title: Photocrystallography and IR spectroscopy of light-induced linkage NO isomers in [RuBr(NO)2(PCyp3)2]BF4.
abstract: One single photo-induced linkage NO isomer (PLI) is detected and characterized in the dinitrosyl pentacoordinated compound [RuBr(NO)2(PCyp3)2]BF4 by a combination of photocrystallographic and IR analysis. In the ground state, the molecule adopts a trigonal-bipyramidal structure with the two NO ligands almost linear with angles Ru-N1-O1 = 168.92 (16), Ru-N2-O2 = 166.64 (16)°, and exactly equal distances of Ru-N = 1.7838 (17) and O-N = 1.158 (2) Å. After light irradiation of 405 nm at T = 10 K, the angle of Ru-N2-O2 changes to 114.2 (6)° by rotation of the O atom towards the Br ligand with increased distances of Ru-N2 = 1.992 (6) and N2-O2 = 1.184 (8) Å, forming a bent κN bonded configuration. Using IR spectroscopy, the optimal wavelength and maximum population of 39 (1)% of the PLI is determined. In the ground state (GS), the two symmetric νs(NO) and asymmetric νas(NO) vibrations are measured at 1820 and 1778 cm(-1), respectively. Upon photo-irradiation, the detection of only one new vibrational ν(NO) stretching band at 1655 cm(-1), assigned to the antisymmetric coupled vibration mode and shifted to lower wavenumbers by -123 cm(-1), supports the photocrystallographic result. These experimental results are supported by additional DFT calculations, which reproduce the structural parameters and vibrational properties of both the ground state and the photo-induced linkage isomer well. Especially the experimentally characterized molecular structure of the PLI state corresponds to an energy minimum in the calculations; the stabilization of the bent κN bonded configuration of the PLI state originates from specific intramolecular orbital overlap.
authors.affiliation: Université de Lorraine, CRM2, UMR 7036, F-54506 Vandoeuvre-les-Nancy, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Casaretto
authors.affiliation: Université de Lorraine, CRM2, UMR 7036, F-54506 Vandoeuvre-les-Nancy, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Pillet
authors.affiliation: Université de Lorraine, CRM2, UMR 7036, F-54506 Vandoeuvre-les-Nancy, France.
authors.forename: El Eulmi
authors.initials: el E
authors.lastname: Bendeif
authors.affiliation: Université de Lorraine, CRM2, UMR 7036, F-54506 Vandoeuvre-les-Nancy, France.
authors.forename: Dominik
authors.initials: D
authors.lastname: Schaniel
authors.affiliation: Department Chemie der Ludwig-Maximilians-Universität, Butenandtstraße 5-13, 81377 Munich, Germany.
authors.forename: Anna K E
authors.initials: AK
authors.lastname: Gallien
authors.affiliation: Department Chemie der Ludwig-Maximilians-Universität, Butenandtstraße 5-13, 81377 Munich, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Klüfers
authors.affiliation: Institut für Strukturphysik, TU Dresden, Zellescher Weg 16, Dresden, Germany.
authors.forename: Theo
authors.initials: T
authors.lastname: Woike
keywords: IR spectra; dinitrosyl compounds; light-induced isomerism; photocrystallography