Electron-Deficient η~1-Indenyl, η~3-allylpalladium(Ⅱ) Complexes Stabilized by Fluxional Non-covalent Interactions

摘要

Highly fluxional, solution-persistent, and formally electron-deficient (32e~-) binuclear Pd(Il)-C(0) complexes of 2-methyl-lH-indene were synthesized and structurally characterized by X-ray diffraction analysis. DFT investigations combined with a number of theoretical analyses of the bond framework suggest that the polar intermetallic interaction possesses no major covalent character. Instead of bearing a static metal-metal bond as suggested by structural X-ray diffraction analysis, the complexes display in solution significant fluxionality through haptotropy, i.e., a formal "oscillation" of the Pd(η~3-allyl) moiety between two limiting η~1-indenyl configurations.