Synthesis, characterization and reactivity of the propionitrile complexes of ruthenium(II) and ruthenium(III)

Abstract

The complexes [Ru(NH 3) 5(NCC 2H 5)](PF 6) n ( n = 2, 3) have been isolated and characterized by microanalysis, cyclic voltammetry, UV-vis and IR spectroscopies. In acidic media, C H+ = 1 × 10 −3 M, μ = 0.10 M (NaCF 3COO) at (25.±0.1)°C, the complex ion [Ru(NH 3) 5(NCC 2H 5)] 2+ undergoes aquation yielding the trans-[Ru(NH 3) 4(NCC 2 H 5)(H 2O)] 2+ ion, with k −NH 3 equal to (1.2±0.1) × 10 −5 s −1. The specific rates k 1, k −1 and K eq for the reaction: ▪ are, respectively, 8.6×10 −3 M −1 s −1, 1.6×10 −5 s −1 and 5.4 × 10 2 M −1, under the same experimental conditions described above. The value for the p K a of the acid trans-[Ru(NH 3) 4(NCC 2H 5)(pzH)] 3+ was calculated as (1.6±0.1), μ = 0.1 M (NaCF 3COO) at (25.0±0.1)°C. The complex ion [Ru(NH 3) 5(NCC 2H 5)] 3+ undergoes hydrolysis in alkaline medium yielding the propanamide complex of pentaammineruthenium(III), with k OH equal to (1.9±0.1) × 10 2 M −1 s −1.