Cis–trans isomerization in the syntheses of ruthenium cyclam complexes with nitric oxide

Abstract The cis to trans isomerizations during the syntheses of trans -[Ru(NO)(OH)(cyclam)](PF 6 ) 2 , from cis -[RuCl 2 (cyclam)]Cl, and [Ru(NO)Cl(cyclam)] (PF 6 ) 2 , from cis -[RuCl 2 (dmso) 4 ], are reported. The novel trans -[Ru(NO)(OH)(cyclam)](PF 6 ) 2 complex was characterized by X-ray crystallography and vibrational infrared and nuclear magnetic resonance spectroscopies. The Ru–N–O bond angle (176.75o) and ν(NO) (1835 cm − 1 ) suggest a nitrosonium character for this hydroxo complex. The crystal and molecular structure of trans -[Ru(NO)Cl(cyclam)](ClO 4 ) 2 ·2 H 2 O is also reported. Results presented here support the cis – trans isomerization observed for the first time with ruthenium cyclam complexes.