Novel isomorphous tetranuclear complexes, [(dppf)Cu(μ3,η2 : 2 : 2-E2{CpMo(CO)2}2]BF4 [E=P (1), As (4), Sb (5), (dppf=1,1′-bis-(diphenylphosphino)-ferrocene)] and [(dppf)Cu(μ3,η2 : 2 : 2-PE{CpMo(CO)2}2]BF4 [E=As (2), Sb(3)] were synthesized from the reactions between [(dppf)Cu(MeCN)2][BF4] and tetrahedral molybdenum complexes containing unsubstituted homo- and hetero-diatomic group-15 elements [(μ,η2 : 2-E2{CpMo(CO)2}2] [E=P (A), As (D), Sb (E)] and [(μ,η2 : 2-PE{CpMo(CO)2}2] [E=As (B), Sb (C)], respectively. In all these products, the {Mo2E2} or {Mo2PE} moieties coordinate the Cu(I) center via a rare side-on η2-coordination mode. The X-ray structure analyses of [(dppf)Cu(μ3,η2 : 2 : 1-PSb{CpMo(CO)2}2][BF4] demonstrate, for the first time, the utilization of an η1-coordination mode for the ligand complex C to coordinate to the Cu(I) center. All the products were characterized by X-ray crystallography, NMR and IR spectroscopy, mass spectrometry and elemental analysis. Electrochemical studies also revealed the formation of 1–5, and, further, to understand the structure and bonding of the products, theoretical calculations using density functional theory (DFT) were conducted.