title: Seeking a mechanistic analogue of the water-gas shift reaction: carboxamido ligand formation and isocyanate elimination from complexes containing the Tp'PtMe fragment.
abstract: A series of stable, isolable Tp'Pt(IV) carboxamido complexes of the type Tp'PtMe(2)(C(O)NHR) (R = Et, (n)Pr, (i)Pr, (t)Bu, Bn, Ph) has been synthesized by addition of amide nucleophiles to the carbonyl ligand in Tp'Pt(Me)(CO) followed by trapping of the Pt(II) intermediate with methyl iodide as the methylating reagent. These compounds mimic elusive intermediates resulting from hydroxide addition to platinum-bound CO in the Water-Gas Shift Reaction (WGSR). Seeking parallels to WGSR chemistry, we find that deprotonation of the carboxamido NH initiates elimination and the isocyanate-derived products form; the resulting platinum fragment can be protonated to reoxidize the metal center and generate Tp'PtMe(2)H, the synthetic precursor to Tp'Pt(Me)(CO). Mechanistic studies on the formation of and elimination from Tp'PtMe(2)(C(O)NHR) suggest a stepwise process with deprotonation from a Pt(IV) species as the key step prompting elimination.
authors.affiliation: W.R. Kenan Laboratory, Department of Chemistry, University of North at Chapel Hill Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Bryan E
authors.initials: BE
authors.lastname: Frauhiger
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Ondisco
authors.forename: Peter S
authors.initials: PS
authors.lastname: White
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Templeton