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Journal of the Brazilian Chemical Society

Print version ISSN 0103-5053

Abstract

SIGNINI, Roberta  and  MAZZETTO, Selma E.. Synthesis and Characterization of New Ammine Ru(II) Complexes Containing P(m-tol)3, P(p-CH3)3 and P(OC5H11)3. J. Braz. Chem. Soc. [online]. 2002, vol.13, n.5, pp. 647-652. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50532002000500017.

Direct reactions between [Ru(NH3)5(H2O)](PF6) 2 (1) and P(m-tol)3 (a), P(p-tol)3 (b) and P(OC5H11)3 (c) lead the complexes [Ru(NH3)5P(m-tol)3](PF 6)2 (2a), trans-[Ru(NH3)4{P(p -tol)3}2](PF6)2 (3b) and trans-[Ru(NH3)4{P(OC5H 11)3}2](PF6)2 (3c) respectively. These complexes have been isolated as hexafluorophosphate salts and characterized by elemental analysis, cyclic voltammetry and UV-VIS spectra measurements. One ammonia ligand in 2a is displaced at the a specific rate of 4.3 x 10-3 s-1 (25 oC, μ = 0.10 mol L-1). The aquo species trans-[Ru(NH3)4(L)H2O] 2+ (L = P(p-tol)3, 4b; L = P(OC5H11)3, 4c) are generated by the substitution of one L ligand with H2O, from trans-[Ru(NH3)4(L)2]2+ with k-1 = 2.7 x 10-3 s-1 [L = P(p-tol)3, 3b] and 3.5 x 10-3 s-1 [L = P(OC5H11)3 3c] (25 oC, μ = 0.10 mol L-1) (NaCF3COO/CF3COOH; CH+ = 1.0 x 10-3 mol L-1). The formal reduction potentials for the species 3b, 3c and 2a are 0.50 ± 0.01V, 0.48 ± 0.01V and 0.50 ± 0.02V, respectively (vs SCE) [μ = 0.10 mol L-1 ; NaCF3COO; CH+ = 1.0 x 10-3 CF3COOH]. The following reactions: [L = P(m-tol)3, P(p-tol)3 and P(OC5H11)3] were studied and the calculated values for k1, k-1 and Keq are 0.28 mol-1 L s-1, 0.06 s-1, 4.67 mol-1 L [L = P(m-tol)3, 4a]; 0.25 mol-1 L s-1, 0.04 s-1, 6.25 mol-1 L [L = P(p-tol)3, 4b]; 12.4 mol-1 L s-1, 5.8x10-1 s-1, and 21 mol-1 L [L = P(OC5H11)3, 4c], [25.0 ± 0.2 oC; m = 0.10 mol L-1; NaCF3COO; CH+ = 1.0 x 10-3 CF3COOH].

Keywords : ruthenium(II); ammine complexes; phosphine; phosphite ligands.

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