Studies of κ- and κ-tripyridylamine complexes of ruthenium and π-stacking by pyridyls.

The reaction of tris(pyridin-2-yl)amine with [CyRuCl] (Cy = p-isopropyltoluene or cymene) in refluxing diglyme led to the formation of cis-[RuCl{κ-(2-py)N}]·CHCl (1a) after recrystallization from chloroform/pentane, or cis-dichloridobis[tris(pyridin-2-yl)amine-κN,N']ruthenium(II) dichloromethane disolvate, [RuCl(CHN)]·2CHCl or cis-[RuCl{κ-(2-py)N}]·2CHCl (1b). Treatment of 1a with one equivalent of silver(I) hexafluoridoantimonate in dichloromethane gave [RuCl{κ-(2-py)N}{κ-(2-py)N}][SbF]·CHCl (2a). Crystallization of 2a from chloroform provided chlorido[tris(pyridin-2-yl)amine-κN,N'][tris(pyridin-2-yl)amine-κN,N',N'']ruthenium(II) hexafluoridoantimonate chloroform monosolvate, [RuCl(CHN)][SbF]·CHCl or [RuCl{κ-(2-py)N}{κ-(2-py)N}][SbF]·CHCl (2b). Complex 2a reacted with a further equivalent of silver(I) hexafluoridoantimonate to give [Ru{κ-(2-py)N}][SbF] (3). The reaction of (2-py)N with [CyRuCl] in dichloromethane followed by treatment with excess sodium hexafluoridoantimonate gave the known complex [CyRuCl{κ-(2-py)N}][SbF] (4). Complex 2 is a rare example of a complex containing both κ- and κ-(2-py)N. Intramolecular π-stacking interactions determine the orientation of the free pyridyl in the κ complexes. An interesting encapsulation of methylene chloride hydrogen-bonded tetramers was noted in one case.