ISSN:
1572-8943
Schlagwort(e):
aqua coligations
;
hydroxy naphthoquinone
;
quinones
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
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.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1010121214059
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