Light-Driven Methyl Exchange Reactions in Square-Planar Palladium(II) and Platinum(II) Complexes

Square-planar palladium­(II) and platinum­(II) methyl complexes with terpyridine and 6,6″-diamino terpyridine ligands undergo methyl exchange reactions upon exposure to light. The half-life of the methyl exchange reactions correlates with the relative Pd–C and Pt–C bond strengths. No exchange between methyl and phenyl groups is observed, probably due to the stronger Pt–C bond in the platinum phenyl complex. A mechanism is proposed whereby a dinuclear intermediate is generated upon irradiation that has a weakened M–C bond in the excited state, resulting in the observed methyl exchange reactions.

带有三联吡啶（terpyridine）与6,6″-二氨基三联吡啶（6,6″-diamino terpyridine）配体的平面正方形钯(II)（palladium(II)）及铂(II)（platinum(II)）甲基配合物，在光照条件下可发生甲基交换反应。该反应的半衰期与Pd-C、Pt-C键的键强存在相关性。未观测到甲基与苯基之间的交换过程，这大概率是由于苯基铂配合物中Pt-C键强度更高。本文提出了如下反应机理：辐照过程中会生成双核中间体，该中间体在激发态下存在弱化的M-C键，进而引发所观测到的甲基交换反应。