Novel sulfur containing derivatives of carboranes and metallacarboranes

Abstract

A series of new closo- and nido-carborane based functional derivatives 1-X(CH2)nS-1,2-C2B10H11 (X=COOH, N3, CH(NH2)COOH) and [7-X(CH2)nS-7,8-C2B9H11]- (X=COOH, N3, NH2, CH(NH2)COOH) was prepared by alkylation of 1-mercapto-ortho-carborane. Dialkylsulfonium derivatives of nido-carborane 9-R(Me)S-7,8-C2B9H11 and 10-R(Me)S-7,8-C2B9H11 with boron-sulfur bond were prepared by alkylation of the corresponding methyl-carboranyl thioether. New types of intramolecular B-H···X and B-H···π(C?C) interactions were found in nido-carborane alkylmethyl sulfonium derivatives 9-XCH2S(Me)S-7,8-C2B9H11 and 10-RC?CCH2S(Me)S-7,8-C2B9H11, respectively. Isomeric methylsulfide derivatives of transition metal bis(dicarbollide) complexes [X,Y-(MeS)2-3,3′-M(1,2-C2B9H10)2]- (M=Co, Fe) were prepared starting from the corresponding methylcarboranyl thioethers. The intramolecular CHcarb···S(Me)S hydrogen bonding between the dicarbollide ligands in cobalt bis(dicarbollide) complexes results in stabilization of definite rotational isomers - transoid in the case of the 8,8′-isomer and gauche in the case of the 4,4′- and 4,7′-isomers.