Square Planar Nucleophilic and Radical Pt(II) Carbenes

A square planar platinum­(II)
carbene complex [{PC­(sp2)­P}H­Pt­(PMe3)] ([PC­(sp2)­P]H = (bis­[2-(di-iso-propyl­phos­phino)­phenyl]­meth­ylene)
was synthesized through the dehydrohalogenation of [{PC­(sp3)­HP}H­PtCl] in a microwave reactor.
The tert-butyl substituted analogue, [{PC­(sp2)­P}tBu­Pt­(PMe3)] ([PC­(sp2)­P]tBu =
bis­[2-(di-iso-propyl­phos­phino)-4-tert-butyl­phenyl]­meth­ylene), was synthesized
via an analogous route. The nucleophilic nature of the carbene carbon
was confirmed through DFT calculations and reactivity with HCl. Additionally,
[{PC­(sp2)­P}H­Pt­(PMe3)] was treated with 0.5 equiv of I2 to generate a paramagnetic
product, [{PC­(sp2)­P}H­PtI].
The Evans method and EPR spectroscopy revealed that a one-electron
oxidation occurred at the carbene carbon, thus generating a persistent
radical carbene.