Room‐Temperature Photogeneration of Nitrosyl Linkage Isomers in Ruthenium Nitrosyl Complexes

Abstract

The conditions for the photogeneration of NO linkage isomers at room temperature are studied. By pulsed laser irradiation in the blue spectral range the long-lived Ru-ON isomer can be generated at room temperature, which is crucial for potential applications such as holography and data storage. Using static and time-resolved spectroscopy (UV/Vis and IR) we give evidence that the liftime of the Ru-(η 2 -(NO)) isomer is a decisive parameter for the formation of Ru-ON isomer at high temperature due to a two-step isomerization mechanism Ru-NO → Ru-(η 2 -(NO)) → Ru-ON. Furthermore, we report the low temperature structures for each isomer, which were revealed by photocrystallography.

Synthesis of the Ruthenium Nitrosyl Complex with Coordinated Ammonia and Pyridine at Room Temperature

“…The MS2 state serves as an intermediate in the GS ‐to‐ MS1 photoreaction. The two‐step nature of it was confirmed at room temperature and at 100 K . The MS1 state of the complex 1 was generated at 80 K with help of 445‐nm light‐emitting diode.…”

Combining photoinduced linkage isomerism and nonlinear optical properties in ruthenium nitrosyl complexes

“…IR spectroscopy is an extremely sensitive technique for detecting a bondlinkage change. The NO stretching vibration (NO) is a particularly useful fingerprint for the identification of nitrosyl linkage isomers (Mikhailov et al, 2019). Concerning the spectrum of GS, the (NO) band has a maximum at 1902 cm À1 with a shoulder at 1910 cm À1 at 10 K. Light irradiation of GS in the range 300-500 nm generates MS1, characterized by its (ON) band with a maximum at 1769 cm À1 (Fig.…”

“…Since the model with Ru-NO yields a better fit of the GS+MS1 structure and the elongation of the Ru-(NO) distance is only 0.02-0.03 Å , we can conclude that the population of the Ru-ON isomer is significantly lower than that of the Ru-NO isomer, in agreement with the spectroscopic results. For comparison, in the K 2 [RuNO(NO 2 ) 4 OH], [RuNO(py) 2 -(NO 2 ) 2 OH], [RuNO(py) 4 Cl](PF 6 ) 2 Á0.5H 2 O and [RuNO-(py) 4 F](ClO4) 2 ruthenium nitrosyl complexes, the elongation of the Ru-(NO) bond distance from GS to MS1 was 0.1 (1) Å (Fomitchev & Coppens, 1996;Cormary et al, 2009;Kostin et al, 2015;Mikhailov et al, 2019).…”

“…All other bond distances in the GS+MS1 structure are the same as in GS to within the limit of error. Since the population of the Ru-ON isomer is only 10-20%, the accuracy of the structural parameters obtained from the refinement of the structure of MS1 is limited, as discussed in the literature (Cormary et al, 2009;Kostin et al, 2015;Mikhailov et al, 2019). For example, the largest change in the bond lengths after blue-light irradiation is the elongation of the Ru-ON bond by 0.1 (1) Å , which can be unambiguously refined only in the case of high populations of the Ru-ON state.…”

“…In previous work we have shown that [RuNO-(py) 4 F](ClO 4 ) 2 exhibits the highest MS1 thermal stability and that MS1 can be photogenerated by blue light up to 230 K using a continuous-wave (CW) light source for irradiation, and even at room temperature when using pulsed laser irradiation (Kostin et al, 2018;Mikhailov et al, 2019). We also showed that the thermal stability of MS2 is essential for the roomtemperature generation of MS1, as the GS to MS1 excitation occurs via MS2 as an intermediate state (Mikhailov et al, 2019). Accordingly, the aim of the current study is to improve the thermal stability of MS1 and MS2, using fluorine as a transto-NO ligand, by the synthesis of trans-[RuNO(NH 3 ) 4 F]SiF 6 , which crystallizes in a non-centrosymmetric space group.…”