Auxiliary part of ligand mediated unique coordination chemistry of copper (II)

Abstract

Six N, N, O-donor Schiff-base ligands, HL1-HL6, [HL1/HL2/HL3= {2-(2-piperazin-1-yl) ethylimino) methyl)-4-(Cl/H/Me)-phenol}; HL4/HL5/HL6={2-(2-morpholine/piperidine/pyrrolidine 1-yl) ethylimino) methyl)-4-chlorophenol}, have been designed by combining 5-R-2-hydroxy-benzaldehyde, (R= Cl/H/Me) and N-(2-aminoethyl)- Y,(Y=piperazin/morpholine/piperidine/pyrrolidine) with the view to explore the role of R and X (part of Y excluding coordinating N) on the coordination chemistry of Cu (II) in presence of bromide as counter anion. HL1-HL6 formed in situ on reaction with Cu(II) Br-2 produce complexes 1-6, re-spectively. Complex 1, [Cu(II)(2)Cu(I)(2)(L1)(MeOH)(2)Br-7.30], is a mixed valence Cu(I)-Cu(II) species having phenyl ring brominated at ortho position with 0.65 occupancy. Complexes 2-4 are mononuclear species with general formula [Cu{L2/L3/L4)} Br2]. Complexes [Cu-3(L5)Br-4] (5) and [Cu-3(L6) Br-4] (6) are trinuclear species having similar structure but exhibit different magnetic property, 5 is ferro-(J= + 16.64 cm(-1)) and 6 is antiferromegnetic (J= -11.76 cm (-1)). The influence of R and X on bromonation, magnetic property and nuclearity issues have been rationalized by DFT calculations.