Facile formation of exo-nido→closo-rearrangement products upon the replacement of PPh3 ligands with bis(diphenylphosphino)alkanes in “three-bridge” ruthenacarborane 5,6,10-[RuCl(PPh3)2]-5,6,10-(μ-H)3-10-H-exo-nido-7,8-C2B9H8

The replacement of the PPh₃ ligands in “three-bridge” exo-nido-ruthenacarborane 5,6,10-RuCl(PPh₃)₂]-5,6,10-(μ-H)₃-10-H-exo-nido-7,8-C₂B₉H₈ with diphosphines, viz., 1,3-bis(diphenylphosphino)propane (dppp) or 1,4-bis(diphenylphosphino)butane (dppb) dramatically decreases the barrier to the thermal exo-nido→closo rearrangement affording the chelate closo-complexes 3,3-Ph₂P(CH₂)_nPPh₂]-3-H-3-Cl-closo-3,1,2-RuC₂B₉H₁₁ (n = 3 or 4) under mild conditions. In the reaction with dppp, the rearrangement is accompanied by the formation of 17-electron paramagnetic closo-ruthenacarborane 3,3-Ph₂P(CH₂)₃PPh₂]-3-Cl-closo-3,1,2-RuC₂B₉H₁₁, which could be isolated as the main product when the reaction was carried out at 80 °C. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2455–2459, November, 2005.