A number of square pyramidal o-semiquinonic nickel complexes with 2,6-bis(diphenylphosphinomethyl)phenyl were investigated by EPR spectroscopy in solution. The complexes have flexible coordination spheres and can exist in solution as two isomers rapidly (on the EPR timescale) interconverting one to another at room temperature. The equilibrium is entropy driven and does not significantly depend on the substituents in the semiquinone ring. The spin density distribution depends on mesomeric properties and bulkiness of substituents in ortho-position to oxygen atoms.
一系列方锥形的o-半醌
镍配合物与2,6-双(
二苯基膦甲基)苯进行了电子顺磁共振(EPR)光谱学研究。这些配合物具有灵活的配位球,并且在室温下可以作为两种异构体在溶液中快速(在EPR时间尺度上)相互转化。平衡是由熵驱动的,并且不显著依赖于半醌环中的取代基。自旋密度分布取决于取代基在氧原子邻位的共振性质和体积。