Reactivity of [Pt(CH2CH2)(PPh3)2] toward ethyldiazocetate. Synthesis and molecular structure of the diethyl fumarate complex [Pt{trans-CH(CO2Et)CH(CO2Et)}(PPh3) 2] and preparation of the analogous diethyl maleate compound

Treatment of [Pt(CH2CH2)(PPh3)2] with NNCHCO2Et (ethyldiazoacetate) or with trans-CH(CO2Et) CH(CO2Et) (diethyl fumarate) affords [Pt{trans-CH(CO2Et)CH(CO2Et)}(PPh3)2] (1), whereas [Pt{cis-CH(CO2Et)CH(CO2Et)}(PPh3)2] (2) is obtained from the reaction with cis-CH(CO2Et)CH(CO2Et) (diethyl maleate). The molecular structure of 1 has been confirmed by X-ray diffraction analysis which indicates that the diethyl fumarate ligand binds to platinum via the olefinic bond, a weak metal-α-C(olefin)-H interaction also having been detected; the corresponding PtC distance is 2.110(3) A, and the olefinic CC bond length is 1.466(6) A. The redox properties of these complexes, as studied by cyclic voltammetry and controlled potential electrolysis, are also described.