Dinitrogen Cleavage by a Diniobium Tetrahydride Complex: Formation of a Nitride and Its Conversion into Imide Species

Abstract

Glatte Trennung: Mit Distickstoff reagieren Lösungen des Hydridkomplexes [K(dme)]2[{Nb}2(μ‐H)4] (siehe Schema) unter Bildung des Nitridkomplexes [K(thf)2]2[{Nb}2(μ‐N)2] und H2. Bei diesem Prozess wird die Dreifachbindung von Distickstoff gespalten. Die Nitridliganden sind mit MeI stufenweise alkylierbar, wobei über einen Nitrid‐Imid‐Komplex schließlich ein Bis(imid)komplex entsteht.

New Approaches to Functionalizing Metal‐Coordinated N2

“…The lesson from comparing Equations (2) and (3) in Table 1 is that it is daunting to try to consume two N 2 molecules. A similar conclusion comes from comparing Equation (11), in which alkyne serves as fuel, and Equation (12), which consumes two N 2 molecules.…”

“…It was noted above that the adjacent (vicinal) nitrogen atoms experience lone pair/lone pair (filled/filled) repulsions, which makes the N À N bond in hydrazines weak. This situation also suggests that low-energy mechanisms exist for N À N cleavage, either using H 2 or reducing equivalents (2 e À ), to cleave the species shown in Equation (12) of Table 1 into urea; this could be a way to reverse the otherwise endothermic N 2 functionalization in Equation (12). Similarly, if NH 3 is desired, it and pyrrole are to be formed from pyridazine by PCET (Scheme 2).…”

“…A current goal of global importance is the conversion of diatomic nitrogen to value-added organonitrogen compounds. While improved, [1][2][3][4][5][6][7][8][9][10][11][12][13] less-energy intensive hydrogenation of coordinated N 2 ("nitrogen fixation", forming NH 3 ) is an attractive, if challenging goal owing to the importance of agricultural fertilizers, there are broader goals for organonitrogen compounds, including other fertilizers (e.g., urea), but also compounds useful in pharmaceutical and electronic materials applications. [14] The purpose of this Essay is to show that, in the absence of available experimental thermochemical data, it can be useful to go "prospecting", using density functional theory (DFT) calculations, for organic molecules with which to "derivatize" N 2 .…”

Structure and Reactivity of a Hafnocene μ‐Nitrido Prepared From Dinitrogen Cleavage

“…The six‐electron cleavage of molecular nitrogen by soluble metal complexes to form either terminal1 or bridging nitrido2 compounds is an attractive transformation for developing synthetic routes to organic molecules using N 2 as the nitrogen source 3. Acylation,4 silylation,5 alkylation6 and hydrogenation7 have all been identified as viable strategies to construct new bonds to metal–nitrido complexes following N 2 cleavage. Despite numerous examples in Groups 5 and 6, to our knowledge, a Group 4 transition metal nitrido complex has not been isolated following N 2 cleavage.…”

N2 Activation by a Hafnium Complex: A DFT Study on CO‐Assisted Dinitrogen Cleavage and Functionalization

“…This implies that the NN bond scission (via TS5/9 or TS7/8 ) is irreversible. In general, it is usually proposed that N 2 cleavage takes place at low‐valent metal (Mo III ,3a, 22 Nb IV ,12c, 23 and Ta III [3f, 24] ) complexes in which the metal stores enough electrons to break the NN bond. What about the high‐valent Chirik Hf IV complex?…”