Synthesis, crystal structure and magnetic properties of the triply bridged one-dimensional polymers {[Cu-2(ClO4)(OAc)(2)(bppz)(H2O)(2)](ClO4)(H2O)}(n) and {[Cu-2(OBz)(3)(bppz)](ClO4)(H2O)(2)}(n); bppz=2,5-bis(2-pyridyl)pyrazine

Compounds {[Cu-2(ClO4)(OAc)(2)(bppz)(H2O)(2)](ClO4)(H2O)}(n) (1) and {[Cu-2(OBz)(3)(bppz)](ClO4)(H2O)(2)}(n) (2), where bppz is 2,5-bis(2-pyridyl)pyrazine, OAc acetate and OBz benzoate, have been synthesized and characterized crystallographically. Polymer 1 crystallized in the monoclinic system, space group P2(1)/m, a = 8.305(1), b = 10.747(2), c = 15.320(2) Angstrom, beta = 101.02(1)degrees Z = 2, R1 for 1837 observed reflections [I>2 sigma(I)], measured at 213 K, was 0.0374. The structure consists of centrosymmetric dinuclear copper bppz units bridged by two acetate groups and a perchlorate anion, so forming a zig-zag one-dimensional polymer. A mirror plane bisects the three bridging groups. The copper atoms have a distorted square bipyramidal geometry. The one-dimensional polymer 2 crystallized in the triclinic system, space group P (1) over bar, a = 10.505(4), b = 11.666(3), c = 16.780(5) Angstrom, alpha = 91.87(3)degrees, beta = 102.85(4)degrees, gamma = 113.60(2)degrees, Z = 2, R1 for 3742 observed reflections [I>2 sigma(T(I)], measured at 213 K, was 0.0636. The structure is made up of two crystallographically different centrosymmetric binuclear copper bppz units bridged by three benzoate groups; two coordinate in a syn-syn manner, the third in a monodentate manner. One copper atom possesses a distorted square pyramidal geometry the other a distorted square bipyramidal geometry. Magnetic measurements for 1 and 2 show different but significant antiferromagnetic coupling with J = - 88.1 cm(-1), g = 2.18 for 1 and J = - 26.4 cm(-1), g = 2.19 for 2. The magnetic behavior may be correlated to the structural parameters.