Dicapped triangular copper(I)-dppm complexes Cu-3(dppm)(3)(mu(3)-X)(2)(+) (X = Cl, Br, and I) and monocapped Cu-3(dppm)(3)(mu(3)-OH)(2+) have been prepared by treating the dimeric Cu-2(dppm)(2)(CH3CN)(4)(ClO4)(2) or Cu-2(dppm)(2)(dmcm)(3)(BF4)(2) (dmcn = dimethylcyanamide) complexes with the corresponding bridging ligand X-. The trimeric complexes Cu-3(dppm)(3)(mu(3)-OH)(BF4)(2) and Cu-3(dppm)(3)(mu(3)-Cl)(2)Cl can be converted to dimers Cu-2(dppm)(2)(dmcn)(3)(BF4)(2) and Cu-2(dppm)(2)(dmcn)(Cl)(2) by reaction with HBF4, dmcn, and excess dmcn, respectively. The complexes synthesized by the above means, Cu-3(dppm)(3)(mu(3)-Cl)(2)ClO4 (1), Cu-3(dppm)(3)(mu(3)-Br)(2)ClO4 (2). 2THF, Cu-3(dppm)(3)(mu(3)-I)(2)I . 2CH(2)Cl(2). CH3OH (3), and Cu-2(dppm)(2)(dmcn)(Cl)(2). 2dmcn (4) have been characterized by IR, H-1 and P-31{H-1} NMR, and solid-state emission spectroscopy. The solid-state molecular structures of complexes 2, 3, and 4 were determined from single-crystal X-ray diffraction studies. Apart from confirming the nuclearity, the structural information reveals interesting variations in the Cu ... Cu distances in dimeric and trimeric complexes. A simple geometric correlation between the Cu-X and Cu ... Cu distances is noted in the trimeric complexes with an important exception of the dicapped Cl complex. Ab initio electronic structure calculations of the homo dicapped Cu3X2+ (X= Cl, Br, HO, and HC2) and mixed-capped Cu3XY+ (X = Cl, Y = HC2) species have been carried out at the MP2 level of theory using valence-DZP-quality basis sets with effective core potentials on copper. The computed Cu ... Cu distances reproduce the observed experimental trend. Analyses of the electronic structures of the optimized model Cu3X2+ complexes reveal the electronic tuning of Cu ... Cu distances by the capping ligand. The variation of Cu ... Cu distances in monobridged dimeric copper(I)-dppm complexes can also be rationalized along similar lines.