Thermal Studies of Metal-quinone Complexes Role of Aqua Coligations with Copper(II) in Coordination of 2-hydroxy-1,4-naphthoquinone |
| |
Authors: | Rane S Y Gawali S D Kumbhar A S Padhye S B Bakare P P |
| |
Institution: | (1) Department of Chemistry, University of Pune, Pune, 411 007;(2) Physical Chemistry Division, National Chemical Laboratory, Pune, 411 008, India |
| |
Abstract: | Copper(II) complexes of lawsone (2-hydroxy-1,4-naphthaquinone, Lw) with variety of aqua ligation viz. Cu-1, Cu(Lw)2(H2O)]2; Cu-2, Cu(Lw)2(H2O)2] and Cu-3, Cu(Lw)2(H2O)2]2 have been synthesized. The role of water as counter ligand on coordination propensity of redox active lawsone in naphthoquinone/naphthosemiquinone
(NQ/NSQ) forms is quantified by studies of pyrolytic reactions, using non-isothermal TG and DTA techniques, coupled with IR
studies. Mixed (NQ) (NSQ) ligation in Cu-1 and Cu-3 required energy of activation, Ea ∼67 kJ mol−1 of (NQ) and ∼41 kJ mol−1 of (NSQ). Comparable energies of aqua ligand (∼43 kJ mol−1) with NSQ ligand in Cu-1 and Cu-3, dictate charge distributions in lawsone coordinations. A large difference between Ea of aqua and p-NQ ligand indicates coordination of lawsone in its fully oxidised quinone form in Cu-2. From thermoanalytical
studies schematic oxidative decomposition mechanisms are proposed for Cu-1 and Cu-3. From pyrolytic reactions enthalpies are
estimated by DTA technique.
This revised version was published online in August 2006 with corrections to the Cover Date. |
| |
Keywords: | aqua coligations hydroxy naphthoquinone quinones |
本文献已被 SpringerLink 等数据库收录! |
|