Anion-Directed Copper(II) Metallocages, Coordination Chain, and Complex Double Salt: Structures, Magnetic Properties, EPR Spectra, and Density Functional Study

A series of Cull metallo-assemblies showing anion directed structural variations, including five metallocages [(G(n-))subset of{Cu-2(Hdpma)(4)}]((8-n)+)(A-)(8-n) (G(n-) =NO3-,ClO4-, SiF62-, BF4-, SO42-; A =NO3-, ClO4-, BF4-, CH3SO4-; Hdpma bis(3-pyridylmethyl)ammonium cation), a complex double salt, namely, (H(3)dpma)(4)(CuCl4)(5)Cl-2, and a coordination chain, namely, [Cu-2(dpma)(OAc)(4)], are reported. The influence of the anion can be explained by its coordinating ability, the affinity of which for the Cu-II center interferes significantly with metallocage formation, and its shape, which offers host guest recognition ability to engage in weak metal-anion coordination and hydrogen bonding to the organic ligand, which are responsible for metallocage templation. EPR studies of these metallocages in the powder phase at room temperature and 77 K showed a trend of the g values (g(II)> 2.10>g(perpendicular to) >2.00) indicating a d(x2-y2)-based ground state with square-pyramidal geometry for the Cull centers. The magnetism of these metallocages can be interpreted as the result of a combination of relatively small magnetic coupling integrals and a substantial contribution of temperature-independent paramagnetism (TIP). The weak magnetic interaction is corroborated by the results of DFT calculations and the EPR spectra. Availability of the low-lying state for spin population was confirmed by a magnetization study, which revealed a magnetic moment approaching 2N beta, which would explain the presence of the larger TIP term.