Abstract
Compounds [ Cu 2( ClO 4)( OAc) 2( bppz)( H 2 O) 2]( ClO 4)( H 2 O) n ( 1) and [ Cu 2( OBz) 3( bppz)]( ClO 4) ( H 2 O) 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) A ̊ , β=101.02(1)°, Z=2, R1 for 1837 observed reflections [1>2 σ( J)], 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 P1/, a=10.505(4), b=11.666(3), c=16.780(5) A ̊ , α=91.87(3)°, β=102.85(4)°, γ=113.60(2)°, Z=2, R1 for 3742 observed reflections [1>2 σ( 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 distroted 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.
Published Version
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