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Reactions of coordinated ligands.

Soudi, Ali Akbar. (1979) Reactions of coordinated ligands. Doctoral thesis, University of Surrey (United Kingdom)..

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The research work described in this thesis reports the preparation, characterisation and reaction kinetics of some new complexes, mainly of cobalt(lll) and platinum(ll). The work falls into the following categories. (i) A series of linkage/geometric isomers trans-[Co-(en)[2]([-]O[2]C-(CH[2])n-NH[3+])Cl][2+] and cis-[Co(en)[2](NH[2]-(CH[2])n-[2+] CO[2]H)Cl][2+], (en=1,2-diaminoethane; n=1-3,5) containing O- and N-bonded amino acids respectively have been prepared by the reaction between trans-[Co(en)[2]Cl[2]][+] and amino acids, the product obtained depending on the pH of the reaction medium. These complexes have been characterised by a combination of near u.v. - visible, i.r. and n.m.r. spectroscopic techniques. The values of the acid ionisation constants of the complexes in aqueous solution have also been used in establishing structures. (ii) A number of complexes of the type trans-[Co(en)[2-](-O[2]C-CH(R)-NH[3+])x] (C10[4])[2], (X=Cl-, Br-; R=-H, -CH[3], -CH[2]-CH[3]) have been prepared, and kinetics of their base and Hg(II)-promoted hydrolysis reactions (leaving group X-) have been investigated. Activation parameters, Ea, DeltaH+, DeltaS+ and DeltaG+ have been derived for these reactions at 298.2 K. (iii) A series of acetate and substituted acetate complexes trans- [Co(en)[2](R-CH[2]-CO[2]-)Cl] CIO[4] has been prepared and the effect of substituents R in the non-participating acetate ligand on reactivity towards acid and base hydrolysis (loss of Cl-) has been studied. The cyano-acetate complex is three times more reactive than the acetate complex and some eighteen times more reactive than the glycine complex in base hydrolysis at 25 C. Electronegative substituents R retard rates of acid hydrolysis. The steric course of each reaction has also been investigated. (iv) The kinetics of the Hg(II)-promoted and spontaneous aquation of a number of N-bonded amino acid complexes cis- [Co(en)[2]NH[2]-(CH[2])n-CO[2]H)Cl][2+] have been studied and activation parameters for these reactions derived in each case. (v) The complex cis-[PtCl[2](Hedma)], Hedma=1,2-diami-noethane-N-monoaceticacid has been prepared and characterised. Its reactions in aqueous solution over a pH range and temperature range have been investigated. These reactions provide an example of anchimeric carboxylate group assistance in inorganic chemistry. (vi) The hydrolysis of 2-cyano-1,10-phenanthroline to the corresponding amide has been investigated in solutions containing Co(II) and the large rate enhancement observed has been attributed to an entropy effect. The effect of Cu(II) on the hydrolysis reaction at 25 C has also been studied.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Soudi, Ali Akbar.
Date : 1979
Contributors :
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1979.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 14:26
Last Modified : 06 Nov 2018 16:53

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