Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Current address: Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands.
Angew Chem Int Ed Engl. 2022 Oct 24;61(43):e202209655. doi: 10.1002/anie.202209655. Epub 2022 Sep 20.
Terminal iron nitrides (Fe≡N) have been proposed as intermediates of Fe-mediated nitrogen fixation, and well-defined synthetic iron nitrides have been characterized in high oxidation states, including Fe , Fe , and Fe . This study reports the generation and low temperature characterization of a terminally bound iron(III) nitride, P Fe(N) (P =tris(o-diisopropylphosphinophenyl)borane), which is a proposed intermediate of iron-mediated nitrogen fixation by the P Fe-catalyst system. CW- and pulse EPR spectroscopy (HYSCORE and ENDOR), supported by DFT calculations, help to define a A ground state electronic structure of this C -symmetric nitride species, placing the unpaired spin in a sigma orbital along the B-Fe-N vector; this electronic structure is distinct for an iron nitride. The unusual d -configuration is stabilized by significant delocalization (≈50 %) of the unpaired electron onto the axial boron and nitrogen ligands, with a majority of the spin residing on boron.
末端铁氮化物（Fe≡N）被认为是铁介导固氮的中间体，并且已经对高氧化态的定义明确的合成铁氮化物进行了表征，包括 Fe 、Fe 和 Fe 。本研究报告了末端结合的铁（III）氮化物 P Fe(N)（P = 三（邻二异丙基膦基）苯硼）的生成和低温表征，该氮化物是 P Fe 催化剂体系铁介导固氮的中间产物。连续波和脉冲电子顺磁共振波谱（HYSCORE 和 ENDOR）结合密度泛函理论计算，有助于确定该 C 对称氮化物物种的 A 基态电子结构，将不成对的自旋置于沿 B-Fe-N 矢量的 sigma 轨道中；这种电子结构对于铁氮化物来说是独特的。这种不寻常的 d 构型通过不成对电子显著离域（≈50%）到轴向硼和氮配体上得到稳定，自旋的大部分位于硼上。
