Polyhedral organoiridaborane chemistry. The reaction of MeNC with [6-(η5- C5Me5)-nido-6-IrB9H13]. Nuclear magnetic resonance studies and the crystal and molecular structure of [4,4-(η5-C5Me5)(MeNC)-arachno-4-IrB8H12]

Abstract

The reaction between MeNC and [6-(η⁵-C₅Me₅)-nido-6-IrB₉H₁₃] results in the formation of two new yellow air-stable arachno metallaboranes, the ten-vertex compound [6-(η⁵-C₅Me₅)-6-(endo-MeNC)-arachno-6-IrB₉H₁₁-9-(exo-MeNC)], and the nine-vertex compound [4-(η⁵-C₅Me₅)-4-(endo- MeNC)-arachno-4-IrB₈H₁₂]. Both new species are characterized by multielement and multiple resonance n.m.r. spectroscopy and the nine-vertex species also by single-crystal X-ray diffraction analysis. Crystals were monoclinic, space group P2₁/n, with a= 1 392.0(2), b= 1 010.6(2), c= 1 480.8(2) pm, β= 113.01(1)°, and Z= 4. The structure refined to R= 0.0210 R′= 0.0212. The endo-type hydrogen atoms on B(6) and B(8) were located and shown to have partial bridging character to B(7).