Synthesis and characterization of heterometallic trinuclear metals bonded other metals frameworks and Investigations of unusual dinuclear compounds containing metal-metal multiple bonds.

摘要

Application of a general preparative route results in access to trinuclear MMM'(dpa)4Cl2 compounds (dpa = 2,2'-dipyridylamide). These complexes feature heterometallic Cl--M ≡ M···M'--Cl connectivities, in which a paramagnetic first-row transition metal M' (M' = Cr(II), Mn(II), Fe(II), Co(II)) is in close axial proximity to a diamagnetic quadruply bonded M ≡ M unit (M = Cr(II), Mo(II), W(II)). Systematic variations of the nature of M and M' in these systems are possible because the synthetic approach involves metallation of dinuclear precursors M2(dpa) 4 with appropriate metal salts M'Cl2. The unusual structural, spectroscopic and electrochemical properties of these systems are described in detail.;The second part of the thesis focuses on the oxidation chemistry of the dinuclear compounds M2(dpa)4 (M = Mo, W). Interestingly, the tridentate dpa ligand stabilizes a variety of oxidation states and uncommon geometries around the dinuclear unit. Most importantly, it was found that four-electron oxidation of W2(dpa)4 yields a unique terminal oxo compound with a W(IV)W(IV)O core which displays unusual reactivity in that it doesn't react via oxygen atom transfer with tertiary phosphines, but instead undergoes four consecutive one-electron reductions to refurnish the quadruply bonded W2(dpa)4.