Croatica Chemica Acta, Vol. 82 No. 1, 2009.
Original scientific paper
On the Magnetic Exchange Parameter for an O−Cu−Cu−O Component of CuII Carboxylate Dimers
Richard D. Harcourt
; School of Chemistry, The University of Melbourne, Victoria 3010, Australia
Abstract
Two approximate formulae are derived for the magnetic exchange parameter, J = ½{E(singlet) – E(triplet)}, for an O−Cu−Cu−O component of CuII carboxylate dimers. The derivations use standard valence bond and molecular orbital techniques, but the effects of superexchange are incorporated in different ways. A superexchange parameter k measures the extent of delocalization of oxygen lone-pair electrons into singly occupied 3dx2 - y2 atomic orbitals of the CuII ions. The two formulae for J are equivalent only when k = 0 and k = ∞. The formulae are compared, and suggestions are made for elaborations of them. The roles of two types of “cis O−O overlap” for stabilizing (via covalent-ionic resonance) the antiferromagnetic spin state are re-stated for 10-electron 6-centre (with two carboxylate ligands) as well as the 6-electron 4-centre bonding units.
Keywords
copper carboxylate dimer; antiferromagnetism; magnetic exchange parameter; superexchange; “cis O−O overlap”
Hrčak ID:
38647
URI
Publication date:
30.6.2009.
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