With the use of oxidative insertion of tin(II) acetylacetonate (acac) into mercuric derivatives of carboranes, new types of polymetallic chainlike compounds were obtained in which the acac ligands occupy cis positions on the tetravalent hexacoordinated tin. In was found that in benzene the insertion of Sn(acac)2 into unsymmetrical B-carboranylmercuric derivatives proceeds at the BHg bond, whereas