Synthesis and Characterization of Fe<sup>0sup>(2,2′-bipyridine) (2-aminoethyl-pyridine) and its Reaction with Dihydrogen
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- 作者：Prof. Angela Dibenedetto ; Dr. Cristina E. Roth ; Prof. Michele Aresta and Dr. Imre Pá ; pai
- 刊名：ChemSusChem
- 出版年：2017
- 出版时间：January 10, 2017
- 年：2017
- 卷：10
- 期：1
- 页码：220-225
- 全文大小：1170K
- ISSN：1864-564X
文摘
Fe<sup>0sup>(bpy)(pyea) (2; bpy=2,2′-bipyridine, pyea=2-aminoethyl-pyridine), a 16-electron species, was synthesized by reduction of FeCl<sub>2sub>(bpy)(pyea) (1) using Na-strips. It is a diamagnetic low-melting solid (m.p. 295 K) stable under N<sub>2sub> and easily decomposed by radiations even at low temperature. It was fully characterized by elemental analyses and multinuclear NMR. Complex 2 acts as an active hydrogenation catalyst, but has a very short lifetime. In fact, it reacts with H<sub>2sub> (0.1–1 MPa) at room temperature in toluene and affords in a few minutes a new Fe<sup>0sup> complex characterized as Fe<sup>0sup>(bpy)(η<sup>6sup>-picoline) (3), inactive to hydrogenation. Picoline is derived from the sp<sup>3sup>–sp<sup>3sup> C−C bond cleavage of the aminoethyl arm of the pyea ligand. The rapid evolution of the putative intermediate FeH<sub>2sub>(bpy)(pyea) (4) has not allowed the isolation such Fe-hydrido species. The interaction of H<sub>2sub> with 2 has been studied by DFT, which has allowed to demonstrate that 3 is lower in energy than 2+H<sub>2sub>, justifying the fact that the intermediate dihydride was not isolated. Interestingly, 3 was also obtained by reaction of 1 with NaBH<sub>4sub> or with glycerol–KOH. Complex 2 is one of the rare examples of Fe<sup>0sup> complex stabilized by a set of only N-donor atoms. The reaction with glycerol confirms the potential role of Fe in catalytic hydrogenation reactions using bio-glycerol as a H-source.