Uma, Rajendran ; Viswanathan, Rathinam ; Palaniandavar, Mallayan ; Lakshminarayanan, M. (1994) Copper(II) complexes of novel tripodal ligands containing phenolate and benzimidazole/pyridine pendants: synthesis, structure, spectra and electrochemical behaviour Journal of the Chemical Society, Dalton Transactions (4). pp. 1219-1226. ISSN 0300-9246
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Official URL: http://pubs.rsc.org/en/Content/ArticleLanding/1994...
Related URL: http://dx.doi.org/10.1039/DT9940001219
Abstract
Mononuclear copper(II) complexes of tri- and tetra-dentate tripodal ligands containing phenolic hydroxyl and benzimidazole or pyridine groups have been isolated. They are of the type [CuL(X)]·nH2O, [CuL(H2O)]X·nH2O or [CuL]·nH2O where X = Cl-, ClO4-, N3- or NCS- and n= 0-4. The electronic spectra of all the complexes exhibit a broad absorption band around 14 000 cm-1 and the polycrystalline as well as the frozen-solution EPR spectra are axial, indicating square-based geometries. The crystal structure of [CuL(Cl)][HL =(2-hydroxy-5-nitrobenzyl)bis(2-pyridylmethyl)amine] revealed a square-pyramidal geometry around CuII. The mononuclear complex crystallises in the triclinic space group P1 with a= 6.938(1), b= 11.782(6), c= 12.678(3)Åand α= 114.56(3), β = 92.70(2), γ = 95.36(2)° . The co-ordination plane is comprised of one tertiary amine and two pyridine nitrogens and a chloride ion. The phenolate ion unusually occupies the axial site, possibly due to the electron-withdrawing p-nitro group. The enhanced p delocalisation involving the p-nitrophenolate donor elevates the E½ values. The spectral and electrochemical results suggest the order of donor strength as nitrophenolate < pyridine < benzimidazole in the tridentate and nitrophenolate < benzimidazole < pyridine in the tetradentate ligand complexes.
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Deposited On: | 27 Dec 2010 06:55 |
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