[Ru(py)₄Cl(NO)](PF₆)₂·0.5H₂O: a model system for structural determination and ab initio calculations of photo-induced linkage NO isomers

Abstract

Structure analysis of ground state (GS) and two light-induced (SI and SII) metastable linkage NO isomers of [Ru(py)4Cl(NO)](PF6)2.0.5H2O is presented. Illumination of the crystal by a laser with lambda = 473 nm at T = 80 K transfers around 92% of the NO ligands from Ru-N-O into the isomeric configuration Ru-O-N (SI). A subsequent irradiation with lambda = 980 nm generates about 48% of the side-on configuration Ru<(N)(O) (SII). Heating to temperatures above 200 K or irradiation with light in the red spectral range transfers both metastable isomers reversibly back to the GS. Photodifference maps clearly show the N-O configurations for both isomers and they could be used to find a proper starting model for subsequent refinements. Both metastable isomers have slightly but significantly different cell parameters with respect to GS. The main structural changes besides the Ru-O-N and RU<(N)(O) linkage are shortenings of the trans Ru-Cl bonds and the equatorial Ru-N bonds. The experimental results are compared with solid-state calculations based on density functional theory (DFT), which reproduce the observed structures with high accuracy concerning bond lengths and angles. The problem of how the different occupancies of SI and GS could affect refinement results was solved by a simulation procedure using the DFT data as starting values.

Effects of the reaction cavity on metastable optical excitation in ruthenium-sulfur dioxide complexes

“…In general, as for NO complexes, the photoexcited state population will depend on anisotropy introduced during the irradiation process, such as the polarization and orientation of the light. 15,22 However, this effect is unlikely to be significant in this experiment due to the use of an unpolarized source and rotation about during irradiation and because the two Ru-SO 2 moeities are almost exactly antiparallel to one another ͑Ru-S vectors 175.0°apart, RuSO 2 planes 13.5°apart͒.…”

Solid‐State Interconversions: Unique 100 % Reversible Transformations between the Ground and Metastable States in Single‐Crystals of a Series of Nickel(II) Nitro Complexes

“…A rare exception is the 92 % single-crystal conversion of [Ru(py) 4 Cl(NO)][PF 6 ] 2 ⋅ 0.5 H 2 O from a η 1 -N O nitrosyl to a metastable η 1 -O N nitrosyl upon irradiation reported by Woike,[7n] however, excitation levels around 50 % are typical. If metastable linkage isomers are to find applications in devices[9] then reversible 100 % interconversion between isomers is essential.…”

“…These include the introduction of unacceptable levels of strain within a crystal resulting from the photoinduced molecular rearrangement, that intermolecular interactions present within the crystal disfavour the molecular rearrangement,[10] or simply that the spectral overlap of the absorption bands of the ground state and the metastable state at the wavelength of irradiation is sufficient to set up an equilibrium between the two states so that complete conversion will not occur. [7n]…”

cis-Chloridobis(4,4′-dimethyl-2,2′-bipyridine)nitrosylruthenium(II) bis(hexafluorophosphate)

“…Ruthenium nitrosyl complexes can either induce photochromism (Schaniel et al, 2007b) or NO photorelease (Rose & Mascharak, 2008). In the first case, photoisomerization along the rutheniumnitrosyl bond (Ru-NO/Ru-ON) is observed in the solid state when the compounds are irradiated in the blue region (Schaniel et al, 2007a;Cormary et al, 2009Cormary et al, , 2012. It offers technological applications as optical high-capacity storage devices (Imlau et al, 1999).…”