title: Structural influence on the photochromic response of a series of ruthenium mononitrosyl complexes.
abstract: In mononitrosyl complexes of transition metals two long-lived metastable states corresponding to linkage isomers of the nitrosyl ligand can be induced by irradiation with appropriate wavelengths. Upon irradiation, the N-bound nitrosyl ligand (ground state, GS) turns into two different conformations: isonitrosyl O bound for the metastable state 1 (MS1) and a side-on nitrosyl conformation for the metastable state 2 (MS2). Structural and spectroscopic investigations on [RuCl(NO)py(4)](PF(6))(2)·1/2H(2)O (py = pyridine) reveal a nearly 100% conversion from GS to MS1. In order to identify the factors which lead to this outstanding photochromic response we study in this work the influence of counteranions, trans ligands to the NO and equatorial ligands on the conversion efficiency: [RuX(NO)py(4)]Y(2)·nH(2)O (X = Cl and Y = PF(6)(-) (1), BF(4)(-) (2), Br(-)(3), Cl(-) (4); X = Br and Y = PF(6)(-) (5), BF(4)(-) (6), Br(-)(7)) and [RuCl(NO)bpy(2)](PF(6))(2) (8), [RuCl(2)(NO)tpy](PF(6)) (9), and [Ru(H(2)O)(NO)bpy(2)](PF(6))(3) (10) (bpy = 2,2'-bipyridine; tpy = 2,2':6',2"-terpyridine). Structural and infrared spectroscopic investigations show that the shorter the distance between the counterion and the NO ligand the higher the population of the photoinduced metastable linkage isomers. DFT calculations have been performed to confirm the influence of the counterions. Additionally, we found that the lower the donating character of the ligand trans to NO the higher the photoconversion yield.
authors: Laboratoire de Chimie de Coordination, CNRS, 205 Route de Narbonne, F-31077 Toulouse, France.
authors: Benoit
authors: B
authors: Cormary
authors: Sonia
authors: S
authors: Ladeira
authors: Kane
authors: K
authors: Jacob
authors: Pascal G
authors: PG
authors: Lacroix
authors: Theo
authors: T
authors: Woike
authors: Dominik
authors: D
authors: Schaniel
authors: Isabelle
authors: I
authors: Malfant
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009603:Nitroso Compounds / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D055668:Photochemical Processes; D011789:Quantum Theory; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D009603:Nitroso Compounds; D009942:Organometallic Compounds; D012428:Ruthenium