ELECTROCHEMICAL REDUCTION OF THE UNSATURATED CYCLIC TRINUCLEAR PD-3(DPPM)(3)CO2+ CLUSTER (DPPM = ((C6H5)(2)P)(2)CH2)

Pd-3(dppm)(3)CO2+ exhibits a two-electron reduction process at similar to-0.5 V vs. SCE in 0.2 M Bu4NPF6 solutions of organic solvents such as dry acetonitrile, N,N-dimethylformamide (DMF), tetrahydrofuran (THF ), and dichloromethane to reversibly produce the zero valent Pd-3(dppm )(3)CO, which exhibits a nu(CO) band in the 1761-1766 cm(-1) range in the IR spectra. The mechanistic aspects of this multistep two-electron process are discussed experimentally on the basis of r.d.e. (rotating disk electrode) voltammetry, cyclic voltammetry, and electrolysis res ults. Geometry optimizations using DFT (Density Functional Theory) pre dict that the Pd-Pd and C=O bond lengths are 3.008 and 1.182 Angstrom, respectively, which compare favorably with the experimental data for other zero valent polynuclear complexes.