title: Mechanism of CO displacement from an unusually labile rhenium complex: an experimental and theoretical investigation.
abstract: The displacement of a CO ligand from an unusually labile rhenium carbonyl complex containing a bidentate carboxyaldehyde pyrrolyl ligand by PPh(3) and pyridine has been investigated. The reaction is found to proceed by an associative, preequilibrium mechanism. Theoretical calculations support the experimental data and provide a complete energetic profile for the reaction. While the Re-CO bond is found to be intrinsically weak in these complexes, it is postulated that the unusual lability of this species is due to the presence of a weak aldehyde Re-O link that can easily dissociate to open a coordination site on the metal center and accommodate an incoming ligand prior to CO loss. The resulting intermediate complex has been identified by IR spectroscopy. The presence of the hemilabile pyrrolyl ligand provides a lower-energy reaction channel for the release of CO and may be of relevance in the design of CO-releasing molecules.
authors.affiliation: Department of Chemistry, Texas A&M University at Qatar, Doha, Qatar.
authors.forename: Sohail
authors.initials: S
authors.lastname: Muhammad
authors.forename: Veeranna
authors.initials: V
authors.lastname: Yempally
authors.forename: Muhammad
authors.initials: M
authors.lastname: Anas
authors.forename: Salvador
authors.initials: S
authors.lastname: Moncho
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Kyran
authors.forename: Edward N
authors.initials: EN
authors.lastname: Brothers
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Darensbourg
authors.forename: Ashfaq A
authors.initials: AA
authors.lastname: Bengali
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D012211:Rhenium / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D009942:Organometallic Compounds; D012211:Rhenium; D002248:Carbon Monoxide