Nitrosyl-cobalt monocarbollide complexes

Abstract

The carborane anion [ closo-2-CB 10H 11] − undergoes a polyhedral expansion reaction with [Co(CO) 3(NO)] in tetrahydrofuran (THF) to afford [2-CO-2-NO- closo-2,1-CoCB 10H 11] −, isolated as the [N(PPh 3) 2] + salt 1a. An X-ray diffraction study confirmed that the NO group is linearly bonded to cobalt. The CO ligand in 1a is readily replaced by PPh 3 in the presence of Me 3NO, or by PEt 3 or CNBu t directly, to give the species [N(PPh 3) 2][2-L-2-NO- closo-2,1-CoCB 10H 11] [L=PPh 3 ( 1b), PEt 3 ( 1c), CNBu t ( 1d)]. Reactions of these anionic complexes with electrophilic reagents are exemplified by treatment of 1c with CF 3SO 3Me in CH 2Cl 2–THF to give the neutral, zwitterionic B-THF species [2-NO-2-PEt 3-7-O(CH 2) 4- closo-2,1-CoCB 10H 10] ( 3a), and by the reaction of 1b with [CuCl(PPh 3)] 4 and Tl[PF 6] in THF to give bimetallic [2,7,11-{Cu(PPh 3)}-7,11-(μ-H) 2-2-NO-2-PPh 3- closo-2,1-CoCB 10H 9] ( 4b). X-ray diffraction analysis of crystals of 4b confirmed the presence of a CoCu bond.