Studies of κ 2 - and κ 3 -tripyridylamine complexes of ruthenium and π-stacking by pyridyls

The reaction of tris(pyridin-2-yl)amine with [CyRuCl 2 ] 2 (Cy = p -isopropyltoluene or cymene) in refluxing diglyme led to the formation of cis -[RuCl 2 {κ 2 -(2-py) 3 N} 2 ]·CHCl 3 ( 1a ) after recrystallization from chloroform/pentane, or cis -dichloridobis[tris(pyridin-2-yl)amine-κ 2 N , N ′]ruthenium(II) dichloromethane disolvate, [RuCl 2 (C 15 H 12 N 4 ) 2 ]·2CH 2 Cl 2 or cis -[RuCl 2 {κ 2 -(2-py) 3 N} 2 ]·2CH 2 Cl 2 ( 1b ). Treatment of 1a with one equivalent of silver(I) hexafluoridoantimonate in dichloromethane gave [RuCl{κ 2 -(2-py) 3 N}{κ 3 -(2-py) 3 N}][SbF 6 ]·CH 2 Cl 2 ( 2a ). Crystallization of 2a from chloroform provided chlorido[tris(pyridin-2-yl)amine-κ 2 N , N ′][tris(pyridin-2-yl)amine-κ 3 N , N ′, N ′′]ruthenium(II) hexafluoridoantimonate chloroform monosolvate, [RuCl(C 15 H 12 N 4 ) 2 ][SbF 6 ]·CHCl 3 or [RuCl{κ 2 -(2-py) 3 N}{κ 3 -(2-py) 3 N}][SbF 6 ]·CHCl 3 ( 2b ). Complex 2a reacted with a further equivalent of silver(I) hexafluoridoantimonate to give [Ru{κ 3 -(2-py) 3 N} 2 ][SbF 6 ] 2 ( 3 ). The reaction of (2-py) 3 N with [CyRuCl 2 ] 2 in dichloromethane followed by treatment with excess sodium hexafluoridoantimonate gave the known complex [CyRuCl{κ 2 -(2-py) 3 N}][SbF 6 ] ( 4 ). Complex 2 is a rare example of a complex containing both κ 2 - and κ 3 -(2-py) 3 N. Intramolecular π-stacking interactions determine the orientation of the free pyridyl in the κ 2 complexes. An interesting encapsulation of methylene chloride hydrogen-bonded tetramers was noted in one case.