New nitrosyl ruthenium complex [RuCl(NO)(dcype)(bipy)](PF6)2: Synthesis, electrochemistry, NMR and ESI-MS/MS studies

Reactivity of cis-[RuCl2(dcype)(bipy)] (dcype = 1,2-bis(dicyclohexylphosphino)ethane and bipy = 2,2′-bipyridine) with nitric oxide afforded the new dicationic complex [RuCl(NO)(dcype)(bipy)]2+. The complex isolated as PF6- salt was characterized by spectroscopical, electrochemical and ESI-MS/MS techniques as well as elemental analysis. Surprisingly the analysis of 31P{1H} and 15N{1H} NMR spectra of the [RuCl(15NO)(dcype)(bipy)]2+ complex reveal that the NO is in trans position to one of the P atom of dcype. The IR spectrum showed the presence of υNO in 1889 cm−1 with is in agreement with the presence of NO+, but based on 31P{1H} NMR analysis the nitrosyl do not behave as a strong π-acceptor since little (or none) trans structural effect was observed on 31P chemical shift compared to the precursor cis-[RuCl2(dcype)(bipy)]. In the ESI-MS analysis, we just have detected the intact nitrosyl complex in CH2Cl2 solutions, but in MeOH solutions, the ion [M−NO]+ was detected, indicating the lability of M−NO bond. MSn spectra with variable collision energy indicate a fragmentation pathway with radical bi-cyclohexyl-phosphine and two cyclohexene losses.

Graphical abstractA new P−P/N−N containing Ru−NO complex was synthesized from cis-[RuCl2(dcype)(bipy)]. The complex was characterized by NMR (31P, 1H and 15N), ESI-MS, elemental analysis and cyclic voltammetry.Figure optionsDownload full-size imageDownload as PowerPoint slide