Experimental and theoretical study of the kinetics of dissociation in cis-[RuCl2(P-P)(N-N)] type complexes

Journal of the Brazilian Chemical Society

Marcos C. R. Monteiro²  Fabio B. Nascimento¹  Eliana M. A. Valle¹  Javier Ellena¹  Eduardo E. Castellano¹  Alzir A. Batista¹  Sergio De Paula Machado² 

[1] ,Universidade Federal do Rio de Janeiro Instituto de Química Rio de Janeiro RJ ,Brazil

关键词: DFT;    ruthenium complexes;    trans-effect;    kinetics;    dissociation;   

DOI  :  10.1590/S0103-50532010001000027

来源: SciELO

【 摘 要 】

The substitution reactions [RuCl2(P-P)(N-N)] + L → [RuCl(L)(P-P)(N-N)]+ + Cl-, where P-P = 1,4-bis(diphenylphosphino)butane and N-N = 2,2´-bipyridine, 4,4´-dimethoxy-2,2´-bipyridine, 4,4´-dimethylpyridine-2,2´-bipyridine and 4,4´-dichloro-2,2´-bipyridine, L = pyridine (py) or 4-methylpyridine (4-pic), were studied under pseudo-first order conditions. The reactions proceeded by means of a dissociative mechanism. The rate constants of the substitution reactions increased as the pKa of the N-heterocyclic ligands increased and as the oxidation potential of the metal center decreased. The greater the participation of the atomic d orbitals of the metal in the HOMO, according to DFT calculations, the easier is the dissociation of the chloride from the coordination sphere of the complex. In the 31P{¹H} NMR spectra of the series of complexes of general formula [RuCl(L)(P-P)(N-N)]PF6, there are two doublets with Δσ < 1. This is consistent with products formed by dissociation of the chloride trans to one of the phosphorus atoms in the precursors.

【 授权许可】

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