METALLAHETEROBORANE CHEMISTRY - PART 14 - SYNTHESIS OF THE (MS2B7)-CLUSTER COMPOUNDS [9,9-(PX3)(2)-9,6,8-PTS2B7H7] (WHERE X=PH OR OME), [9,9-(PPH3)(2)-9,6,8-RHS2B7H8] AND [5,5-(PPH3)(2)-5,6,10-RHS2B7H8], AND THE (M2S2B7)-CLUSTER COMPOUND [(PPH3)(2)HRH(PPH3)CLRHS2B7H7]

The ten-vertex {MS2B7} cluster compounds [9,9-(PPh3)(2)-9,6,8-PtS2B7H7 ] la, [9,9-{P(OMe)(3)}(2)-9,6,8-PtS2B7H7] Ic, and [9,9-(PPh3)(2)-9,6,8 -RhS2B7H8] 2 were synthesised in reactions between arachno-4,6-S2B7H9 and the metal phosphine complexes [Pt(PPh3)(4)], [PtCl2{P(OMe)(3)}(2)] and [RhCl(PPh3)(3)], respectively. Heating a solution of [9,9-(PPh3)( 2)-9,6,8-RhS2B7H8] in benzene afforded its isomer [5,5-(PPh3)(2)-5,6,1 0-RhS2B7H8] 3. The eleven-vertex {M2S2B7} cluster compound, [(PPh3)(2) HRh(PPh3)ClRhS2B7H7] 4 was synthesised in the reaction between S2B7H9 and [RhCl(PPh3)(3)] in 1:2 molar ratio, and exhibits a novel cluster s tructure with the metal and sulphur atoms assembled in a sequential M- S-M-S manner on the borane sub-cluster matrix. All compounds 1 to 4 we re characterised by spectroscopic methods and, in the cases of la and 4, by single-crystal X-ray diffraction analysis. These observations ar e discussed in the light of the electronic and structural requirements of the metal units involved in metallathiaborane cluster compounds. ( C) 1998 Elsevier Science S.A.