
TY  - JOUR
A1  - Palaniandavar, M 
A1  - Natarajan, C 
T1  - Cobalt(II), nickel(II) and copper(II) complexes of some 2'-hydroxychalcones
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1980
VL  - 33
IS  - 4
SP  - 737
EP  - 745
KW  - 
UR  - https://doi.org/10.1071/CH9800737 
N2  - Metal(II) bis-chelates of the type ML2 [M = CoII, NiII, CuII; L = 2'- hydroxy-5'-X-chalcone where X = H, CH3, Cl] have been prepared and studied. Structures have been assessed by the measurement of magnetic moments, ligand field and infrared spectra and thermal properties. These chelates possess low-spin trans-square-planar configuration and show resistance to adduct formation in contrast to metal(II) chelates of &#946;-diketones, salicylaldehyde, o-hydroxyaryl ketones and esters and o-hydroxy-crotonophenones, which have high-spin octahedral configuration. Extensive conjugation lowers the energy of the &#960;3* orbital which enters into a very strong d&#960;-&#960;3* interaction leading to spin-pairing.     Infrared spectra indicate that the carbonyl group is perturbed only slightly by coordination to metal. A change in metal ion affects v(C=O), v(M-O) and other vibrations and the order of stability, namely, Co &#8776; Ni < Cu, inferred from these vibrations is as expected for the low-spin square configuration of the chelates. Introduction of substituents (5'-X) alters only v(M-O) significantly and the order of stability, namely, Cl > CH3 > H, derived from v(M-O) is consistent with Taft's resonance polar parameters of the substituents. All these observations are explained by the electron sink property of the phenyl group. 
ER  -

