Copper(II) cyanoacetate polymer: Synthesis and structure

A new copper carboxylate polymer with cyanoacetate anion as a ligand was sy nthesized and studied using X-ray diffraction, IR, and EPR spectroscopy. Th e crystal is tetragonal: a = 14.702(2) Angstrom, c = 13.470(3) Angstrom, Z = 8, space group I4(1)/a, and R = 0.0634. The copper atoms in the centrosym metric dimeric fragment have a square-pyramidal surrounding with the CuO4N coordination core and are joined through four bidentate bridging anions of cyanoacetic acid Cu(1)'-O(1A) 1.931(4) Angstrom, Cu(1)'-O(1B) 1.926(4) Angs trom, Cu(1)-O(2B) 2.018(3) Angstrom, Cu(1)-O(2A) 2.036(4) Angstrom, and Cu( 1)-N(1A)' 2.206(5) Angstrom. The Cu . . . Cu' distance in the dimer is 2.70 9 Angstrom. The copper atom is extended from the mean equatorial plane towa rd the axial nitrogen atom by 0.23 Angstrom. EPR data confirm strong anti f erromagnetic interaction (2J approximate to -275 cm(-1)) between the copper (II) ions of the dimeric fragment, whereas the interaction between the dime rs is significantly weaker (J < 0.3 cm(-1)).