Synthesis and structure of 1,12-diethynyl-para-carborane

Base desilylation of the novel compound, 1,12-bis(trimethylsilylethynyl)-pa ra-carbonate 1,12-(Me,SiC=C)(2)-1,12-C2B10H10, gave the previously unknown compound 1,12-bis(diethynyl)-para-carborane, 1,12-(HC=C)(2)-1,12-C2B10H10. In the structure of the latter carborane, determined by X-ray diffraction, the ethynyl substituents induce a distortion of the carborane icosahedron, lengthening the tropical B-B bonds. The structural parameters of the diethy nyl carborane are compared with known structures of type 1,12-(XE)(2)B10H10 bearing substituents on antipodal sites particularly the isostructural and isoelectronic 1,12-B12H10(CO)(2). (C) 2000 Elsevier Science S.A. All right s reserved.