Evidence for a common Ru(P)(NO)₂ intermediate in photochemical and synthesis pathways involving Ru(TmTP)(NO)(ONO) and excess nitric oxide

Abstract

Optical and IR spectra of the intermediate formed from the reaction of Ru(CO)(TmTP) with NO are compared with transient UV–VIS and FTIR spectra of photochemical intermediates formed from the photolysis and recovery of Ru(TmTP)(NO)(ONO) in the presence of NO; comparison reveals that the two pathways share a common intermediate, which IR spectral properties suggest to be trans-Ru(TmTP)(NO)₂.

References

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13. A referee has suggested another structure for X, namely Ru(P)-(N(O)NO), formed by reaction of NO with the coordinated NO of Ru(P)(NO). However, this formulation for X would be predicted to give products for the isotopic exchange experiments where Ru(TmTP)-(NO)(ONO) was photolyzed in the presence of ¹⁵N¹⁸O different from those observed (ref. 11). Those products can indeed be explained on the basis of formation of a dinitrosyl Ru(P)(NO)₂ intermediate. Another argument against this formulation would be that –N(O)NO ligand would also be expected to give two strong ν_NO bands yet only one new band was detected in the 1500–2300 cm^–1 region. No new bands were seen in the 1000–1500 cm ^–1 region either; however, in that region there are several windows possibly obscured by solvent interference.
14. Based on the estimated absorption coefficients for N₂O, the yield of nitrous oxide in the second stage of the reaction was ca. 65% that of 1, but the small intensity of the signal at 2215 cm ^–1 as well as possible pathways for N₂O loss add to the uncertainty of this value.