21192-23-4Relevant articles and documents
Piacenti, F.,Bianchi, Benedetti, E.,Sbrana, G.
, p. 1389 - 1391 (1967)
Acrylic acid derivatives of group 8 metal carbonyls: A structural and kinetic study
Li, Bo,Kyran, Samuel J.,Yeung, Andrew D.,Bengali, Ashfaq A.,Darensbourg, Donald J.
, p. 5438 - 5447 (2013/06/26)
The synthesis, spectroscopic, and X-ray structural studies of acrylic acid complexes of iron and ruthenium tetracarbonyls are reported. In addition, the deprotonated η2-olefin bound acrylic acid derivative of iron as well as its alkylated species were fully characterized by X-ray crystallography. Kinetic data were determined for the replacement of acrylic acid, acrylate, and methylacrylate for the group 8 metal carbonyls by triphenylphosphine. These processes were found to be first-order in the concentration of metal complex with the rates for dissociative loss of the olefinic ligands from ruthenium being much faster than their iron analogues. However, the ruthenium derivatives afforded formation of primarily mono-phosphine metal tetracarbonyls, whereas the iron complexes led largely to trans-di-phosphine tricarbonyls. This difference in behavior was ascribed to a more stable spin crossover species 3Fe(CO)4 which undergoes rapid CO loss to afford the bis phosphine derivative. The activation enthalpies for dissociative loss of the deprotonated η2-bound acrylic acid ligand were found to be larger than their corresponding values in the protonated derivatives. For example, for dissociative loss of the protonated and deprotonated acrylic acid derivatives of iron(0) the ΔH? values determined were 28.0 ± 1.2 and 34.1 ± 1.5 kcal·mol-1, respectively. Density functional theory (DFT) computations of the bond dissociation energies (BDEs) in these acrylic acids and closely related complexes were in good agreement with enthalpies of activation for these ligand substitution reactions, supportive of a dissociative mechanism for olefin displacement. Processes related to catalytic production of acrylic acid from CO2 and ethylene are considered.
Control of the photochemistry of Ru3(CO)12 and Os3(CO)12 by variation of the solvent1
Leadbeater, Nicholas E.
, p. 211 - 216 (2007/10/03)
The synthetic potential of the photosubstitution of CO by two-electron donor ligands in M3(CO)12 [M=Ru, Os] has been investigated. When used as photolysis media, diethyl ether, ethyl acetate and acetonitrile act as photofragmentation quenchers allowing for the synthesis of photosubstitution products in high yield. UV photolysis of M3(CO)12 with added triphenylphosphine in these photolysis media leads to M3(CO)12-n(PPh3)n (n=1, 2 or 3). Prolonged photolysis with added tricyclohexylphosphine generates the highly sterically crowded complex M3(CO)9(PCy3)3. Photolysis with thiols, RSH (R=Et, Ph), leads to the thiolato complexes HM3(μ-SR)(CO)10, prolonged photolysis of which generates the corresponding sulphido cluster M3(μ3-S)(CO)10. Photolysis of M3(CO)12 in acetonitrile with no added ligand results in the generation of M3(CO)12-n(MeCN)n (n=1 or 2). This offers a route to these complexes without the need for the use of oxidising agents such as trimethylamine-N-oxide. Photolysis of an ethene-saturated diethyl ether or ethyl acetate solution of M3(CO)12 leads to no net photoreaction in the case of ruthenium, whereas, for osmium, the olefin complex Os(CO)4(η2-C2H4) is formed. This highlights the difference in the photosubstitution mechanism for Ru3(CO)12 and Os3(CO)12.
