Abstract
The molecular structure of cis- and trans-bicyclo [4.4.0] decane was studied in the gas phase. Molecular mechanics calculations applying Lifson's and Boyd's force fields were used to estimate the structural parameters and to calculate the vibrational amplitudes. The two isomers are in the “all chair” conformation. The trans-com pound has an inversion centre (midway between the junction atoms). The cis-isomer has a twofold axis of symmetry, passing through the centre of the junction at right angle to the bond in a plane bisecting the dihedral angle of the adjacent hydrogen atoms. The following geometrical parameters were obtained ( r a-structure): Cis, r(C-C) av = 1.530 Å. The average endocyclic valency angle is 111.4°, and the average torsional angle is 55.0°. The “connection angle” equals 128.1°. It is defined as the angle between the two planes bisecting respectively the torsion angles C7-C6-C1-C10 and C5-C6-C1-C2. Trans. r(C-C) av = 1.530 Å. The average endocyclic valency and torsional angles are respectively 111.4 and 55.0°. The “connection angle” is 180° ( C 2h-symmetry).
Published Version
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