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Fac-[(CO)₃Mo(P^tBu₂N^Ph₂)(NH₃)] catalyzed NH₃oxidation to N₂using phenoxyl radicals as H atom acceptors generating up to 88 equiv. N₂per Mo centre. 

Exposure of (POCOP^tBu)Cr(Bn) to 427 nm blue light under 1 atm N₂ promoted Cr–C_Bn bond homolysis and led to N₂ activation forming [(POCOP^tBu)Cr]₂(μ-N₂). 

Cr(N₂)₂(diphosphine)₂ complexes catalyze the reduction of dinitrogen at room temperature using SmI₂ and ethylene glycol or H₂O to form hydrazine and ammonia. 

We report the synthesis of molybdenum and tungsten bromo dicarbonyl complexes (POCOP^tBu)M^IIBr(CO)₂(M  =  Mo or W; POCOP^tBu  =  κ³-C₆H₃-1,3-[OP( tBu)₂]₂) supported by an anionic PCP pincer ligand, and the chromium complex (PNP^tBu)Cr⁰(CO)₃(PNP^tBu  =  2,6-bis(di- tert-butyl-phosphinomethyl)pyridine) bearing a neutral PNP pincer scaffold. The three group six complexes described in this study have been characterized by Liquid Injection Field Desorption Ionization Mass Spectrometry (LIFDI-MS), NMR, and IR spectroscopy. Single crystal X-ray diffraction studies show the Mo^IIand W^IIcomplexes adopt a six-coordinate distorted trigonal prismatic geometry, whereas the Cr⁰complex exhibits a distorted octahedral geometry. 

Abstract Hybrid polyaromatic hydrocarbons (PAHs) consisting of helicene and acene domains, referred to as [7]heli‐D‐acenes, are introduced as scaffolds to generate enantiopure twisted acenes (heli‐twistacenes) by a torque, lock, and propagate (TLP) approach. Computational methods with and without dispersion corrections were used to explore the structural and electronic features of these PAHs and to explore the possible formation of twistomers that might complicate reaction mixtures. Syntheses of unsubstituted and disubstituted members of the [7]heli‐D‐acene series confirmed the viability of the TLP approach, and together with the computational results, provided proof‐of‐concept of this new approach as a viable means to generate enantiopure twisted‐acenes. The X‐ray structures, absorption, fluorescence, phosphorescence, and CD spectra of these first generation heli‐acenes are compared to the structure and photophysical properties of pentacene and [7]helicene. A high barrier for the enantio‐enriched M enantiomer of 19,24‐dicyano[7]heli‐D‐anthracene verified its configurational stability at room temperature. 

Abstract We report a nickel complex for catalytic oxidation of ammonia to dinitrogen under ambient conditions. Using the aryloxyl radical 2,4,6‐tri‐tert‐butylphenoxyl (^tBu₃ArO⋅) as a H atom acceptor to cleave the N−H bond of a coordinated NH₃ligand up to 56 equiv of N₂per Ni center can be generated. Employing theN‐oxyl radical 2,2,6,6‐(tetramethylpiperidin‐1‐yl)oxyl (TEMPO⋅) as the H‐atom acceptor, up to 15 equiv of N₂per Ni center are formed. A bridging Ni‐hydrazine product identified by isotopic nitrogen (¹⁵N) studies and supported by computational models indicates the N−N bond forming step occurs by bimetallic homocoupling of two paramagnetic [Ni]−NH₂fragments. Ni‐mediated hydrazine disproportionation to N₂and NH₃completes the catalytic cycle.