Three-spin magnetic Cluster consists of manganese(II) and ortho-carboranyl biradical OCB-BNN have been synthesized and characterized as the first example of the carborane containing paramagnetic complex. The crystal structure of discrete 1: 1 complex Mn(htac)(2) center dot OCB-BNN was unambiguously determined. In the crystal structure, OCB-BNN behaves as the molecular tweezers that bind to m anuariese(II) ion. The strong antiferromagnetic interaction (J/k(B) = -181(2)K) was found between nitronyl nitroxides and manganese(H) ion.