DFT study of metastable linkage isomers of six-coordinate ruthenium nitrosyl complexes

Abstract

The linkage isomers of the [M(NO)(CN) 5 ] 2-(M ¼ Fe, Ru, Os), [Ru(NO)Cl 5 ] 2-, trans-[Ru(NO)(NH 3 ) 4 (L)] qþ (L ¼ NH 3 , H 2 O, nicotinamide, imidazole, pyridine, pyrazine, NO 2 -, OH -, Cl -), and trans-[Ru(NO)L 4 (OH)] q (L ¼ pyridine, NO 2 -) ions are studied by density functional theory. DFT calculations show that the electronic ground-state potential surface of these nitrosyl complexes has the local minima corresponding to h 2 -NO and h 1 -O linkage isomers, of which the former is characterized by lower energy. The stationary points on the ground state potential energy surface along the GS ! MS2 ! MS1 path for the [M(NO)(CN) 5 ] 2-(M ¼ Fe, Ru, Os) and [Ru(NO)Cl 5 ] 2-complexes were found. The calculations of infrared spectra of linkage isomers [Ru(NO)Cl 5 ] 2-and [Ru(NO)(CN) 5 ] 2-are carried out. The analysis of quantum chemical bond orders indicates a noticeable delocalization of p-electron density along the L trans --M--NO axis and a possibility of direct interactions between NO and equatorial ligands in the structures with the bent {MNO} group.

Local force constants and charges of the nitrosyl ligand in photoinduced NO linkage isomers in a prototypical ruthenium nitrosyl complex

“…But for MS1 this argument no longer holds, since the charge on the NO ligand is reduced by 0.07e with respect to GS and the change in bond length amounts to only 0.002 Å. Already Sizova and coworkers 30 discussed this discrepancy between the calculated and experimental results for the vibrational frequencies, which occur especially for MS1. They investigated the influence of the environment by applying a polarizable continuum model Table 7 Experimental (T = 10 K) and DFT calculated vibrations in MS1, differences D(Iso) between isotopes and D( 14 N) between measured/calculated 14 (PCM), which nevertheless did not resolve the issue for MS1.…”

“…In such a simple picture, the contribution of the coupling between ñ(RuN) and ñ(NO) to the experimentally observed values is neglected. As a matter of fact, Sizova et al 30 indicated the contributions of the internal coordinates to the NO and RuNO vibrations for the [RuCl 5 NO] 2À complex, which amounts up to 11% of ñ(RuN) to 89% ñ(NO) in GS using a valence force model, but without proceeding to a detailed analysis including further calculations of local force constants. Such a complete decoupling for the solid state by the transformation of all vibrations into a pure two-atomic behavior can be obtained by using the local vibrational mode theory formalism.…”

“…In the framework of this fundamental discussion we present a detailed experimental and theoretical study of the PLI in K 2 [RuCl 5 NO], which already earlier has served as a prototypical {MNO} 6 complex for DFT calculations. 29,30 Starting from an accurate single-crystal structure determination of GS we use infrared spectroscopy, including 15 N isotope substitution, to unambiguously identify the n(RuN) and n(NO) stretching and d(RuNO) deformation vibrations for GS, MS1 and MS2. A solidstate DFT calculation is performed and its quality is assessed by comparison with the experimental structural, infrared as well as NMR data of the GS.…”