Side-on bound complexes of phenyl- and methyl-diazene

Treatment of trans-[FeCl2(dmpe)(2)] with phenylhydrazine and 1 equiv of base afforded the side-on bound phenylhydrazido complex cis-[Fe(eta(2)-NH2NPh)(dmpe)(2)](+). Further deprotonation of the phenylhydrazido complex afforded the side-on bound phenyldiazene complex cis-[Fe(eta(2)-HN=NPh)(dmpe)(2)] as a mixture of diastereomers. Treatment of cis-[RuCl2(dmpe)(2)] with phenylhydrazine or methylhydrazine afforded the end-on bound phenylhydrazine or methylhydrazine complexes cis-[RuCl(eta(1)-NH2NHR)(dmpe)(2)](+) (R = Ph, Me). Treatment of the substituted hydrazine complexes with base afforded the side-on bound phenylhydrazido complex cis-[Ru(eta(2)-NH2NPh)(dmpe)(2)](+) as well as the phenyldiazene and methyldiazene complexes cis-[Ru(eta(2)-HN=NR)(dmpe)(2)] (R = Ph, Me). cis-[RuCl(eta(1)-NH2NHR)(dmpe)(2)](+) (R = Ph, Me), cis-[M(eta(2)-NH2NPh)(dmpe)(2)](+) (M = Fe, Ru) and cis-[Ru(eta(2)-HN=NPh)(dmpe)(2)] were characterized structurally by X-ray crystallography. cis-[Ru(eta(2)-HN=NPh)(dmpe)(2)] is the first side-on bound phenyldiazene complex to be structurally characterized. In the structure of cis-[Ru(eta(2)-HN=NPh)(dmpe)(2)], the geometry of the coordinated diazene fragment is significantly nonplanar (CNNH angle 137 degrees) suggesting that the complex is probably better described as a Ru(II) metallodiaziridine than a Ru(0) diazene pi-complex.