Macropolyhedral boron-containing cluster chemistry. Isolation and characterisation of the eighteen-vertex nido-5′-iridaoctaborano[3′,8′ : 1′,2]-closo-4-iridadodecaborane, [(CO)(PMe3)2IrB16H14Ir(CO)(PMe3)2]

Abstract

The novel eighteen-vertex macropolyhedral diiridaborane [(CO)(PMe₃)₂IrB₁₆H₁₄Ir(CO)(PMe₃)₂] has been isolated in low yield from the products of thermolysis of the nine-vertex arachno-monoiridaborane [(CO)(PMe₃)₂HIrB₈H₁₂], and examined by single-crystal X-ray diffraction analysis, NMR spectroscopy and mass spectrometry. The macropolyhedral framework consists of a closo-type twelve-vetex {IrB₁₁} subcluster and a nido-type eight-vertex {IrB₇} subcluster fused with two boron atoms in common. In addition there is an iridium–boron two-electron two-centre intercluster cross-linkage that is suprafacial to the open nido subcluster. The results are briefly discussed in terms of bonding schemes among individual subclusters.