Synthesis and characterization of nitrogen rich ruthenium complexes

Treatment of “ruthenium blue” in ethylene glycol with azide ions produced three ruthenium complexes having different nuclearities and oxidation states. The first, [Ru(N3)6]3− (1), a mono-nuclear RuIII hexaazide complex has been crystallized by using various counter-cations. The X-ray structure analysis of these salts has revealed a slightly distorted octahedral geometry with a Ru–N bond distance of 2.066(3) Å. The second, [Ru2N(N3)10]6− (2), is a nitrido-bridged RuIII, RuIV complex. The Ru–N–Ru bond angle in 2 is 170.8(2)° and the N5Ru–N–RuN5 system adopts a staggered configuration. The average Ru–N bond distances of the two metal atoms are slightly different. These parameters do not agree with the widely accepted view that most nitrido bridged ruthenium atoms have a RuNRu allene type structure. Complex 3, [(C2H4O2)2RuN]−, a by-product of the reaction, is a RuVI complex containing a triply-bonded terminal nitride with a RuN bond distance of 1.598(3) Å.