Nitrosyl induces phosphorous-acid dissociation in ruthenium(ii)

摘要

The trans-[Ru(NO)(NH_3)_4(P(OH)_3)]Cl _3 complex was synthesized by reacting [Ru(H_2O)(NH _3)_5]~(2+) with H_3PO_3 and characterized by spectroscopic (~(31)P-NMR, δ = 68 ppm) and spectrophotometric techniques (λ = 525 nm, ε = 20 L mol~(-1) cm~(-1); λ = 319 nm, ε = 773 L mol~(-1) cm ~(-1); λ = 241 nm, ε = 1385 L mol~(-1) cm ~(-1); νNO~+ = 1879 cm~(-1)). A pK_a of 0.74 was determined from infrared measurements as a function of pH for the reaction: trans-[Ru(NO)(NH_3)_4(P(OH)_3)] ~(3+) + H_2O trans-[Ru(NO)(NH_3) _4(P(O~-)(OH)_2)]~(2+) + H _3O~+. According to ~(31)P-NMR, IR, UV-vis, cyclic voltammetry and ab initio calculation data, upon deprotonation, trans-[Ru(NO)(NH_3)_4(P(OH)_3)]~(3+) yields the O-bonded linkage isomer trans- [Ru(NO)(NH_3) _4(OP(OH)_2)]~(2+), then the trans-[Ru(NO)(NH _3)_4(OP(H)(OH)_2)]~(3+) decays to give the final products H_3PO_3 and trans-[Ru(NO)(NH _3)_4(H_2O)]~(3+). The dissociation of phosphorous acid from the [Ru(NO)(NH_3)_4]~(3+) moiety is pH dependent (k_(obs) = 2.1 × 10~(-4) s ~(-1) at pH 3.0, 25 °C).