Spectroscopic studies on bis(1-amidino-O-alkylurea) copper(II) sulfate complexes where alkyl = methyl, ethyl, n-propyl or n-butyl: EPR evidence for binuclear complexes

Four new Cu(II) Complexes viz [Cu(II)(1-amidino-O-methylurea)(2)]SO4 2H(2)O (1), [Cu(II)(1-amidino-O-ethylurea)(2)](SO4)(2) 2H(2)O (2), [Cu(II)(1-amidion-O-n-propylurea)(2)]SO4 2H(2)O (3). [Cu(II)(1-amidino-O-n-butylurea)(2)](2)(SO4)(2) 2H(2)O (4) have been synthesized and characterized EPR spectrum of complex 4 at RT consisted of fine-structure transitions (Delta Ms = +/- 1) with zero-field splitting (ZFS) of 0 0485 cm(-1) and a half-field signal (Delta MS = +/- 2) at ca 1600 G, revealed formation of binuclear complex (S = 1) Whereas EPR spectrum of complex 2 in DMSO showed a mixture of mononuclear and binuclear complex in the ratio 0 75: 1.0 with ZFS of 0.0385 cm(-1) From the temperature dependence of the EPR signal intensity, the isotropic exchange-interaction constant J was evaluated. (C) 2009 Elsevier B V. All rights reserved