A method to measure the size of phosphorus ligands in coordination complexes

Immirzi, A.; Musco, A.

doi:10.1016/s0020-1693(00)95635-4

Cited by 99 publications

(65 citation statements)

References 16 publications

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“…[4] We now report on mechanistic aspects of the reaction of the amide complex 1a with HCOOH leading to the formato-amine complex, Ru(OCHO)[(R,R)-TsNCHPhCHPhNH 2 )](h 6 -p-cymene) (3a), [3c,5] which is readily decarboxylated to give the hydrido-amine complex 2a and CO 2 , and the reverse reaction of the hydride complex 2a with CO 2 . [6] This is the first experimental demonstration of the NH-assisted formal CO 2 insertion into the Ru À H bond.…”

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confidence: 82%

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Mechanistic Aspects of Formation of Chiral Ruthenium Hydride Complexes from 16‐Electron Ruthenium Amide Complexes and Formic Acid: Facile Reversible Decarboxylation and Carboxylation

2004

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Abstract:The 16-electron amide complex, Ru[(R,R)-TsNCHPhCHPhNH](h 6 -p-cymene) (Ts p-toluenesulfonyl, Ph C 6 H 5 ) readily reacts with formic acid to give the corresponding formate complex, which subsequently undergoes decarboxylation leading to the hydride complex with release of CO 2 . The reaction of this hydride complex with CO 2 under mild reaction conditions, a pressure of 10 atm and even at À 78 8C, proceeds rapidly to give the corresponding formate complex almost quantitatively. Thus, the reversible decarboxylation and carboxylation takes place with or without the aid of a metal-NH bifunctional effect of the Ru complexes.

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confidence: 82%

“…Based on the kinetic data involved with the negative entropy value, there are three possible pathways for the decarboxylation: formato anion dissociation leading to an ion pair (5), [9] (2)ÀC (2), 112.5 (6). Priority for the assignment of absolute configuration at Ru: p-cymene > OCOCH 3 > NTs > NH 2 .…”

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confidence: 99%

Mechanistic Aspects of Formation of Chiral Ruthenium Hydride Complexes from 16‐Electron Ruthenium Amide Complexes and Formic Acid: Facile Reversible Decarboxylation and Carboxylation

2004

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“…The minimum energy conformer was finally minimized using a convergence gradient of 0.001 kcal mol Ϫ1 Å Ϫ1 . Cone angles for the axial ligands were calculated according to the ImmirziЈs algorithm, [33] as modified in ref. [21] , using the atom coordinates of the 52 energy minimized structures.…”

Section: Introductionmentioning

confidence: 99%

A Molecular Mechanics Force Field for Alkylcobaloximes, a Model of Vitamin B12 Coenzyme – Implications of Steric and Electronic Factors in the Co–C Bond Cleavage

Geremia

Calligaris

Randaccio

1999

Eur. J. Inorg. Chem.

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Molecular mechanics force field constants have been derived for alkylcobaloximes, (alkyl)Co(DH)2L (DH = monoanion of dimethylglyoxime and L = planar N‐donor ligand), implementing the AMBER force field. Atomic charges have been calculated by the semiempirical ZINDO/1 method. Stretching and bending constants have been calculated by the Badger and Halgren equations, with the introduction of simple functions for the description of the electronic influence of the axial ligands on the coordination geometry. 26 parameters have been optimized, by the Simplex method, to fit 4523 bond lengths and angles of 52 alkylcobaloxime accurate crystal structures. In spite of the oversimplification of the adopted method for the description of the electronic effects, this approach provides a good description of the metal coordination geometries. The root‐mean‐square deviations of the calculated bond lengths and angles from the experimental values average to 0.023 Å and 1.4°, respectively. The molecular mechanics results are discussed in terms of the steric properties of the axial ligands and correlated with their calculated cone angles. The force field has been used to analyse some conformational features of these compounds, such as the influence of the rotation of the axial ligands on their coordination geometry. The calculated energy for the Co–N rotational barrier agrees well with the experimetal ones derived from dynamic and saturation 1H‐NMR spectroscopy in (alkyl)Co(DH)2(2‐NH2‐py). In order to have more experimental data for this analysis, the crystal structures of two new cobaloximes, (CH2Cl)Co(DH)2L with L = py, 1, and 1‐Me‐Im, 2) have been determined. The results of a conformational analysis on ribosyl‐imidazole derivatives, taken as a suitable vitamin B12 coenzyme model, suggest that the 1‐Me‐imidazole‐like ligands have a significantly greater rotation freedom with respect to the benzimidazole‐like ones, but cause similar stretchings of the Co–C bond, and a significantly less stretching of the Co–N one. Implications for the recent findings on the binding mode of the coenzyme B12 in the enzyme active site are discussed.

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“…These elaborations include mathematical methods, [24,25] calculations based on X-ray structural data, [17,[26][27][28] and solid cone angle measures. [29][30][31][32][33][34][35][36][37][38] White et al wrote a program (Steric®) for calculating the steric size of molecules around a point (e.g. the metal atom) or by projection on a directional area (e.g.…”

Section: D-descriptorsmentioning

confidence: 99%

In Silico Design in Homogeneous Catalysis Using Descriptor Modelling

Burello

Rothenberg

2006

IJMS

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This review summarises the state-of-the-art methodologies used for designing homogeneous catalysts and optimising reaction conditions (e.g. choosing the right solvent). We focus on computational techniques that can complement the current advances in highthroughput experimentation, covering the literature in the period 1996-2006. The review assesses the use of molecular modelling tools, from descriptor models based on semiempirical and molecular mechanics calculations, to 2D topological descriptors and graph theory methods. Different techniques are compared based on their computational and time cost, output level, problem relevance and viability. We also review the application of various data mining tools, including artificial neural networks, linear regression, and classification trees. The future of homogeneous catalysis discovery and optimisation is discussed in the light of these developments.

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A method to measure the size of phosphorus ligands in coordination complexes

Cited by 99 publications

References 16 publications

Mechanistic Aspects of Formation of Chiral Ruthenium Hydride Complexes from 16‐Electron Ruthenium Amide Complexes and Formic Acid: Facile Reversible Decarboxylation and Carboxylation

Mechanistic Aspects of Formation of Chiral Ruthenium Hydride Complexes from 16‐Electron Ruthenium Amide Complexes and Formic Acid: Facile Reversible Decarboxylation and Carboxylation

A Molecular Mechanics Force Field for Alkylcobaloximes, a Model of Vitamin B12 Coenzyme – Implications of Steric and Electronic Factors in the Co–C Bond Cleavage

In Silico Design in Homogeneous Catalysis Using Descriptor Modelling

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