ESR Investigation of the Adducts of Planar Copper Complexes
Journal of Structural Chemistry
, E-ISSN: 1573-8779
Institute of Catalysis, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk
The ESR method was used to analyze the structure of the adducts formed during the interaction of electroneutral Cu(II) bis-chelates with donor bases. An adduct structure with both axial and planar coordination of the added molecule can be realized depending on the donor - acceptor properties of the chelate and base. Additional coordination involves the weakening of the bonds in the original tetragonal complex, and it is proposed that the basic effect in the observed increase of the gfactor in the adducts with axial bonding is secured through the destabilization of the bonds between
the ion and the equatorial ligands. The data obtained on the structural transformations, which occur with a planar complex as a result of the additional coordination, permit one to explain the origination of the paramagnetic contact shifts of the NMR signal in the Cu(II) adducts.