Synthesis of Boronated Amidines by Addition of Amines to Nitrilium Derivative of Cobalt Bis(Dicarbollide) †

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-C(2)B(9)H(10))(1′,2′-C(2)B(9)H(11))]. 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(NMe(2))=HN-3,3′-Co(1,2-C(2)B(9)H(10))(1′,2′-C(2)B(9)H(11))], E-[8-EtC(NEt(2))=HN-3,3′-Co(1,2- C(2)B(9)H(10))(1′,2′-C(2)B(9)H(11))] and E-[8-EtC(NC(5)H(10))=HN-3,3′-Co(1,2-C(2)B(9)H(10))(1′,2′-C(2)B(9)H(11))] were determined by single crystal X-ray diffraction.