Copper(II) chloride adducts with nicotinic and isonicotinic acid N-oxides

Abstract

CuL nCl 2 complexes are formed by interaction of nicotinic (n = 4) or isonicotinic (n = 1) acidd N-oxide and CuCl 2 solutions in ethanol-triethylorthofromate. The 1:4 CuCl 2 adduct with nicotinic acid N-oxide seems to be a dimer of the [L 3ClCuL 2CuClL 3]Cl 2 type, with both terminal and briging, exclusively NO oxygen-bonded ligand groups. This compound exhibits a subnormal ambient temperature magnetic moment (1.20 βB) and temperature-dependent paramagnetic behavior. The 1:1 CuCl 2 adduct with isonicotinic acid N-oxide is apparently polymeric ([CuLcl 2] x), with the ligand functioning as tridentate, bridging, coordinating through all three (NO and COO) of its oxygens. This formulation is supported by the magnetic evidence, i.e., normal ambient temperature μ eff of 2.06 μB, and measurable antiferromagnetic exchange at lower temperatures.