Molecular-orbital calculations surface

Ab initio molecular orbital calculations are being used to study the reactions of anionic nucleophiles with carbonyl compounds in the gas phase. A rich variety of energy surfaces is found as shown here for reactions of hydroxide ion with methyl formate and formaldehyde, chloride ion with formyl and acetyl chloride, and fluoride ion with formyl fluoride. Extension of these investigations to determine the influence of solvation on the energy profiles is also underway the statistical mechanics approach is outlined and illustrated by results from Monte Carlo simulations for the addition of hydroxide ion to formaldehyde in water. 

Acyclic phosphazenes (phosphazo derivatives, phosphine imines, phosphoranimines) continue to attract interest. A review of the three coordinate materials, RN=PR =X has appeared. " Several molecular orbital calculations have been reported. An ab initio treatment of the PN energy surface suggests that this species is best regarded as having a dative phosphorus-nitrogen double bond rather than a triple bond and the phosphonitrene, once formed,... 

Weiske, T. Koch, W. Schwarz, H. Experimental Evidence for the Existence of the Protonitronium Dication (H0N02+) in the Gas Phase and ab Initio Molecular Orbital Calculations of Its Potential Energy Surface. J. Am. Chem. Soc. 1993,115, 6312-6316. 

Fu et al. [16] analyzed a set of 57 compounds previously used by Lombardo and other workers also. Their molecular geometries were optimized using the semiempirical self-consistent field molecular orbital calculation AMI method. Polar molecular surface areas and molecular volumes were calculated by the Monte Carlo method. The stepwise multiple regression analysis was used to obtain the correlation equations between the log BB values of the training set compounds and their structural parameters. The following model was generated after removing one outlier (Eq. 50) ... 

Further support for structure 7a is obtained by AMI molecular orbital calculations performed on the reaction of C o and silylenes (Ph2Si ). These calculations show that Ph2Si adds across the junction of two six-membered rings in Cgo to give the 1,2-addition silirane analogous to 7a with an exothermicity of 61.3 kcalmol-1. The analog of 7b was not located on the potential energy surface. Also, 7a was 19.4 and 10.7 kcalmol-1 more stable than the 1,6-adducts 11a and lib, respectively (Scheme 4). 

In summary, the existence of these three different structure types suggests a rather delicate balance between the different minima on this interesting potential energy surface. Molecular orbital calculations at the highest levels currently practical are certainly quite useful in elucidating the nature of these structures. This is also an area where one may safely predict continuing efforts and where we anticipate additional insights by both ESR and CIDNP spectroscopy. 

In order to investigate the mechanism of S03 electrolysis, it was necessary to evaluate the electronic states of S03 adsorbed on Pt surface. For this purpose, by using the molecular orbital calculation with cluster models, we have evaluated the electronic states of S03 adsorbed on Pt (111) surface. Also, in order to... 

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