Masai Kohei, Shirato Katsunori, Yamamoto Koji, Kurashige Yuki, Murahashi Tetsuro
Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
Chem Commun (Camb). 2016 May 11;52(38):6427-30. doi: 10.1039/c6cc01536k. Epub 2016 Apr 20.
Metal clusters are effectively stabilized by bridging π-coordination of planar π-conjugated unsaturated hydrocarbons. However, the mechanism of π-envelopment of a metal cluster has been elusive. By employing 1,2-bis(4-aryl-1,3-butadienyl)benzene as the π-conjugated ligand, we found that the π-envelopment of a Pd4 cluster proceeded in a stepwise manner, where the sp(2)-carbon ligands initially envelop the Pd4 cluster through a bent binding mode, and then isomerized to a thermodynamically more stable planar mode under mild heating or visible light irradiation. The involvement of a bent binding mode indicates the kinetically preferred coordination at the axial coordination site trans to a metal-metal bond.
金属簇通过平面π共轭不饱和烃的桥联π配位而有效地稳定。然而，金属簇的π包封机制一直难以捉摸。通过使用1,2-双（4-芳基-1,3-丁二烯基）苯作为π共轭配体，我们发现Pd4簇的π包封以逐步方式进行，其中sp(2)-碳配体最初通过弯曲的结合模式包围Pd4簇，然后在温和加热或可见光照射下异构化为热力学上更稳定的平面模式。弯曲结合模式的参与表明在与金属-金属键反位的轴向配位位点上动力学上优先的配位。
