Sundaravel, Karuppasamy ; Suresh, Eringathodi ; Palaniandavar, Mallayan (2010) Iron(III) complexes of tridentate N3 ligands as models for catechol dioxygenases: stereoelectronic effects of pyrazole coordination Inorganica Chimica Acta, 363 (12). pp. 2768-2777. ISSN 0020-1693
Full text not available from this repository.
Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00201...
Related URL: http://dx.doi.org/10.1016/j.ica.2010.04.025
Abstract
The iron(III) complexes of the tridentate N3 ligands pyrazol-1-ylmethyl(pyrid-2-ylmethyl)amine (L1), 3,5-dimethylpyrazol-1-ylmethyl(pyrid-2-ylmethyl)amine (L2), 3-iso-propylpyrazol-1-ylmethyl(pyrid-2-ylmethyl)amine (L3) and (1-methyl-1H-imidazol-2-ylmethyl)pyrid-2-ylmethylamine (L4) have been isolated and studied as functional models for catechol dioxygenases. They have been characterized by elemental analysis and spectral and electrochemical methods. The X-ray crystal structure of the complex [Fe(L1)Cl3] 1 has been successfully determined. The complex possesses a distorted octahedral coordination geometry in which the tridentate ligand facially engages iron(III) and the Cl- ions occupy the remaining coordination sites. The Fe-Npz bond distance (2.126(5) Å) is shorter than the Fe-Npy bond (2.199(5) Å). The systematic variation in the ligand donor substituent significantly influences the Lewis acidity of the iron(III) center and hence the interaction of the present complexes with a series of catechols. The catecholate adducts [Fe(L)(DBC)Cl], where H2DBC = 3,5-di-tert-butylcatechol, have been generated in situ and their spectral and redox properties and dioxygenase activities have been studied in N,N-dimethylformamide solution. The adducts [Fe(L)(DBC)Cl] undergo cleavage of DBC2- in the presence of dioxygen to afford major amounts of intradiol and smaller amounts extradiol cleavage products. In dichloromethane solution the [Fe(L)(DBC)Cl] adducts afford higher amounts of extradiol products (64.1-22.2%; extradiol-to-intradiol product selectivity E/I, 2.6:1-4.5:1) than in DMF (2.5-6.6%; E/I, 0.1:1-0.4:1). The results are in line with the recent understanding of the function of intra- and extradiol-cleaving catechol dioxygenases.
Item Type: | Article |
---|---|
Source: | Copyright of this article belongs to Elsevier Science. |
Keywords: | Iron(III) Complexes; Tridentate N3 Ligands; Facial Coordination; Catechol Dioxygenase Mimics; Electronic Effects |
ID Code: | 31007 |
Deposited On: | 27 Dec 2010 06:48 |
Last Modified: | 05 Mar 2011 04:45 |
Repository Staff Only: item control page