Polyhedral metallathiaborane chemistry: Synthesis and characterisation of metallathiaboranes based on the twelve-vertex icosahedral closo-{MSB 10H 10} unit, where M is Rh or Ir

Abstract

The reaction of [ nido-7-SB 10H 12] with [RhCl(PPh 3) 3] in the presence of N, N, N′ N′-tetramethylnaphthalene-1,8-diamine (tmnd) in CH 2Cl 2 gives twelve-vertex [2,2-(PPh 3) 2-2-H- closo-2,1-RhSB 10H 10] ( 1) and eleven-vertex [8,8-(PPh 3) 2- nido-8,7-RhSB 9H 10] ( 2), as major products, plus the dimeric species [{(PPh 3)- closo-RhSB 10H 10} 2] ( 3) as a minor product. Reaction of 1 with PMe 2Ph in CH 2Cl 2 results in phosphine exchange and hydride substitution, affording the chloro analogue of 1, [2,2-(PMe 2Ph) 2-2-Cl- closo-2,1-RhSB 10H 10] ( 4). By contrast, reaction between [IrCl(PPh 3) 3] and [ nido-7-SB 10H 12] in CH 2Cl 2 with tmnd affords only one product, twelve-vertex [2,2-(PPh 3) 2-2-H- closo-2,1-IrSB 10H 10] ( 5). [RhCl 2(η 5-C 5Me 5)] 2 with [ nido-7-SB 10H 12] under the same conditions gives twelve-vertex [2-(η 5-C 5Me 5)- closo-2,1-RhSB 10H 10] ( 6). All the compounds are characterised by NMR spectroscopy, and by mass spectrometry, and the molecular structure of [2,2-(PMe 2Ph) 2-2-Cl- closo-2,1-RhSB 10H 10] ( 4) was established by single-crystal X-ray diffraction analysis. This last rhodathiaborane 4 is fluxional in solution through a process that involves a reversible partial rotation of the {RhCl(PMe 2Ph) 2} unit above the {SB 4} pentagonal face of the {SB 10H 10} fragment.