Some ten-vertex nido-metallaboranes : oxidative insertion of iridium(I) and rhodium(I) into the arachno-nonaborate anion, [B9H14]–, and the crystal and molecular structure of 6-hydrido-6,6-bis(triphenylphosphine)-nido-6-iridadecaborane, [(HIrIIIB9H13)(PPh3)2]

Abstract

The arachno-anion [B₉H₁₄]^– reacts with trans-[Ir(CO)CI(PPh₃)₂], trans-[Ir(CO)CI(PMe₃)₂], [{Ir(cod)CI}₂], and [{Rh(cod)CI}₂](cod = cyclo-octa-1,5-diene) to give low yields of the nido-6-metalladecaboranes [6-H-6,6-(PPh₃)₂-nido-6-lrB₉H₁₃], [6-H-6,6-(PMe₃)₂-nido-6-IrB₉H₁₃], [6-(η²:η²-cod)-6-Cl-nido-6-IrB₉H₁₃], and [6-(η²:η²-cod)-6-Cl-nido-6-RhB₉H₁₃] respectively. These products have been characterized by single- and multiple-resonance n.m.r. spectroscopy and by single-crystal X-ray diffraction analysis on [6-H-6,6-(PPh₃)₂-nido-6-IrB₉H₁₃]. This last compound crystallizes in the orthorhombic space group Pna2₁, with a = 1 942.7(4), b= 1 196.7(2), c= 1 552.2(3) pm, Z= 4, and the structure (R= 0.024 for 2 333 observed reflections) of the metallaborane unit is that of a ten-vertex nido-cluster similar to that of B₁₀H₁₄, with the metal atom in the 6-position in the open face. The geometry about the iridium(III) atom is essentially octahedral, the metal being incorporated in the cluster via a direct Ir–B(2) bond and two Ir–H–B bridge bonds which differ in that one is trans to Ir–H(terminal) and the other trans to Ir–P.