6-H-6-(PPh₃)-6-(PPh₂-ortho-[graphic omitted]](2), and [5-H-5-(PPh₃)-5-(PPh₂-ortho-[graphic omitted]](3) lose hydrogen on heating in dichloroethane solution at ca. 80 °C (bath) to give, in each case, an ‘isocloso’ iridadecaborane cluster compound. These isocloso species have been characterised by multielement n.m.r. studies and, in the case of [1-H-1-(PPh₃)-1-(PPh₂-ortho-[graphic omitted]](4), by a single-crystal X-ray crystallographic study. Crystals of (4) are monoclinic, space group P2₁/c with a= 1366.0(3), b= 1906(4), c= 1429.1(3) pm, β= 103.71(2)°, and Z= 4. The ‘isocloso’ structures and a possible mechanism for the nido→isocloso cluster closure are briefly discussed.