Molecular mechanics (MM4) force field development for phosphine and its alkyl derivatives

Abstract

Based on the experimental structures and vibrational spectra of eight alkylphosphines, as well as ten ab initio calculated (MP2/6-31+g*) structures and five potential energy profiles, the MM4 force field has been extended to include this important functional group. The results are comparable to experimental values for phosphorus-containing compounds. The addition of various cross-terms significantly improved the MM4 calculated structures relative to its predecessor, MM3. The overall root mean square error in moments of inertia have been reduced from 1.65% in MM3 to 0.26% in MM4. MM4 was also successful in reducing the previously impressive root mean square error in vibrational frequencies from 35 cm(-1) to 31 cm(-1) for the eight compounds studied.

Adsorption and Binding of Ligands to CdSe Nanocrystals

“…This force field is known to accurately reproduce properties of (multicomponent) liquids and vapors. Parameters for the phosphorus and oxygen containing headgroup of TBPO are taken from the MM3 force field as in ref ; the ones for TBP are taken from its successor (MM4 force field) . These parameters were developed to reproduce the geometry of isolated molecules; we are not aware of any force field for phosphines or POs that was designed or tested for bulk compounds.…”

“… a Reference . b Reference . c Reference . d Reference . e Reference . f Reference . g The charge of S − was defined by removing a proton of an SH group using the TraPPE force field. …”

“…Parameters for the phosphorus and oxygen containing headgroup of TBPO are taken from the MM3 force field 38 as in ref 32; the ones for TBP are taken from its successor (MM4 force field). 39 These parameters were developed to reproduce the geometry of isolated molecules; we are not aware of any force field for phosphines or POs that was designed or tested for bulk compounds. LJ cross parameters are obtained using the Lorentz-Berthelot mixing rules.…”

A molecular mechanics approach to mapping the conformational space of diaryl and triarylphosphines

“…8a, b The MM component has been applied using a variety of common MM force fields which have not been ideally parameterised to deal with arylphosphines, though a parameterisation for alkyl phosphines has recently been reported. 9 Other recent approaches have identified various metal-ligand descriptors which may be used to correlate the steric and electronic properties of phosphine ligands. 10a-c We report here the testing of an adapted MM force field for triaryl and alkyldiaryl phosphines and their chalcogenide and Cr(CO) 5 derivatives which can be incorporated into standard computational packages as an aid in the design of phosphines and phosphine complexes for use in catalysed organic synthesis.…”

Molecular mechanics (MM4) study of amines

“…In principle, the effect will also occur with a second row atom (or higher) as the electron pair donor, and it will also occur when the atom attached at the position is other than hydrogen, but such cases have not yet been studied in much detail. 6,36 The 26 -CÀ ÀH stretching vibrations (double counting the observed E vibrations) calculated by MM4 after including the appropriate torsion-stretch interactions (Supplementary Table S1) for six small representative amines have a rms error of 22 cm À1 (Table1). For this set of compounds, some -hydrogens have torsion angles near 1808, and others near 608, to the lone pair.…”