A family of ruthenium aryls incorporating an η²-bonded nitrite or nitrate and a pendant imine-phenol function

Abstract

The reaction of carbonylchloro[4-methyl-6-(NR-iminio)phenolato-C²,O]bis(triphenylphosphine)ruthenium(II), Ru^II(η²-RL)(PPh₃)₂(CO)Cl (R = Ph, p-MeC₆H₄), 1, with NaY (Y = NO₂, NO₃) has afforded new organometallics of the type carbonyl(nitrito or nitrato)[4-methyl-6-(NR-imino)phenol-C²]bis(triphenylphosphine)ruthenium(II), Ru^II(η¹-RL)(PPh₃)₂(CO)(η²-Y) (2, Y = NO₂; 3, Y = NO₃). The transformation probably occurs via associative cis attack on chloride by Y^-. The reconversion 2 (3) → 1 is achievable by treating 2 (3) with excess halide. The X-ray structures of Ru(η¹-PhL)(PPh₃)₂(CO)(η²NO₂) and Ru(η¹-PhL)(PPh₃)₂(CO)(η²NO₃) have revealed the presence of (i) O,O'-chelated Y^- , (ii) monodentate PhL binding via an aromatic carbon atom lying cis to the CO molecule, and (iii) O(phenolic)···N(imine) hydrogen bonding. The interconversion between 1 and 2 (3) is attended with iminium-phenolate to imine-phenol tautomerization and a change in the rotational conformation of the RL ligand. Crystal data for the complexes are as follows. Ru(η¹-PhL)(PPh₃)₂(CO)(η²-NO₂): crystal system, monoclinic; space group, P2₁/c; a = 18.597(9) Å, b = 11.947(7) Å, c = 20.362(5) Å, β = 101.15(3)°; V = 4439(4) Å₃; Z = 4; R = 0.0427; R_w = 0.0458. Ru(η¹-PhL)(PPh₃)₂(CO)(η²-NO₃): crystal system, monoclinic; space group, P2₁/c; a = 18.726(11) Å, b = 1.857(4) Å, c = 20.443(8) Å, β = 102.77(4)°; V = 4426(3) Å₃; Z = 4; R = 0.0654; R_w = 0.0659.