NEW SYNTHETIC ROUTES TO B-HALOGENATED DERIVATIVES OF COBALT DICARBOLLIDE

The synthesis and characterization of the B(10),B(10')-dihalogenated m etallocarboranes [Co(10-X-7,8-C2B9H10)(2)](-), where X = Cl or Br, are reported. The C-2h symmetry of these diamagnetic Co(III) compounds al lows straightforward identification using B-11 and B-11{H-1} NMR. The compound [(CH3)(4)N][Co(7,8-C2B9H11)(2)] reacts in acidic NaOCl/HCl(aq ) to form the dichlorinated derivative [(CH3)(4)N][Co(10-Cl-7,8-C2B9H1 0)(2)]. Reaction of [(CH3)(3)NH][Co(7,8-C2B9H11)(2)] with N-chlorosucc inimide or N-bromosuccinimide in THF affords the dihalogenated derivat ives [(CH3)(3)NH][Co(10-Cl-7,8-C2B9H10)(2)] and [(CH3)(3)NH][Co(10-Br- 7,8-C2B9H10)(2)], respectively. Reaction of [(CH3)(3)NH][Co(7,8-C2B9H1 1)(2)] with Cl-2/Fe or Br-2 in THF also gives the dihalogenated deriva tives [(CH3)3-NH] [Co(10-Cl,7,8-C2B9H10)(2)] and [(CH3)3NH][Co(10-Br,7 ,8-C2B9H10)(2)], respectively. [PPN][Co(10-Cl,7,8-C2B9H10)(2)] (PPN = bis(triphenylphosphine)nitrogen(1+)) crystallizes in the monoclinic sp ace group C2/c, with a = 31.267(5) Angstrom, b = 9.0190(10) Angstrom, c = 18.706(3) Angstrom, beta = 116.970(0)degrees, V = 4701.8(15) Angst rom(3), Z = 4, and R = = 0.054. The structure was determined by X-ray crystallography using 6830 independent reflections.