Relieving Steric Strain at Octahedral Platinum(IV): Isomerization and Reductive Coupling of Alkyl and Aryl Chlorides

Oxidation of monocyclometalated platinum­(II) complexes
results
in octahedral platinum­(IV) complexes. Depending on the substitution,
two different reactions occur: either a simple isomerization, resulting
in the exchange of ligand positions, or a reductive coupling of aryl
chloride. With a doubly cyclometalated complex, stability of the oxidized
form is dependent on isomeric form: whereas the trans isomer is robust, being manipulable in air at room temperature,
the cis isomer decomposes at −20 °C and
above. Reductive coupling at this cis isomer is 100%
selective for alkyl chloride over aryl chloride and is suggested to
be a concerted process.