Structure and spectral study of copper(II) pyridinecarboxylates:: crystal and molecular structure of trans-diaqua-bis(N,N-diethylnicotinamide-N)bis(2-chloronicotinate-O)copper(II)

New copper(II) pyridinecarboxylate compounds of the composition [CuX2(Et(2)nia)(2)(H2O)(2)] (where X = 2-methylthionicotinate (2-MeSnic). 2-chloronicotinate (2-Clnic), 2,6-dichloronicotinate (2,6-Cl(2)nic), isonicotinate (isonic) and Et(2)nia = N,N-diethylnicotinamide) have been prepared. All the [CuX2(Et(2)nia)(2)(H2O)(2)] compounds seem to possess octahedral copper(II) stereochemistry with differing tetragonal distortions. An X-ray analysis of [Cu(2-Clnic)(2)(Et(2)nia)(2)(H2O)(2)] was carried out and it featured a tetragonal-bipyramidal geometry around the copper(II) atom. The tetragonal plane is created by 2-chloronicotinate anions bonded to the copper(II) atom via the unidentate carboxylate oxygen atoms [Cu-O1 = 1.965(2) Angstrom] and the pyridine ring nitrogen atoms of the neutral ligand N,N-diethylnicotinamide [Cu-N1 = 2.015(2) Angstrom], whilst in axial positions are water molecules [Cu-O1w = 2.503(2) Angstrom]. (C) 2002 Elsevier Science Ltd. All rights reserved.