Molecular mechanics-based measures of steric effects: Customized code to compute Ligand repulsive energies

Understanding the Steric Control of Stereoselective Olefin Binding in Cyclopentadienyl Complexes of Rhenium: An Application of de Novo Ligand Design

“…15,17,27,28 Subsequently, Brown and others have computed ligand repulsive energies with a variety of different ligands in a series of different prototypical environments using two different force fields (MMP2 and UFF). 2,18,22,24,25,29,30 In general, ligand repulsive energies show the same trend irrespective of either fragment or force field used for their computation. 18,22,24,25,29 In this paper, we apply the ligand repulsive energy methodology to the computation of the steric interaction between prochiral R-olefins, CH 2 dCHR (R ) Me, n-Pr, CH 2 Ph (Bn), Ph, i-Pr, t-Bu, and SiMe 3 ), 14 and the chiral organometallic fragments, [CpRe(NO)(L)] + and [Cp*Re-(NO)(L)] + (L ) PPh 3 , PMe 3 ; Cp* ) η 5 -C 5 Me 5 ).…”

“…2,18,22,24,25,29,30 In general, ligand repulsive energies show the same trend irrespective of either fragment or force field used for their computation. 18,22,24,25,29 In this paper, we apply the ligand repulsive energy methodology to the computation of the steric interaction between prochiral R-olefins, CH 2 dCHR (R ) Me, n-Pr, CH 2 Ph (Bn), Ph, i-Pr, t-Bu, and SiMe 3 ), 14 and the chiral organometallic fragments, [CpRe(NO)(L)] + and [Cp*Re-(NO)(L)] + (L ) PPh 3 , PMe 3 ; Cp* ) η 5 -C 5 Me 5 ). Ligand repulsive energies computed with the Cr(CO) 5 fragment are given the label E R , and other ligand repulsive energies are called E R Force field (fragment).…”

In Silico Design in Homogeneous Catalysis Using Descriptor Modelling

“…The ligand repulsive energy (E R ) method can answer this question. [60] This methodology relies on quantifying the van der Waals repulsive energy variation as a function of the ligand-metal/complex distance (eq 1). In this equation E vdW is the pure repulsive form of the vdW potential and r e is the bond length between the metal and the ligating atom on a ligand (the negative sign ensures that as the steric bulk of the ligand increases, E R also increases).…”

A Gas-Phase Study of the Kinetics of Formation of Fe(CO)3DMB, Fe(CO)3(DMB)2, and Fe(CO)4DMB: The Bond Dissociation Enthalpy for Fe(CO)3(DMB)2 (DMB = 3,3-dimethyl-1-butene)

“…For example, the shapes of η 2coordinated olefins are sufficiently far removed from conical to render the cone angle methodology ineffective as a measure of alkene size. 24 The ligand repulsive energy parameter, E R , defined in terms of the change in the van der Waals repulsive energy with distance, or an analogue of this parameter would be expected to be a more reasonable measure of steric interactions. 24,25 In this work we employ a semiquantitative measure of the effect of the size and shape of a ligand on bonding interactions.…”

“…24 The ligand repulsive energy parameter, E R , defined in terms of the change in the van der Waals repulsive energy with distance, or an analogue of this parameter would be expected to be a more reasonable measure of steric interactions. 24,25 In this work we employ a semiquantitative measure of the effect of the size and shape of a ligand on bonding interactions. The steric repulsive energy, which is qualitatively similar to E R , was calculated using the Tripos force field, available in the Sybyl molecular mechanics program.…”