New synthetic routes to B-halogenated derivatives of cobalt dicarbollide

The synthesis and characterization of the B(10),B(10{prime})-dihalogenated metallocarboranes [Co(10-X-7,8-C{sub 2}B{sub 9}H{sub 10}){sub 2}]{sup {minus}}, where X = Cl or Br, are reported. The C{sub 2h} symmetry of these diamagnetic Co(III) compounds allows straightforward identification using {sup 11}B and {sup 11}B({sup 1}H) NMR. The compound [(CH{sub 3}){sub 4}N][Co(7,8-C{sub 2}B{sub 9}H{sub 11}){sub 2}] reacts in acidic NaOCl/HCl(aq) to form the dichlorinated derivative [(CH{sub 3}){sub 4}N][Co(10-Cl-7,8-C{sub 2}B{sub 9}H{sub 10}){sub 2}]. Reaction of [(CH{sub 3}){sub 3}NH][Co(7,8-C{sub 2}B{sub 9}H{sub 11}){sub 2}] with N-chlorosuccinimide or N-bromosuccinimide in THF affords the dihalogenated derivatives [(CH{sub 3}){sub 3}NH][Co(10-Cl-7,8-C{sub 2}B{sub 9}H{sub 10}){sub 2}] and [(CH{sub 3}){sub 3}NH][Co(10-Br-7,8-C{sub 2}B{sub 9}H{sub 10}){sub 2}], respectively. Reaction of [(CH{sub 3}){sub 3}NH][Co(7,8-C{sub 2}B{sub 9}H{sub 11}){sub 2}] with Cl{sub 2}/Fe or Br{sub 2} in THF also gives the dihalogenated derivatives [(CH{sub 3}){sub 3}-NH][Co(10-Cl,7,8-C{sub 2}B{sub 9}H{sub 10}){sub 2}] and [(CH{sub 3}){sub 3}NH][Co(10-Br,7,8-C{sub 2}B{sub 9}H{sub 10}){sub 2}], respectively. [PPN][Co(10-Cl,7,8-C{sub 2}B{sub 9}H{sub 10}){sub 2}] (PPN = bis(triphenylphosphine)nitrogen(1+)) crystallizes in the monoclinic space 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) {angstrom}{sup 3}, Z = 4, and R = 0.054. The structure was determined by X-ray crystallography using 6830 independent reflections.