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

The cis to trans isomerizations during the syntheses of trans-[Ru(NO)(OH)(cyclam)](PF6)2, from cis-[RuCl2(cyclam)]Cl, and [Ru(NO)Cl(cyclam)] (PF6)2, from cis-[RuCl2(dmso)4], are reported. The novel trans-[Ru(NO)(OH)(cyclam)](PF6)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)](ClO4)2·2 H2O is also reported. Results presented here support the cis–trans isomerization observed for the first time with ruthenium cyclam complexes.

Cis–trans isomerization in the syntheses of [Ru(NO)L(cyclam)] from cis-[RuCl2(cyclam)]Cl after reduction and followed by addition of nitriteFigure optionsDownload as PowerPoint slideHighlights
► Cis–trans isomerization in the syntheses of [Ru(NO)L(cyclam)] from cis complexes.
► Trans–ruthenium nitrosyl complexes with cyclam ligand synthesized from cis analogues.
► Cis–trans isomerization in the syntheses of [Ru(NO)L(cyclam)] upon addition of nitrite.
► Novel trans-[Ru(NO)(OH)(cyclam)](PF6)2 complex obtained from cis-[RuCl2(cyclam)]Cl.
► Trans-[Ru(NO)Cl(cyclam)](ClO4)2 obtained from cis-[RuCl2(dmso)4].
► Cis–trans isomerizations are supported by X-ray crystallography and other techniques.