Molecular mechanics (MM3) studies of monochloroalkanes

Abstract

Monochloroalkanes were studied using molecular mechanics and parameters were developed and incorporated into MM3. The new force field reproduces well molecular structures, conformational energy differences and vibrational frequencies. The compounds studied were methyl, ethyl, n‐propyl, isopropyl, n‐butyl, isobutyl, sec‐butyl, tert‐butyl, neopentyl, cyclopentyl and cyclohexyl chloride, 4‐tert‐butyl‐1‐chlorocyclohexane and 1‐chloroadamantane. The overall rms error for the averaged C—C and C—Cl bond lengths for the above set of compounds excluding sec‐butyl chloride, neopentyl chloride and 1‐chloroadamantane is 0·0047 Å, and the rms error for the vibrational frequencies is 377thinsp;cm−1. The moments of inertia (rg) are approximately 1% greater than the microwave values (ra0). Thermodynamic quantities are also compared with those observed using various experimental methods. © 1997 John Wiley & Sons, Ltd.

Studies on the Solvolytic Reactivity of Tertiary Chloroalkanes in Hexafluoro-2-propanol by ab Initio and Force Field Calculations

“…Both MM3 force field and ab initio calculations with the RHF/6-31G* basis set indicated good agreement with experimental data for chlorides 1 − 3 . , Therefore, similar calculations for chlorides 1 − 10 and corresponding carbenium ions were carried out. The strain energies were calculated by using the MM3(94) program.…”

Molecular Mechanics (MM3) Conformational Studies of Cyclic and Acyclic Monochloroalkanes

“…A recently developed MM3 monochlorohydrocarbon force field usually reproduces to within experimental error molecular structures . The overall root mean square (rms) error for the averaged C−C and C−Cl bond lengths for a large set of compounds excluding sec -butyl chloride, neopentyl chloride, and 1-chloroadamantane was 0.004 Å, and the rms error for the vibrational frequencies was 37 cm -1 .…”

Anharmonic Molecular Mechanics: Ab Initio Based Morse Parametrizations for the Popular MM3 Force Field

“…First a test set of molecules was created and MM3 atoms types were assigned to each species. This test set primarily included molecules that were used to parametrize the existing MM3 parameters as described in various publications; − however, it was necessary to add a substantial number of additional molecules in order to cover a larger selection of the MM3 bonding types. This test set is listed in the online Supporting Information.…”