Photogeneration of metastable side-on N2 linkage isomers in [Ru(NH3)5N2]Cl2, [Ru(NH3)5N2]Br2 and [Os(NH3)5N2]Cl2

Abstract

Photogeneration of side-on N2 linkage isomers in [Ru(NH3)5N2]2+ and [Os(NH3)5N2]2+ is achieved by irradiation with lambda = 325 nm of powder samples at T = 80 K and detected by the downshift of the nu(N-N) vibration and by the heat release at elevated temperature due to the back switching of the side-on configuration to the ground state. The concentration of the transferred molecules is evaluated by the decrease of the area of the nu(N-N) or 2nu(N-N) vibrational bands. All characteristic changes between the linear Ru-N-N and side-on configuration are predicted by DFT calculations: the structure of the anion, shifts of the vibrations, electronic excitation energy, energetic position and sequence of the electronic orbitals, the potentials of the ground and relaxed metastable state with the activation energy, saddle points and energetic position of the minimum.

Computational Investigations of the Chemical Mechanism of the Enzyme Nitrogenase

“…Other assessments of DMol accuracy have examined 1) the electron affinities of atoms and molecules, 2) the enthalpies of formation for small (<100 electrons) molecular and atomic species, 3) the structures of metal‐sulfide clusters, 4) photo‐induced conversion of [Os(NH 3 ) 5 (η 1 ‐N 2 ] 2+ to [Os(NH 3 ) 5 (η 2 ‐N 2 ] 2+ (i.e., end‐on to side‐on bonding of N 2 ), 5) the geometry and vibrational frequencies of [(NH 3 ) 5 Ru(pyrazine)Ru(NH 3 ) 5 ] 4+, 5+, 6+ , 6) the lattice parameters of molecular crystals with weak intermolecular interactions, 7) the experimental interatomic potentials for rare gases, 8) protonation reactions involving hydrogen bonding…”

Reversible photoswitching between nitrito-N and nitrito-O isomers in trans-[Ru(py)4(NO2)2]

“…6,7 Linkage isomers of various ligands Z have been generated in [ML y L t Z] n complexes by direct chemical reactions, 8 by variation of temperature and through redox-reactions in solutions, [9][10][11][12] through electrochemical oxidation, [13][14][15][16] by pH, 17 and especially through light-irradiation. 3,[18][19][20] Here M is the central atom, usually a transition metal, L y are equatorial ligands with coordination number y, and L t is the ligand trans to the photoswitchable ligand Z (e.g. Z = N 2 , NO, SO, SO 2 , NO 2 ).…”

Structural analysis of the coordination of dinitrogen to transition metal complexes

“…Although all structures have been structurally characterized, it was proposed for the conversion mechanism in a rhenium complex between both end-on forms at room temperature, having an energy barrier of $ 93 kJ mol À1 (Cusanelli & Sutton, 1996). More recently, crystallographic (Fomitchev et al, 2000) and spectroscopic (Schaniel et al, 2008) studies on the photo-induced metastable form of [M(NH 3 ) 5 (N 2 )] 2+ (M = Ru, Os) have been reported. All studies confirm that side-on coordination in mononuclear complexes is always higher in energy than end-on.…”