FTIR and DFT-D investigation of the structure of ruthenium pentacarbonyl in small alcohol solvents

FTIR investigation of the equilibrium structure of osmium pentacarbonyl in alcohol solvents

“…A greater degree of fluxionality should reduce the degree of destabilization of the MPC during complexation and consequently lower the Gibbs free energy of solvent complexation. In past work, DFT analysis of IPC and RPC solvent complexes has demonstrated that the interaction energy between the MPC and solvent molecule is better predicted when dispersion forces are included [26]. The experimental data presented in this letter may help serve as a benchmark for recently developed dispersion training sets for heavier elements such as osmium [46].…”

“…Formation of the hexacoordinated MPC-solvent complex causes a distortion of the D 3h symmetry of the bare MPC, which in turn renders the symmetric 1 mode IR active [22,24,26]. The intensity of 1 IR absorption can therefore be related to the complex population in solution.…”

“…It has been shown that in arene, alcohol and amine solvent media, 60-90% of iron pentacarbonyl (IPC) molecules may undergo structural and electronic deformations and weakly hexacoordinate with a single solvent molecule, forming an Fe(CO) 5 -solvent complex [21][22][23][24]. Similar studies have shown that Ru(CO) 5 interacts with a single solvent molecule via a nearly identical mechanism, albeit more strongly and to a greater extent than IPC [25,26]. The theoretically most stable geometry of gas-phase IPC and its Group 8 analogs, ruthenium pentacarbonyl (RPC) and osmium pentacarbonyl (OPC) is trigonal bipyramidal (D 3h ) [27][28][29][30][31].…”

“…In order to account for the low intensity of the 1 mode relative to the 6 and 10 modes, two samples with different concentrations and path lengths were measured, as in a previously published work [26]. The OPC solutions were prepared quantitatively by mass in concentrations ranging from 0.1-0.2 M for resolving the 1 mode and ∼0.01 M for resolving 6 and 10 .…”

“…2-butanol and 1-hexanol were obtained from Sigma-Aldrich and used as received. The synthesis of OPC was performed nearly identically to RPC [26], except at a higher temperature of 280 • C. Solutions of TODC were made in cyclohexane and alcohol solvents for the purpose of reference.…”