Synthesis of novel carboranyl amidines

The nucleophilic addition reactions of primary and secondary amines to the ethylnitrilium derivative of nido-carborane 10-EtC N-7,8-C2B9H11 were studied and a series of new nido-carboranyl amidines 10-EtC(N(R)R') = HN-7,8-C2B9H11 was prepared. It was found that the nucleophilic addition of primary amines to 10-EtC N-7,8-C2B9H11 leads to mixtures of E- and Z-isomers, whereas the addition of secondary amines results in the formation of solely E-isomers. The crystal molecular structures of E-10-EtC(NEt2) = HN-7,8-C2B9H11 and E-10-EtC(NC4H8O) = HN-7,8-C2B9H11 were determined by single crystal X-ray diffraction study. (C) 2020 Elsevier B.V. All rights reserved.