Mechanism for the formation of substituted manganese(V) cyanidonitrido complexes: crystallographic and kinetic study of the substitution reactions of trans-[MnN(H2O)(CN)4]2- with monodentate pyridine and bidentate pyridine-carboxylate ligands.

Dissolution of [(CH(3))N](2)Na[MnN(CN)(5)]·H(2)O in water results in the rapid dissociation of the trans-CN(-) ligand to form trans-[MnN(H(2)O)(CN)(4)](2-)(aq), which reacts with monodentate pyridine ligands such as 3-methyl and 4-methyl pyridine to form the corresponding mono-substituted complexes, of which the molecular structures obtained from X-ray crystallography, trans-[MnN(3-pic)(CN)(4)](2-) and trans-[MnN(4-pic)(CN)(4)](2-), are reported. [MnN(H(2)O)(CN)(4)](2-)(aq) also reacts with bidentate nucleophiles such as pyridine-2-carboxylate (pico) and quinoline-2-carboxylate (quino), yielding the corresponding [MnN(η(2)-pico)(CN)(3)](2-) and [MnN(η(2)-quino)(CN)(3)](2-) complexes as determined by X-ray crystallography. The formation kinetics of pyridine-2-carboxylate and three different pyridine-2,x-dicarboxylate ligands (x = 3, 4, 5) are reported, and two consecutive reaction steps are proposed, defined as the formation of the [MnN(η(1)-pico)(CN)(4)](3-) and [MnN(η(2)-pico)(CN)(3)](3-) complexes, respectively.