Dicopper(i) complexes with the chelating dmapm ligand [dmapm = 1,1-bis{di(o-N,N-dimetylanilinyl)phosphino}methane] have been synthesized and characterized structurally. Synthesis of the acetonitrile adduct [Cu2(μ-dmapm)(CH3CN)2][BF4]2 () has been presented and the dicopper electrophile has been used as the starting material in reaction with Group 14 heteroborates. Coordination of the closo-borates at the dicopper moiety resulted in different molecular structures with varying CuCu distances. In the case of the side on coordinated stanna-closo-dodecaborate the tin vertex has been characterized by (119)Sn Mössbauer spectroscopy and the nucleophilicity at the tin was established in reaction with a molybdenum carbonyl complex.