title: EPR study on ligand-exchange reaction between bis(diethyldiselenocarbamato)copper(II) and some bis(acetylacetonato)copper(II) complexes.
abstract: The paper is a study on the formation and properties of mixed-chelate copper(II) complexes, in which one ligand is strongly covalently bound diselenocarbamate (dsc), and the other belongs to a series of differently substituted acetylacetonates (acac), all forming weak covalent bonds. Thenoyltrifluoro- and trifluoro- substituted acetylacetonates only partly form mixed-chelate complexes, stable in toluene, benzene or dichloromethane, but gradually decomposing in chloroform or carbontetrachloride by analogy with Cu(Et2dsc)2 behavior in these solvents. Hexafluoro-acetylacetonato copper(II) completely turns into a mixed-chelate Cu(dsc)(hfacac), which remains unchanged for more than 8 months of monitoring in all solvents used. The stability of Cu(dsc)(hfacac) is attributed to the reduced remaining negative charge on selenium atom embarrassing the formation of weak D-A complex with haloalkanes. The obtained EPR parameters suggest significant lowering of the contribution of the 4s AO of copper(II) in the mixed-chelate complexes. It is shown that Cu(acac)2 does not react with Cu(Et2dsc)2.
authors.affiliation: Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
authors.forename: Anna
authors.initials: A
authors.lastname: Dimitrova
authors.forename: Christina
authors.initials: C
authors.lastname: Taseva
authors.forename: Nicola D
authors.initials: ND
authors.lastname: Yordanov
mesh_terms: D000096:Acetone / Q000737:chemistry*; D000107:Acetylation; D002219:Carbamates / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005030:Ethylenes / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D018036:Selenium Compounds / Q000737:chemistry*
chemical_list: D002219:Carbamates; D005030:Ethylenes; D008024:Ligands; D018036:Selenium Compounds; D000096:Acetone; D003300:Copper; C036216:ethylene