Polyhedral metallathiaborane chemistry: Synthesis and characterisation of metallathiaboranes based on the twelve-vertex icosahedral closo-{MSB10H10} unit, where M is Rh or Ir

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