Carbon-Centered Reactivity in Carbodiphosphorane-Based Ligands Allowing for Redox-Non-Innocent Ligand/Ligand Dual Bond-Activation.

A pronounced nucleophilicity in combination with a distinct redox non-innocence is a unique feature of a coordinated ligand, which in the current case, leads to unprecedented carbon-centered reactivity patterns: A carbodiphosphorane-based (CDP) pincer-type rhodium complex allows to cleave two C-Cl-bonds of geminal dichlorides via two consecutive SN2-type oxidative additions resulting in the formation of a stabilized carbene fragment. In the presence of a suitable reductant the carbene fragment can even be converted into olefines or hydrodehalogenation products in a catalytic reaction. The developed method can also be used to convert chlorofluorocarbons (CFCs) such as CH2ClF to fluoromethane and methane. The strong nucleophilic character of coordinated CDPs is also reflected in the low potential for oxidation, which favors radical reactivity and gives rise to an unique cationic C-centered radical CDP ligand, which is capable of a carbon-centered dihydrogen activation, following an unprecedented radical mechanism involving ligand-ligand-cooperativity (LLC).