Synthesis and characterisation of a series of Group 7 metal 2,2,2,2-dicarbonylbis(triorganophosphine)-arachno-2-metallatetraboranes, [M(CO)2L2(B3H8)] (M=Re, Mn);: crystal and molecular structures of [Re(CO)2(dppf)(B3H8)] and [Mn(CO)2(dppe)(B3H8)]

Arachno-2-metallatetraboranes, [M(CO)(2)L-2(B3H8)] (M = Re, L = PPh3, P(C6H4Cl-4)(3), P(C6H4OMe-4)(3), P(CH2Ph)(3); M = Mn and Re, L = 1/2dppm, 1/2dppp, 1/2dppb, 1/2dppf; M = Mn, L = 1/2dppe), have been synthesised from reactions of [NBu4][B3H8] with fac, cis-[MBr(CO)(3)L-2.] under photolytic conditions. These compounds were characterised by NMR (H-1, B-11, P-31) and IR spectroscopy. [Mn(CO)(2)(dppe)(B3H8)] and [Re(CO)(2)(dppf)(B3H8)] were further characterised by single-crystal X-ray diffraction studies. These studies confirmed molecular Cs symmetry and a trans dicarbonyl arrangement. Similar reactions with the bis(monodentate) organophosphine complexes, mer, trans-[MnBr(CO)(3)L-2], did not yield isolatable arachno-2-metallatetraboranes. (C) 2003 Elsevier Science Ltd. All rights reserved.