Coordination polymers of Cu(II) and Cd(II) with bifunctional chelates of the type dipicolylamino-alkylcarboxylate, (NC5H4CH2)2N(CH2)nCO2H (n = 1, 2, 3 and 4)

A series of bifunctional chelates of the type dipicolylamino-alkylcarboxylate (NC5H4CH2)2N(CH2)nCO2H (n = 1–4; HL1–HL4, respectively) has been prepared. Reactions of the ligands in aqueous methanol/N,N-dimethylformamide with the appropriate Cu(II) salts yielded the compounds [CuL1](NO3)·H2O (1·H2O), [CuL2(H2O)]BF4·H2O (2·H2O), [Cu(HL3)(SO4)]2 (3) and [CuL4(NO3)]·MeOH (4·MeOH). While compounds 1, 2 and 4 are one-dimensional, the detailed connectivities within the chains are quite distinct, depending on factors such as alkyl chain length and ligation of aqua ligands or anionic components. In contrast to 1, 2 and 4, the structure of 3 is molecular, a binuclear assembly of edge-sharing Cu(II) ‘4+2’ distorted octahedra. The Cd(II) species, [{CdL2}2(SO4)]·4H2O (5·4H2O), prepared from HL2 and CdSO4·nH2O in aqueous methanol/N,N-dimethylformamide, is two-dimensional, with a network constructed from binuclear units of seven coordinate Cd(II), { CdL 2 } 2 2 + , linked through bridging SO42− groups to produce an assembly of linked hexagonal rings [{CdL2}2(SO4)]6.