Hydrazido(2–)-complexes of molybdenum and tungsten formed from dinitrogen complexes by protonation and ligand exchange

Dinitrogen Fixation: Rationalizing Strategies Utilizing Molecular Complexes

“… [113, 114] Mixtures of ammonia and hydrazine were observed for the molybdenum analogue, cis ‐[Mo(N 2 ) 2 (Me 2 PPh) 4 ] ( 124 ) under the same conditions [115, 116] . These studies were key to identify the relatively lower reactivity of trans isomers towards NH 3 formation [114] and constituted the first example of the use of H 2 SO 4 in methanol as a proton source for ammonia generation, which inspired many following studies [112] . Direct coordination of methanol to the metal centers in these reaction conditions was early proposed as a key step for ammonia formation [117] .…”

“…However, the cis ‐isomer of [W(N 2 ) 2 (Me 2 PPh) 4 ] ( 123 ) showed significantly higher activity, leading to the quantitative formation of ammonia upon treatment with H 2 SO 4 in methanol (Scheme 23). [113, 114] Mixtures of ammonia and hydrazine were observed for the molybdenum analogue, cis ‐[Mo(N 2 ) 2 (Me 2 PPh) 4 ] ( 124 ) under the same conditions [115, 116] . These studies were key to identify the relatively lower reactivity of trans isomers towards NH 3 formation [114] and constituted the first example of the use of H 2 SO 4 in methanol as a proton source for ammonia generation, which inspired many following studies [112] .…”

N‐Arylation and N,N‐Dibenzylation of Coordinated N2 with Organic Halides; Differences in the Reactivity of trans‐[Mo(N2)2(Me8[16]aneS4)] and Its Phosphane Analogues

“…When a more activated aryl halide p-IC,H,CO,Me was employed, 4 was obtained in a slightly better yield (32%). Formation of the aryldiazenido complexes was confirmed unequivocally by transformation of 3 into the hydrazido complex 5 on treatment with Me1 at room temperature and by a single crystal X-ray structure analysis of 4 ( [16]aneS,]. A decisive reaction would be an H abstraction from toluene by a methyl radical formed by an incipient reaction of 1 with Me1 together with [MoI(N,)Me8 [16]aneS,]; the latter would be N-benzylated by the benzyl radical thus generated.…”

“…If acetone is added to the above system, acetone azine (0. 16 The preference for a C, geometry can be rationalized based on PMO arguments. [51 Tilting C7 toward the C2-C3 double bond results in better overlap and thus higher stabilization than simultaneous interaction with both double bonds in a C,, arrangement.…”

Rethinking the Nitrogenase Mechanism: Activating the Active Site

“…29,96 Because of the work up conditions, it is still unknown whether N 2 H formation by the Mo N 2 ase, with an apparently limiting stoichiometry of one molecule of H 2 evolved per N 2 reduced;98 however, the experimental findings cannot eliminate that the H 2 evolved is still independent of N 2 reduction (perhaps by partially inactive species that cannot reduce N 2 but can reduce H + ). Significantly, H 2 inhibition is specific for N 2 reduction and does not affect C 2 H 2 or other reduction processes [99][100][101].…”