How to Predict Conformations Accessible to a Molecule in Solution: Validation of a Force Field-Based Prediction of NOE Distances by Comparison with the Experimental Data for the Series of Compounds CH3C[CH2P(Bzl)R]3Mo(CO)3 (R = Ph, m-Xyl)
✍ Scribed by Stefan Beyreuther; Johannes Hunger; Sven Cunskis; Tammo Diercks; Axel Frick; Eckart Planker; Gottfried Huttner
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 809 KB
- Volume
- 1998
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Molybdenum(CO) 3 compounds / Conformational ensembles in solution / Modelling NOE contacts / MM2* Force field calculations / Packing forces
NMR-NOE analysis of the three compounds (RRS/SSR)-observed and calculated NOE distances is highly satisfactory in each case (rms = 0.2 A ˚to 0.3 A ˚). By a statistical analysis it CH 3 C(CH 2 PPhBz) 3 Mo(CO) 3
(1), (RRR/SSS)-CH 3 C(CH 2 -PPhBz) 3 Mo(CO) 3 (2), and (RRR/SSS)-CH 3 C[CH 2 P(m-Xyl)-is shown that the predictions made by applying this Boltzmann weighted force field approach are highly Bz] 3 Mo(CO) 3 (3), leads to experimental values for a number of intramolecular H•••H contacts in each case. By the very significant. There is only a chance of 3 in 100 000 that this quality of prediction might be obtained by chance. This is nature of the NOE method, and with the type of molecules studied here, these values have to be understood as a taken as a validation, albeit indirect, of the energy scale reproduced by the force field parameters as developed. The Boltzmann weighted average over all the conformations accessible to the molecules in solution. -A Boltzmann methods described give a detailed insight into the conformational flexibility of molecules of the type studied. weighted force field approach is used to predict these values on the basis of sets of force field parameters derived earlier Solid state structures of the molecules are also correctly modelled by the force field used. for this class of compounds. The agreement between