SYNTHESIS AND SPECTRAL AND STRUCTURAL CHARACTERIZATION OF A BRIDGING CHLOROPICOLINATOCOPPER(II) COMPLEX, CU(C5H4NCOO)CL

The title complex of copper(II) chloride with picolinic acid was prepa red and characterized by spectroscopic and X-ray crystallographic meth ods. The complex, Cu(C5H4NCOO)Cl, crystallizes tetragonal, space group P4(2)/n (No. 86), a = 976.4(1), c = 1499.6(4) pm, N = 8; R(w) = 0.048 for 543 observed MoK alpha diffractometer data. In the structure of t he complex two mu-chloro bridges form only slightly bent Cu2Cl2 rings [Cu-Cl = 224.2(4) and 275.6(4) pm] with Cu...Cu separation of 359.4(2) pm and Cl...Cl separation of 348.7(5) pm. These edge-sharing copper c oordination polyhedra are further linked via the N and O donor atoms o f the picolinato anions at Cu-N distances of 199.6(12) pm and Cu-O bon d lengths of 195.7(8) and 200.6(10) pm, to form a two-dimensional laye r structure in which these layers are arranged along the ab plane. Eac h picolinate anion functions as a tetra-dentate ligand: N(1) and O(2) are coordinated to the same Cu(II) center whereas O(1) is bonded to a neighbouring Cu(II) center. O(2) is further bonded to the latter Cu(II ) center at a long Cu-O distance of 256.5(8) pm. The electronic, infra red and Raman spectra of the solid complex are reported and discussed.