Development of Molecular Metal Chains Supported by Multidentate Phosphines

摘要

This account reports recent development of linearly ordered multinuclear transition-metal complexes, or molecular metal atom chains, supported by multidentate phosphines, which could be important motifs for nano-structured molecular devices. In particular, it focuses on our recent results of platinum-based homo- and hetreromultimetallic complexes supported by a triphosphine ligand, bis(diphenylphosphinomethyl)phenylphosphine (dpmp), in which strategic synthetic methods of cluster core expansion have been established from Pt_(2) complexes to Pt-Pt-M (M = Pt, Pd, Ir, Rh, Au, Ag, Cu) and Pt-M-Pt (M = Pt, Pd), and to the linear Pt_(2)M_(2)Pt_(2) molecular chains (M = Pt, Pd) as well as one-dimensional assemblage of the linear Pt_(3) units connected by bisisocyanide linkers. A linear tetraphosphine, meso-bis{(diphenylphosphinomethyl)phenylphosphino}methane (dpmppm), was synthesized to support linearly ordered tetranuclear metal chains, leading to successful isolation of the linear Pd_(8) complexes, ~(4+) and ~(4+) (Xyl = 2,6-xylyl) which showed a Pd-Pd bonded linear structure and an interesting thermochromic behavior. The dpmppm ligand also supported flexibly bending Au_(4) complexes with a photochemical switch upon recognizing counter anions, and Au_(4)M_(2)Cu_(2) heterometallic rings, ~(4+) (M = Au, Ag, Cu), exhibiting strong inclusion behavior for a BF_(4)~(-) anion into pore of the Au_(4)Ag_(2)Cu_(2) ring.