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Synthesis of Isonitrile, Iminoacyl, and Aminocarbene Tp′Pt Complexes

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posted on 08.11.2010, 00:00 by Kristi L. Engelman, Peter S. White, Joseph L. Templeton
Generation of a reactive Tp′PtMe fragment (Tp′ = hydridotris(3,5-dimethylpyrazolyl)borate) in the presence of free isonitrile leads to a σ-isocyanide Pt(II) complex. Related Pt(II) aminocarbene complexes can be synthesized by nucleophilic attack at the isonitrile carbon followed by addition of acid. Protonation at nitrogen produces the observed aminocarbene product. Nucleophilic attack at the carbon of the coordinated isonitrile by metal alkyl reagents followed by addition of iodomethane as an electrophilic reagent results in Pt(IV) iminoacyl complexes of the type Tp′Pt(RCN(2,6-C6Me2H3))Me2, where R = Me, Et. Alternatively, the Pt(II) aminocarbene complexes can be converted to these same Pt(IV) iminoacyl products by deprotonation of the N−H site followed by addition of iodomethane, with the outcome reflecting methylation at platinum. Addition of acid to the Pt(IV) iminoacyl complex generates a rare cationic Pt(IV) aminocarbene complex via protonation at the iminoacyl nitrogen as {Tp′Pt(C(R)NH(2,6-C6Me2H3))Me2}{BF4} forms.