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Conformation of tripod Metal Templates in CH 3 C(CH 2 PPh 2 ) 3 ML n ( n = 2, 3): Neural Networks in Conformational Analysis
Author(s) -
Beyreuther Stefan,
Hunger Johannes,
Huttner Gottfried,
Mann Susanne,
Zsolnai Laszlo
Publication year - 1996
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19961290704
Subject(s) - tripod (photography) , chemistry , template , crystallography , metal , stereochemistry , physics , nanotechnology , optics , organic chemistry , materials science
The conformational space spanned by tripod metal templates CH 3 C(CH 2 Ph 2 ) 3 M is analysed on the basis of the solid‐state structures of 82 tripod Co templates in compounds tripod CoL 2 and tripod CoL 3 . Systematic analysis, including the techniques of conformational space group scatter graphs, principal‐component analysis, and partial least squares, reveals a series of basic regularities: The torsion of the phenyl groups is strongly linked to the torsional skew of the bicyclooctane‐type framework of the chelate cage. For one sense of this skew there are two classes of low‐energy conformation that differ by the helicity of the phenyl arrangement and by the degree of torsional skew in the chelate backbone. From the scatter graphs it is evident that a change in helicity may occur by one‐ or by two‐ring flip mechanisms. The basic regularities found by the above methods are also evident from the analysis of the same data by a neural network approach. The fact that these regularities are found for tripod CoL 2 and tripod CoL 3 , irrespective of the widely different coligands L and crystal environments, means that the conformation of the tripod metal templates is governed by the forces acting within them and not so much by the forces imposed on them by their individual chemical or crystal environment. It is shown that the classifications, although derived from a data basis only containing Co compounds, are characteristic for tripod metal templates irrespective of the specific metal involved.