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

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.