Staun Selena L, Sergentu Dumitru-Claudiu, Wu Guang, Autschbach Jochen, Hayton Trevor W
Department of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106 , USA . Email:
Department of Chemistry , University at Buffalo , State University of New York , 312 Natural Sciences Complex , Buffalo , NY 14260-3000 , USA . Email:
Chem Sci. 2019 Jun 4;10(26):6431-6436. doi: 10.1039/c9sc01960j. eCollection 2019 Jul 14.
Reaction of the thorium metallacycle, [Th{N(R)(SiMe)CH}(NR)] (R = SiMe) with 1 equiv. of NaNH in THF, in the presence of 18-crown-6, results in formation of the bridged thorium nitride complex, [Na(18-crown-6)(EtO)][(RN)Th(μ-N)(Th(NR)] (), which can be isolated in 66% yield after work-up. Complex is the first isolable molecular thorium nitride complex. Mechanistic studies suggest that the first step of the reaction is deprotonation of [Th{N(R)(SiMe)CH}(NR)] by NaNH, which results in formation of the thorium bis(metallacycle) complex, [Na(THF) ][Th{N(R)(SiMeCH)}(NR)], and NH. NH then reacts with unreacted [Th{N(R)(SiMe)CH}(NR)], forming [Th(NR)(NH)] (), which protonates [Na(THF) ][Th{N(R)(SiMeCH)}(NR)] to give . Consistent with hypothesis, addition of excess NH to a THF solution of [Th{N(R)(SiMe)CH}(NR)] results in formation of [Th(NR)(NH)] (), which can be isolated in 51% yield after work-up. Furthermore, reaction of [K(DME)][Th{N(R)(SiMeCH)}(NR)] with , in THF- , results in clean formation of , according to H NMR spectroscopy. The electronic structures of and were investigated by N NMR spectroscopy and DFT calculations. This analysis reveals that the Th-N bond in features more covalency and a greater degree of bond multiplicity than the Th-NH bond in . Similarly, our analysis indicates a greater degree of covalency in comparable thorium imido and oxo complexes.
钍金属环化合物[Th{N(R)(SiMe)CH}(NR)]（R = SiMe）与1当量的NaNH在四氢呋喃中，在18-冠-6存在下反应，生成桥联氮化钍配合物[Na(18-冠-6)(EtO)][(RN)Th(μ-N)(Th(NR)]（），后处理后可分离得到，产率为66%。配合物是首个可分离的分子氮化钍配合物。机理研究表明，反应的第一步是NaNH使[Th{N(R)(SiMe)CH}(NR)]去质子化，生成钍双（金属环）配合物[Na(THF) ][Th{N(R)(SiMeCH)}(NR)]和NH。NH随后与未反应的[Th{N(R)(SiMe)CH}(NR)]反应，形成[Th(NR)(NH)]（），其使[Na(THF) ][Th{N(R)(SiMeCH)}(NR)]质子化得到。与假设一致，向[Th{N(R)(SiMe)CH}(NR)]的四氢呋喃溶液中加入过量NH会生成[Th(NR)(NH)]（），后处理后可分离得到，产率为５１％。此外，根据核磁共振氢谱，[K(DME)][Th{N(R)(SiMeCH)}(NR)]与在四氢呋喃-中反应可直接生成。通过核磁共振氮谱和密度泛函理论计算研究了和的电子结构。该分析表明，中的Th-N键比中的Th-NH键具有更多的共价性和更大程度的键多重性。同样，我们的分析表明，在类似的钍亚胺基和氧代配合物中也具有更高程度的共价性。
