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Title: Complexes of bivalent transition metals with sulphur donor ligands
Author: Patel, Rameshbhai Ragjibhai
ISNI:       0000 0001 3476 1965
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1971
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The following new thiourea(tu) complexes of cobalt(II) halides Co(tu)[4]Br[2], Co(tu)[4]I[2], and the known complex Co(tu)[3] Cl[2] have been prepared. In addition, new nickel(ll) complexes with several substituted thioureas such as dibutylthiourea (dbtu), and dicyclohexylthiourea (dctu) have been prepared. Examples of these complexes are: Ni(dbtu)[4]X[2], where X = Cl, Brorl; Ni(dctu)[2]X[2], where X = ClorBr; and Ni(dctu)[6]X[2], where X = BrorI. Their visible spectra and magnetic properties show the thiourea complexes of cobalt(ll), including Co(tu)[3]Cl[2] , to be four co-ordinate and tetrahedral. The last compound was previously said to be five co-ordinate. The infra-red spectra of the thiourea complexes of cobalt(II), and of the substituted thiourea complexes of nickel(II) indicate that the ligands are bonded through sulphur and not through nitrogen. Some new complexes of chromium(ll), iron(ll) and vanadium(Il) with sulphur-donor ligands have been prepared under anaerobic conditions, and their properties investigated by spectroscopic and magnetic techniques, also carried out in the absence of air. Two types of chromium(ll) complex, Cr(R[2]NCS[2])[2] and Cr(R[2]NCS[2]Cl), R= CH[3] or Et, have been prepared from the sodium salts of diethyl- and dimethyl-dithiocarbamates under different conditions, whilst only the first type of chromium(ll) compound has been obtained from pyrrolidyl-dithiocarbamate (R = C[4]H[8]) in conditions tried. Chromium(ll) complexes of other disubstituted dithiocarbamates could not be isolated because of oxidation, apparently by the solvent, even under nitrogen. Some new iron(ll) dithiocarbamate complexes have also been prepared by the reaction of ferrous sulphate heptahydrate in water. Sodium dicyclohexyldithiocarbamate gave a complex of the type Fe[R[2]NCS[2](OH)], R = C[6]H[11]. Other sodium dithiocarbamates gave complexes of the type Fe(R[3]NCS[2])[2]; where R = CH[3], C[2]H[5], C[3]H[7], C[4]H[9] or C[4]H[8]. In addition the following two types of dxthiocarbaraato-complex of vanadium(ll) have been prepared: (1) V(R[2]NCS[2])[2]; where R = CH[3] , C[2]H[5] or C[6]H [5]CH[2], and (2) V[R[2]NCS[2](OH)]; where R = C[3]H[7], C[4]H[9] or C[4]H[8]. The reduced and temperature variable magnetic moments of the chromium(ll) and iron(II) complexes have been shown to arise from antiferromagnetic interaction in binuclear structures. The magnetic moments of the vanadium(ll) complexes are reduced, and in some cases do not vary with temperature, so that it is very difficult to say whether the metal atom is in the bivalent state or whether oxidation has occurred. The reflectance spectra of the bis(dithiocarbamato)-complexes of chromium(II) and iron(ll) are as expected for highly distorted complexes, and are therefore compatible with the binuclear five-co-ordinate structures previously assigned on the basis of X-ray powder results. Two new complexes of chromium(ll) with 2-methylmercaptoaniline have been prepared and their properties investigated by spectroscopic and magnetic techniques.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available