Co-ordination chemistry of ruthenium with chelating amine ligands: synthesis and X-ray structural study of the N6-co-ordinated ruthenium(II) complex of 1,4,8,11-tetrakis(2-pyridylmethyl)-1,4,8,11-tetra-aza-cyclotetradecane

Abstract

Reaction of K₂[RuCl₅(H₂O)] with 1,4,8,11-tetrakis(2-pyridylmethyl)-1,4,8,11-tetra-azacyclotetradecane (L¹) in ethanol yielded [Ru^II(HL¹)][ClO₄]₃·H₂O (1). The E_½ value for the Ru^III/II couple is 1.17 V vs. a normal hydrogen electrode and the optical spectrum shows an intense d_π(Ru)→π*(pyridine) charge-transfer transition at 376 nm. The complex cation in (1)[space group P, a= 10.674(2), b= 14.211(3), c= 14.507(4)Å, α= 92.77(3), β= 107.28(3), γ= 105.65(2)°, U= 2 003.5(7)ų, Z= 2; R= 0.043 for 7 037 observed Mo-K_α data] is distorted octahedral with average Ru–N(tertiary amine) and Ru–N(pyridyl) bond distances of 2.191(3) and 2.075(3)Å respectively.