Abstract
Three copper(II) complexes of (L-1)(-), [(CuLCl)-Cl-1] (1), [(CuLBr)-Br-1](n) (2) and [Cu-2(L-1)(2)(mu(1,3)-NCS)(2)] (3), and two copper(II) complexes of HL1, [Cu(HL1)X-2] (X = Cl-, 4; X = Br-, 5), have been prepared and characterised [where HL1 is the Schiff-base ligand derived from pyrrole-2-carbaldehyde and 2-aminomethylpyridine]. The removal of a chloride ion and deprotonation of [Cu(HL1)Cl-2] (4) to form [(CuLCl)-Cl-1] (1) worked well. However, attempts to protonate [(CuLCl)-Cl-1] with HCl to reform [Cu(HL1)Cl-2] were not successful. X-ray structure determinations revealed that 1 is a N3Cl-coordinated square-planar copper(II) monomer [(CuLCl)-Cl-1], whereas 3 is a doubly end-to-end thiocyanate-bridged square-pyramidal copper(II) dimer [Cu-2(L-1)(2)(mu(1,3)-NCS)(2)]. The structure determinations on 4 and 5 showed that in both cases the copper(II) ion is in a distorted square-planay N2X2 environment, with the pyrrole NH remaining non-deprotonated and uncoordinated. Variable-temperature magnetic susceptibility investigations carried out on the end-to-end thiocyanate doubly bridged square-pyramidal copper(II) dimer 3 showed that no magnetic coupling occurs between the two copper(II) ions; it exhibits Curie-like magnetic behaviour. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)