Kinetic and thermodynamic stabilities of the geometric isomers of dicarbonyldichlorobis(tertiary phosphine)ruthenium and carbonyldichlorotris(tertiary phosphine)ruthenium complexes

Abstract

From the observed conditions hkl, h + k = 2n, and hOl, I = 2n, the two possible space groups are Cc (No. 9) and C2/c (No. 15). Solution of the structure was accomplished by Patterson methods. Both the anion and the cation can be located on crystallographic 2-fold axes. Thus C2/c is the space group of choice.An absorption correction was applied.30 Four low-angle reflections appeared to be affected by extinction and were removed from the set of reflections used in refinement. The lattice molecule of chloroform was disordered and was given an occupancy of 0.5 on the basis of Fourier peak heights. It was refined with inter-chlorine and chlorine-carbon distance constraints by the method of additional observational eq~ations.~ Another site in the lattice is occupied by two partial molecules of dichloromethane that are rotated approximately 90' with respect to their chlorine-chlorine vectors. They were refined with fixed Us of 0.08 .AZ and variable occupancies that converged at 0.309 (9) and 0.195 (9), respectively. Hydrogen atoms were included in the structure factor calcualtion at idealized positions by using a model in which the hydrogen atoms ride on the bonded carbon and C-H is 0.96 A. In the final cycles (30) XAW produces an absorption tensor from an expression relating F, and F,: Moezzi, B. Ph.D. Thesis, University of California, Davis, CA, 1988.of refinement all non-hydrogen atoms were assigned anisotropic thermal parameters except the carbon of chloroform and the chlorines of dichloromethane (the latter carbon atom was not located). In the final difference map the largest feature was 2.1 e A-' in height, in the vicinity of one of the chloroform molecules. X-ray Structure Determination and Refmemeat for 3. Orange blocks of Ru(dpma),Cl, were obtained by diffusion of methanol into a dichloromethane solution of the complex. Data collection, treatment, and refinement followed by the procedures outlined for 2. A value of 0.81 e A" was found for the largest feature in the final difference map. This was 0.69 A away from C(19). Acknowledgment. We thank the National Science Foundation (Grant CHE 8519557) for financial support and Dr. J. de Ropp of the UCD NMR facility for assistance with the NMR experiments. Supplementary Material Available:Listings of all bond lengths, bond angles, hydrogen atom positions, anisotropic thermal parameters, and data collection parameters (10 pages); listings of observed and calculated structure factors (58 pages). Ordering information is given on any current masthead page.Contribution from the A series of ruthenium(I1) complexes of the type R u C I~( C O )~P~ (P = BzljP, PhjP, PhzMeP, PhMezP, Me3P) have been prepared and characterized by elemental analyses, physical properties, infrared spectroscopy, UV-visible spectroscopy, and IH, 13C(1H) and ,IP( IHJ NMR spectroscopy. The first-formed complex, with all ligand pairs trans (ttt), thermally isomerizes in solution to produce the isomer with all ligand pairs cis (ccc). This ccc isomer further isomerizes in solution to produce the thermodynam...

On the behaviour of Ru(I) and Ru(II) carbonyl acetates in the presence of H2 and/or acetic acid and their role in the catalytic hydrogenation of acetic acid

“…After 48 h traces of (3) were still present. A quantitative conversion of (3) into (11) was reached after 70 h. No other transformations were observed increasing the temperature up to 120°C. At this temperature part of the acetic acid was present in vapour phase decreasing its concentration in solution.…”

“…However, the IR spectrum of the same residue in a n-heptane/acetic acid solution showed the presence of (11) as the sole complex in solution because the absorptions of (2) in acetic acid are shifted and overwhelmed by those of (11).…”

“…As a consequence the reaction was reversed and (3) returned to be the main complex present in the solution (Scheme 2). A further increase of temperature (150°C) reduced further the concentration of acetic acid in solution and the amount of (11).…”

“…The process is reversible because when the vessel was cooled to room temperature and the concentration of acetic acid restored to its initial value, the amount of (11) increases: after 48 h (11) was the sole ruthenium complex present in solution.…”

“…After an hour at room temperature a singlet at 43.5 ppm (11.7%) attributable to (11) and a singlet at 17.2 ppm (1.2%) due to (2) were present in the 31 P NMR spectrum. Complex (2) was not easily identified in the IR spectrum performed in a C 6 D 6 /acetic acid solution when (11) was the main ruthenium complex because the absorptions of (2) in the presence of acetic acid are overwhelmed by those of (11). However, if the acetic acid was removed and the residue dissolved in n-pentane, the presence of (11) and (2) might be easily evidenced (see above).…”