Doyle Laurence R, Wooles Ashley J, Liddle Stephen T
School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Angew Chem Int Ed Engl. 2019 May 13;58(20):6674-6677. doi: 10.1002/anie.201902195. Epub 2019 Apr 8.
Although reductive cleavage of dinitrogen (N ) to nitride (N ) and hydrogenation with dihydrogen (H ) to yield ammonia (NH ) is accomplished in heterogeneous Haber-Bosch industrial processes on a vast scale, sequentially coupling these elementary reactions together with a single metal complex remains a major challenge for homogeneous molecular complexes. Herein, we report that the reaction of a chloro titanium triamidoamine complex with magnesium effects complete reductive cleavage of N to give a dinitride dititanium dimagnesium ditriamidoamine complex. Tandem H splitting by a phosphine-borane frustrated Lewis pair (FLP) shuttles H atoms to the N , evolving NH . Isotope labelling experiments confirmed N and H fixation. Though not yet catalytic, these results give unprecedented insight into coupling N and H cleavage and N-H bond formation steps together, highlight the importance of heterobimetallic cooperativity in N activation, and establish FLPs in NH synthesis.
尽管在多相哈伯-博施法工业过程中，二氮（N₂）还原裂解为氮化物（N³⁻）并与氢气（H₂）氢化生成氨（NH₃）已大规模实现，但将这些基元反应与单一金属配合物顺序偶联，对于均相分子配合物而言仍是一项重大挑战。在此，我们报道了一种氯代三氨基胺钛配合物与镁的反应，可实现N₂的完全还原裂解，生成一种二氮二钛二镁二三氨基胺配合物。由膦-硼受阻路易斯酸碱对（FLP）进行的串联H₂裂解将H原子穿梭至N³⁻，生成NH₃。同位素标记实验证实了N₂和H₂的固定。尽管尚未实现催化，但这些结果为将N₂裂解、H₂裂解以及N-H键形成步骤偶联在一起提供了前所未有的见解，突出了异双核协同作用在N₂活化中的重要性，并确立了FLP在NH₃合成中的作用。
