Synthesis and characterization of new ammine Ru(II) complexes containing P(m-tol)3, P(p-CH3)3 and P(OC5H11)3

Abstract

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](PF6) 2 (2a), trans-[Ru(NH3)4{P(p-tol)3}2](PF 6)2 (3b) and trans-[Ru(NH3)4{P(OC5H11) 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 × 10-3 s-1 (25°C, 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 × 10-3 s-1 [L = P(p-tol)3, 3b] and 3.5 × 10-3 s-1 [L = P(OC5H11)3 3c] (25°C, μ = 0.10 mol L-1) (NaCF3COO/CF3COOH; CH+= 1.0 × 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 × 10-3 CF3COOH]. The following reactions: trans-[Ru(NH3)4(L)H2O]+2 + pz (4a-4c) k1⇌⇋k1 trans-[Ru(NH3)4(L)pz]2++ H2O (5a-5c) [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, 5.8×10-1 s-1, and 21 mol-1 L [L = P(OC5H11)3, 4c], [25.0 ± 0.2°C; m = 0.10 mol L-1; NaCF3COO; CH+ = 1.0 × 10-3 CF3COOH].