| Summary: | 碩士 === 國立清華大學 === 化學系 === 95 === Dinuclear commonsoles M2[N2N]2 where M ＝ V, Cr, Mn or Mo and [N2N] ＝ 4-methylpyridine(NC6H3-i-Pr2)2 or pyridine(NSiMe3)2 were prepared and fully characterized. We also report the isolation and structural characterization of the first complex having an Mn22+ core in (K-18-crown-6){Mn2K[N2N]2}. This Mn-K-Mn type of bonding, involving three atoms and two bonding electrons per bridge, is described as three-center, two-electron bonding.
Dinuclear inverted sandwiches (μ-η6:η6-Arene)[M(Nacnac)], where Arene ＝ toluene or benzene, M ＝ V, Cr, and Nacnac ＝ HC((CMe)NC6H3-i-Pr2)2 were prepared and fully characterized. Their dinuclear nature was confirmed by single crystal X-ray diffraction and the valency of each metal was determined to be I by X-ray absorption spectroscopy. Through arenes bridge two metal centers in a symmetrical η6, η6 fashion in solid state, the bridging arene ligands in (μ-η6:η6-Arene)[V(Nacnac)] tend to dissociate in solution, while the bridging mode of arene ligands in (μ-η6:η6-Arene)[Cr(Nacnac)] can be identified in solution by 2H-NMR spectroscopy when arenes were replaced by deuterated arenes. Despite their different behavior in solutions, both inverted sandwiches act as two [M(Nacnac)] synthetic equivalents when treated with appropriate substrates accompanied by the extrusion of arenes. For example, both complexes react with organic azides to produce bis(imido) complexes with the liberation of N2. They are also able to effect the cleavage of N-N double bonds of azobenzene and engendered the formation of imido complexes. Reaction of both inverted sandwiches with other substrates such as O2, N2, N2O, PhCCH, and PhCN will be covered as well. As a result, both inverted sandwiches behave as multi-electron reductants.
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