The syntheses, structures, and magnetic properties of copper(II) carboxylates with bridging α-phenyl substituted carboxylato ligands and unidentate oxygen-donor ligands are reported: Cu2 (O2CCPh2Me)4(acetone)2 (1), triclinic , a = 15.441(4), b = 15.602(4), c = 12.790(2) Å, α = 106.52(2), β = 92.11(2), γ = 96.38(2)°, V = 2928(1) Å3, Z = 2, −2J = 352 cm−1; [Cu2(O2CCPh2Me)4(H2O)2]·H2O (2), triclinic , a = 13.895(2), b = 14.717(2), c = 7.318(1) Å, α = 95.67(1), β = 101.71(1), γ = 68.12(1)°, V = 1359.3(4) Å3, Z = 1, −2J = 344 cm−1; [Cu2(O2CCPh2Me)4(EtOH)2]·EtOH (3), monoclinic P21/c, a = 26.927(5), b = 9.152(3), c = 26.881(5) Å, β = 115.02(1)°, V = 6003(2) Å3, Z = 4, −2J = 347 cm−1; [Cu2(O2CCPh3)4(Ph3CCO2H)2]·CH2Cl2 (4), monoclinic P21/c, a = 18.133(8), b = 23.046(7), c = 25.013(7) Å, β = 101.01(3)°, V = 10268(5) Å3, Z = 4; [Cu2(O2CCPh3)4(H2O)2]·4H2O (5a), tetragonal , a = 18.451(6), c = 10.703(7) Å, V = 3643(3) Å3, Z = 2; [Cu2(O2CCPh3)4(H2O)2]·2H2O (5b), tetragonal , a = 18.224(2), c = 10.776(5) Å, V = 3578(1) Å3, Z = 2, −2J = 292 cm−1; and Cu2(O2CSiPh3)4(EtOH)2 (6), monoclinic C2/c, a = 21.811(3), b = 17.366(3), c = 21.221(4) Å, β = 91.19(1)°, V = 8036(2) Å3, Z = 4, −2J = 1193 cm−1. The factors which influence the cage and coordination sphere geometry in dimeric α-phenyl substituted copper(II) carboxylates are discussed based on the above structures and the reported structures with unidentate nitrogen- and oxygen-donor ligands. In 4 and 5, intramolecular steric effects between the bulky triphenylacetato ligands result in a considerable distortion of the cage geometry. The distortion of the coordination sphere geometry around copper(II) in the complexes from square pyramidal toward trigonal bipyramidal reduces the spin-exchange interaction.