6533b852fe1ef96bd12ab588

RESEARCH PRODUCT

Crystal structure and spectroscopic study of [Cu(BPCA)(OH2)(O2CCH3)·H2O complex; BPC = N-2-pyridinylcarbonyl-2-pyridinecarboximidate anion

subject

description

Abstract The crystal and molecular structure of the [Cu(BPCA)(OH2)(O 2CCH3]·H2O complex (BPCA = N-2-pyridinylcarbonyl-2-pyridinecarboximidate anion) has been determined by X-ray diffraction methods. It crystallizes in the triclinic space group P l with two formula units in a cell of dimensions: a = 7.416(2), b = 8.632(4), c = 13.034(3) A, α = 74.55(3), β = 84.84(3), γ = 81.04(5)°. Least-squares refinement of 2534 reflections with I > 2.5σ(I) and 218 parameters gave a final R = 0.047 and Rw = 0.049. The structure consists of discrete [Cu(BPCA)(OH2)(O2CCH3)] neutral units linked through hydrogen bonding. The coordination geometry around copper ions can be described as tetragonal square pyramidal, the oxygen atom from the coordinated water molecule occupying the axial position. The compound loses both coordinated and lattice water upon heating, and quickly rehydrates to the initial form when it cools down to room temperature. The powder X-band ESR spectra of both the hydrated and the anhydrous forms exhibit the ΔMs = 2 absorption, indicating magnetic exchange between two copper(II) ions. The nature of this coupling is discussed on the basis of the structural features.