Diruthenium acetylide compounds with masked diazonium capping groups

Reported in this contribution are the synthesis and characterization of the following diruthenium arylacetylide compounds containing dialkyl–triazene capping groups: Ru2(ap)4-(Ctriple bond; length of mdashC-4-C6H4–N3Et2) (2), Ru2(ap)4-(Ctriple bond; length of mdashC-3-C6H4–N3Et2) (3), and trans-[Ru2(DMBA)4](-Ctriple bond; length of mdashC-4-C6H4–N3Et2)2 (4), where ap is 2-anilinopyridinate and DMBA is N,N-dimethylbenzamidinate. Compounds 2/3 were prepared by the addition of diethylamine to the diazonium intermediate, Ru2(ap)4-(Ctriple bond; length of mdashC-3/4-C6H4–N2+), under basic conditions, and compound 4 was synthesized from Ru2(DMBA)4(NO3)2 and HCtriple bond; length of mdashC-4-C6H4–N3Et2 under weakly basic conditions. An X-ray study of 4 provided a unique structural example of inorganic compounds bearing dialkyl–triazene functional groups, and revealed a minimal alteration in the first coordination sphere of Ru2 core upon the attachment of dialkyl–triazene caps. Similar to previously reported diruthenium compounds, 2, 3 and 4 display rich redox chemistry with a reversible diruthenium oxidation and reduction, as well as an oxidation of the triazene group to a radical.