Theoretical study on the mechanism of catalytic reduction of hydrazine to ammonia mediated by vanadium (III) thiolate complexes

Guha, Ankur Kanti; Phukan, Ashwini K.

doi:10.1016/j.ica.2010.06.014

Cited by 4 publications

(3 citation statements)

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“…A number of other theoretical treatments of the energetics of the Schrock cycle and related systems have appeared that, in part, considered larger models of the catalysts. − On the basis of a model of the [Mo( HIPT N 3 N)] complex, where the HIPT residues are replaced by phenyl groups (Figure b), Cao et al treated all intermediates of the Schrock cycle (N 2 , NNH + , ..., NH 3 ) with DFT, employing the BLYP functional . Moreover, ammonium (NH 4 + ) was considered as the proton source and an iron–sulfur cluster as the electron donor.…”

Section: Introductionmentioning

confidence: 99%

Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [Mo^HIPTN₃N] Catalyst

et al. 2015

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A series of density functional theory (DFT) calculations on the full [Mo(HIPT)N3N] catalyst are performed to obtain an energy profile of the Schrock cycle. This is a continuation of our earlier investigation of this cycle in which the bulky hexaisopropyterphenyl (HIPT) substituents of the ligand were replaced by hydrogen atoms (Angew. Chem., Int. Ed. 2005, 44, 5639). In an effort to provide a treatment that is as converged as possible from a quantum-chemical point of view, the present study now fully takes the HIPT moieties into account. Moreover, structures and energies are calculated with a near-saturated basis set, leading to models with 280 atoms and 4850 basis functions. Solvent and scalar relativistic effects have been treated using the conductor-like screening model and zeroth-order regular approximation, respectively. Free reaction enthalpies are evaluated using the PBE and B3LYP functionals. A comparison to the available experimental data reveals much better agreement with the experiment than preceding DFT treatments of the Schrock cycle. In particular, free reaction enthalpies of reduction steps and NH3/N2 exchange are now excellently reproduced.

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Section: Introductionmentioning

confidence: 99%

Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [Mo^HIPTN₃N] Catalyst

et al. 2015

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“…However, no ammonia was formed using this catalyst under the same condition that was successful with the analogous molybdenum catalyst. Hence, it could be rewarding to carry out a thorough theoretical investigation on the mechanism of dinitrogen fixation mediated by vanadium and to compare it with the well established chemistry of molybdenum (Scheme ). − To the best of our knowledge, until now, there exists no systematic study in the literature about nitrogen fixation catalyzed by vanadium complexes except the one by us where mechanistic details for the conversion of hydrazine to ammonia mediated by vanadium thiolate complex were studied . We report here, for the first time, a systematic theoretical study on the thermodynamics of dinitrogen fixation mediated by vanadium triamidoamine complex and compared its results with the energetics obtained for the similar molybdenum complex.…”

Section: Introductionmentioning

confidence: 98%

Why Vanadium Complexes Perform Poorly in Comparison to Related Molybdenum Complexes in the Catalytic Reduction of Dinitrogen to Ammonia (Schrock Cycle): A Theoretical Study

Guha

Phukan

2011

Inorg. Chem.

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Energetics and mechanistic details for the conversion of dinitrogen to ammonia mediated by vanadium triamidoamine has been studied theoretically involving various mechanistic possibilities. For most of the cases, protonation at the amido nitrogen atom is more favorable compared to the terminal one. Further, the most important steps of the mechanism were compared with the well established chemistry of nitrogen fixation mediated by molybdenum. Such a comparison helps in understanding why vanadium triamidoamine complex performs poorly compared to molybdenum. The main factors responsible for the poor performance of the vanadium complex toward NH(3) production are identified as low exergonic cleavage of the N-N bond and limitation of the ligand exchange step via a dissociative mechanism at the end of the cycle to only one possible pathway. A major aspect of the failure of the vanadium complex to mediate the reduction of N(2) to ammonia is the fact that the protonation steps involve major barriers, which cannot be surmounted thermally. Moreover, unlike molybdenum, the associative mechanism with vanadium triamidoamine complex is not likely to operate during the NH(3)/N(2) exchange step.

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“…Based on the experimental studies and the literature support, 22 a plausible mechanistic pathway is proposed (Scheme 4). A series of control experiments were carried out with the observed intermediates in order to obtain a clear insight into the mechanism associated with this process.…”

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confidence: 99%

Ammonia synthesis by the reductive N–N bond cleavage of hydrazine using an air-stable, phosphine-free ruthenium catalyst

Mohanty,

Rout,

Dandela

et al. 2024

Chem. Commun.

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Theoretical study on the mechanism of catalytic reduction of hydrazine to ammonia mediated by vanadium (III) thiolate complexes

Cited by 4 publications

References 28 publications

Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [Mo^HIPTN₃N] Catalyst

Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [Mo^HIPTN₃N] Catalyst

Why Vanadium Complexes Perform Poorly in Comparison to Related Molybdenum Complexes in the Catalytic Reduction of Dinitrogen to Ammonia (Schrock Cycle): A Theoretical Study

Ammonia synthesis by the reductive N–N bond cleavage of hydrazine using an air-stable, phosphine-free ruthenium catalyst

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Theoretical study on the mechanism of catalytic reduction of hydrazine to ammonia mediated by vanadium (III) thiolate complexes

Cited by 4 publications

References 28 publications

Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [MoHIPTN3N] Catalyst

Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [MoHIPTN3N] Catalyst

Why Vanadium Complexes Perform Poorly in Comparison to Related Molybdenum Complexes in the Catalytic Reduction of Dinitrogen to Ammonia (Schrock Cycle): A Theoretical Study

Ammonia synthesis by the reductive N–N bond cleavage of hydrazine using an air-stable, phosphine-free ruthenium catalyst

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Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [Mo^HIPTN₃N] Catalyst

Free Reaction Enthalpy Profile of the Schrock Cycle Derived from Density Functional Theory Calculations on the Full [Mo^HIPTN₃N] Catalyst