Binuclear copper(II) complexes of 1-amidino-O-alkylurea (alkyl = n-propyl, n-butyl, or i-butyl) and vanadate: an EPR study

Abstract

Five new complexes of bis(1-amidino-O-alkylurea)Cu(II)vanadate where alkyl = methyl, ethyl, n-propyl, n-butyl or i-butyl have been synthesized by reaction of ammonium metavanadate with bis(1-amidino-O-alkylurea)Cu(II)perchlorate complexes. Electron paramagnetic resonance (EPR) spectra of bis(1-amidino-O-n-propylurea)Cu(II)vanadate (1), bis(1-amidino-O-n-butylurea)Cu(II)vanadate (2) and bis(1-amidino-O-i-butylurea)Cu(II)vanadate (3) gave half-field signal (ΔM _s = ±2) ca 1623G, in addition to fine structure due to zero field splitting (ZFS) characteristics of the S = 1 system. From the observed ZFS the average Cu–Cu distance was estimated. The isotropic exchange constant J was evaluated by recording EPR spectra at different temperatures. The photoacoustic signal of the complexes indicated square-planar geometry around Cu²⁺. X-ray powder diffraction studies on 2 suggested orthorhombic structure with unit cell dimensions a = 21.11 Å, b = 24.11 Å, c = 27.11 Å, α = β = γ = 90°. The crystal structure of bis(1-amidino-O-n-butylurea)Cu(II)perchlorate is also reported.

Keywords:

• Binuclear
• Ferromagnetic
• EPR
• Vanadate ion
• Photoacoustic signal

Acknowledgments

The authors are grateful to the Head, Radiochemistry Division, BARC, for his keen interest in this work.