A series of novel cobalt bis(dicarbollide) based amidines were synthesized by the nucleophilic addition of primary and secondary amines to highly activated B-N+≡C–R triple bond of the propionitrilium derivative [8-EtC≡N-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]. The reactions with primary amines result in the formation of mixtures of E and Z isomers of amidines, whereas the reactions with secondary amines lead selectively to the E-isomers. The crystal molecular structures of E-[8-EtC(NMe2)=HN-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)], E-[8-EtC(NEt2)=HN-3,3′-Co(1,2- C2B9H10)(1′,2′-C2B9H11)] and E-[8-EtC(NC5H10)=HN-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] were determined by single crystal X-ray diffraction.
