Two- and Three-Dimensional Copper 5-Sulfoisophthalate Coordination Polymers with Conformationally Flexible Dipyridyl-Piperazine Type Co-Ligands

Several divalent copper coordination polymers containing both 5-sulfoisophthalate (sip) and bis(pyridyl)piperazine type co-ligands have been hydrothermally synthesized and structurally characterized by single-crystal 19, X-ray diffraction. Across this series, the nature of the neutral co-ligands plays a crucial structure-directing role. Bis(3-pyridylmethyl)piperazine (3-bpmp) and its isomer bis(4-pyridylmethyl)piperazine (4-bpmp) afforded layered phases with different topologies. {[Cu(sip)(H3-bpmp)(H2O)]center dot 3H(2)O}(n) (1) and {[Cu(sip)(H4-bpmp)(H2O)]center dot 4H(2)O}. (2) both possess (4,4) grid topologies, although the latter exhibits mutually inclined 2D + 2D -> 3D interpenetration. {[Cu(sip)(H4-bpmp)]center dot 7.5H(2)O}(n) (3), which forms concomitantly with 2, has an uncommon (3,6) triangular grid layer based on {Cu-2(OCO)(2)} dimers. A lower temperature pseudopolymorph, {[Cu-6(sip)(6)(H(2)4-bpmp)(3)(H2O)(20)]center dot 4H(2)O}(n) (4), is an oligomeric molecular species. Employing bis(4-pyridylformyl)piperazine (4-bpfp) generated {[Cu-4(sip)(2)(OH)(2)(H2O)(3)(4-bpfp)]center dot H(2)Ob}(n) (5), which manifests {Cu-4(OH)(2)} "butterfly" clusters linked into a unique three-dimensional (3-D) 3,3,8-connected trinodal lattice with (3.4(2))(4(2)6)(3(2)4(4)5(3)6(9)7(7)8(2)9) topology. The copper clusters in 3 and 5 exhibit antiferromagnetic coupling.