Novel sulfur containing derivatives of carboranes and metallacarboranes

A series of newcloso- andnido-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 ofnido-carborane 9-R(Me)S-7,8-C2B9H11and 10-R(Me)S-7,8-C2B9H11with 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 innido-carborane alkylmethyl sulfonium derivatives 9-XCH2S(Me)S-7,8-C2B9H11and 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 –transoidin the case of the 8,8′-isomer andgauchein the case of the 4,4′- and 4,7′-isomers.