Interaction of organoplatinum(II) complexes with monovalent coinage metal triflates.
The organoplatinum(II) complexes [(NN)PtMe(2)] and [(NN)PtPh(2)] (NN = ArNC(Me)C(Me)NAr, Ar = 2,6-dichlorophenyl) can act as donor ligands for copper(I) and silver(I) triflates, affording a series of homo- and heteroleptic complexes which were characterized by X-ray diffraction. [(NN)PtMe(2)] binds to the coinage metals through short, ligand-unsupported d-d(10) contacts that are best described as Pt-->M dative bonds (M = Cu, Ag), in which the d(z(2)) orbital of the square-planar Pt(II) center donates electron density to the Lewis-acidic metal. Spectroscopic studies in solution and DFT calculations corroborate this description. [(NN)PtPh(2)] binds preferentially by eta(1) or eta(2) complexation of the ipso carbon atoms of the phenyl groups to the coinage metal, affording homoleptic complexes {[(NN)PtPh(2)](2)M}(+){TfO}(-) in the solid state. The 1:1 adducts of formula {[(NN)PtPh(2)]M(OTf)}(n) (M = Cu, n = 1; M = Ag, n = 2) are observed in solution, and a 1:2 adduct of formula {[(NN)PtPh(2)]Ag(2)(OTf)(2)(C(6)H(6))}(n) was characterized in the solid state, showing that unsupported Pt-->M bonds are also accessible for [(NN)PtPh(2)]. The thermolyses of the complexes [(NN)PtMe(2)]MOTf in benzene affords moderate yields of [(NN)PtPh(2)] through an oxidatively induced double C-H activation process.
Moret
Marc-Etienne
ME
Laboratorium für Organische Chemie, Eidgenössische Technische Hochschule (ETH) Zürich, CH-8093 Zürich, Switzerland.
Chen
Peter
P