SYNTHESIS, STRUCTURE AND REACTIVITY OF A NOVEL MONOCARBON HYDRIDORHODACARBORANE CLOSO-2,2-(PH3P)(2)-2-H-1-(ME3N)-2,1-RHCB10H10 - MOLECULAR-STRUCTURE OF 16-ELECTRON CLOSO-2-(PH3P)-2-CL-1-(ME3N)-2,1-RHCB10H10 AND CLOSELY-RELATED 18-ELECTRON CLOSO-3,3-(PH3P)(2)-3-CL-3,1,2-RHC2B9H11

A novel 12-vertex monocarbon hydridorhodacarborane closo-2,2-(Ph3P)(2) -2-H-1-(Me3N)-2,1-RhCB10H10 1 has been synthesized by the reaction of Rh(PPh3)(3)Cl (2) with nido-B10H12CNMe3 (3) under alkaline conditions. At low temperature 1 exists as a mixture of two preferred conformers in solution, both having C-s symmetry, in accord with the hindered rot ation of the (Ph3P)(2)RhH vertex with respect to the CB, face of the m onocarbon carborane cage. Complex 1 readily reacts with chlorine-conta ining reagents to form mononuclear 16-electron closo-2-(Ph3P)-2-Cl-1-( Me3N)-2,1-RhCB(10)H(1)0 (5), whose structure was unambiguously confirm ed by an X-ray diffraction study. The results of an X-ray diffraction study of the closely related dicarbon carborane derivative closo-3,3-( Ph3P)(2)-3-Cl-3,1,2-RhC2B9H11 (10), prepared from closo-3,3-(Ph3P)(2)- 3-H-3,1,2-RhC2B9H11 by analogy with 5, are also reported. (C) 1997 Els evier Science S.A.