含十五或十六族元素之過渡金屬羰基團簇化合物與聚合物：從合成到應用(2/2)

A novel family of five Mn?Te?CO complexes was prepared via facile syntheses: mono spirocyclic 1, four-membered Mn2Te2 ring type 2, hydride-containing square pyramidal 3, and dumbbell-shaped 4 and 5. Electron-precise complexes 4 and 5 exhibit unusual paramagnetism arising from two types of Mn atoms in different oxidation states, as determined by X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations. The structural transformations from small-sized Mn4Te 1 and Mn2Te2 2 to the largest Mn6Te10 5 were controllable, the off/on magnetic switched transformation between HMn3Te2 3 and 5 was reversible, and a magnetic transformation between Mn6Te6 4 and 5 was observed. Interestingly, the reversible dehydridation and hydridation between the HMn3Te2-based cluster 3 and [Mn3Te2(CO)9]? were successfully accomplished, in which the release of a high yield of H2 was detected by gas chromatography (GC). In addition, upon the addition of CO, cluster 3 first forms a carbonyl-inserted intermediate 3', detected by the high resolution ESI-MS, which is readily transformed to a dimeric di-hydrido cluster 6 with the introduction of O2. These low- to high-nuclearity complexes exhibit rich redox properties with semiconducting behavior in solids possessing low but tunable energy gaps (1.06?1.62 eV) due to efficient electron transport via nonclassical C?H···O(carbonyl) interactions. The structural nature, reversible structural transformations, controllable on/off magnetic switches, electron communication networks, and associated chemical properties for hydrogen generation are discussed in detail and supported by DFT calculations, density of states, band structures, and noncovalent interaction analyses. A 4-center, 6π-conjugated, multiply-bonded trigonal-planar complex 7 was synthesized via the hydride abstraction of 7-H with HBF4·H2O, with the release of high yields of H2. The oxidation state of the Sb atom in [Et4N][7] was well-defined as 0, which was evidenced by XPS and XANES. The distinct color-structure relationship of this low-valent Sb complex 7 toward a wide range of organic solvents was demonstrated, as interpreted by TDDFT calculations, allowing the trigonal-planar 7 and the tetrahedral solvent adducts to be probed, revealing dual acid/base properties of the Sb center. In addition, 7 showed pronounced electrophilicity toward anionic and neutral nucleophiles, even with solvent molecules, to produce tetrahedral complexes 7-Nu. On the contrary, the Fe/Cr hydride complex 8-H was obtained by treating 7 with [HFe(CO)4]–. Upon hydride abstraction of 8-H with HBF4·H2O or [CPh3][BF4], a multiply-bonded Fe/Cr trigonal-planar complex 8 was produced, in which oxidation coupling Sb2-containing complexes 9-Cr and 9-H were yielded as final products. Complex 9-Cr exhibited dual Lewis acid/base properties via hydridation and protonation reactions, to form 8-H or 9-H, respectively. Surprisingly, complex [Et4N][7] possessed a low energy gap of 1.13 eV with the electrical conductivity in the range of (1.10–2.77) x 10–6 S?cm–1, showing that complex [Et4N][7] was a low-energy-gap semiconductor. The crystal packing, crystal indexing, and density of state (DOS) results of [Et4N][7] further confirmed the efficient through-space conduction pathway via the intermolecular Sb???O(carbonyl) and O(carbonyl)???O(carbonyl) interactions of the 1D anionic zig-zag chain of 7.