A partially-unlinked cavitand, derived from the condensation of acetaldehyde and resorcinol and having three ethylene bridges, functions as a monodentate ligand toward transition metal ions. Treatment of the cavitand with MCl2 and a bidentate ligand (L) in the presence of NaOH led to isolation of metal complexes with the formula (cavitand)2ML (M = Co, Cu, Zn) or (cavitand)2ML2 (M = Ni). The square-planar complexes of Cu(II) and Co(II), the tetrahedral complex of Zn(II), and the octahedral complex of Ni(II) were characterized spectroscopically and in one case by X-ray crystallography. Crystals of Cu(II) complex 4 (C116H133Br8CuN11O18) belong to the triclinic space group P1BAR with a = 13.854(3) angstrom, b= 21.602(5) angstrom, c = 22.743(6) angstrom, alpha = 110.091(21)degrees, beta = 98.540(22)degrees, gamma = 103.922(21)degrees, V = 6002(3) angstrom3, and Z = 2.