title: Comparison of thermodynamic and kinetic aspects of oxidative addition of PhE-EPh (E = S, Se, Te) to Mo(CO)3(PR3)2, W(CO)3(PR3)2, and Mo(N[tBu]Ar)3 complexes. The role of oxidation state and ancillary ligands in metal complex induced chalcogenyl radical generation.
abstract: Enthalpies of oxidative addition of PhE-EPh (E = S, Se, Te) to the M(0) complexes M(PiPr3)2(CO)3 (M = Mo, W) to form stable complexes M(*EPh)(PiPr3)2(CO)3 are reported and compared to analogous data for addition to the Mo(III) complexes Mo(N[tBu]Ar)3 (Ar = 3,5-C6H3Me2) to form diamagnetic Mo(IV) phenyl chalcogenide complexes Mo(N[tBu]Ar)3(EPh). Reactions are increasingly exothermic based on metal complex, Mo(PiPr3)2(CO)3 < W(PiPr3)2(CO)3 < Mo(N[tBu]Ar)3, and in terms of chalcogenide, PhTe-TePh < PhSe-SePh < PhS-SPh. These data are used to calculate LnM-EPh bond strengths, which are used to estimate the energetics of production of a free *EPh radical when a dichalcogenide interacts with a specific metal complex. To test these data, reactions of Mo(N[tBu]Ar)3 and Mo(PiPr3)2(CO)3 with PhSe-SePh were studied by stopped-flow kinetics. First- and second-order dependence on metal ion concentration was determined for these two complexes, respectively, in keeping with predictions based on thermochemical data. ESR data are reported for the full set of bound chalcogenyl radical complexes (PhE*)M(PiPr3)2(CO)3; g values increase on going from S to Se, to Te, and from Mo to W. Calculations of electron densities of the SOMO show increasing electron density on the chalcogen atom on going from S to Se to Te. The crystal structure of W(*TePh)(PiPr3)2(CO)3 is reported.
authors.affiliation: University of Miami, Coral Gables, Florida 33124, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: McDonough
authors.forename: John J
authors.initials: JJ
authors.lastname: Weir
authors.forename: Kengkaj
authors.initials: K
authors.lastname: Sukcharoenphon
authors.forename: Carl D
authors.initials: CD
authors.lastname: Hoff
authors.forename: Olga P
authors.initials: OP
authors.lastname: Kryatova
authors.forename: Elena V
authors.initials: EV
authors.lastname: Rybak-Akimova
authors.forename: Brian L
authors.initials: BL
authors.lastname: Scott
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Kubas
authors.forename: Arjun
authors.initials: A
authors.lastname: Mendiratta
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Cummins
mesh_terms: D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D013816:Thermodynamics
chemical_list: D008024:Ligands; D008670:Metals