Abstract
The synthesis and characterisation of the Schiff-base ligand, HL(1) [N-(1H-pyrrol-2-ylmethylene)-2-pyridineethanamine; derived from 2-formylpyrrole and 2-(2-aminoethyl)pyridine] and copper(II) complexes of (L(1))(-) in the form of [Cu(2)(L(1))(2)(m-X)(2)] (X= Cl(-), 1; X = Br(-), 2; X = N(3)(-), 3; X = NCS(-), 4) are reported. Bromination of the beta position on the pyrrole ring of (L1)- was observed in the preparation of the di(mu-bromo)-bridged complex [Cu(2)(L(1))(2)(mu-Br)(2)] (2), and the copper(II) complex of the brominated pyrrole derivative (L(1a))(-), 5, was also obtained. Procedures to synthesise analytically pure samples of 2 and 5 were developed. X-Ray structure determinations carried out on 1, 2, 3 and 5 reveal that 1, 2 and 3 are all doubly-bridged square pyramidal copper(II) dimers [Cu(2)(L(1))(2)(mu-X)(2)] while 5 is an unusual mono(mu-bromo)(-) bridged square pyramidal copper(II) 1D chain polymer of the brominated ligand (L(1a))(-), [Cu(L(1a))(mu-Br)](infinity). In the case of [Cu(2)(L(1))2(mu-N(3))(2)] (3) the structure determination reveals that the azide groups bridge the two copper(II) ions in a 1,1-N(3), end-on, fashion. Variable temperature magnetic susceptibility measurements carried out on the structurally characterised dimeric and polymeric copper(II) complexes 1, 2, 3 and 5, revealed weak antiferromagnetic exchange.