Normal Vibrations of the Polymer Molecules of Helical Conformation. VI. Polytetrahydrofuran and Deuterated Polytetrahydrofurans

Polarized infrared spectra of polytetrahydrofuran, polytetrahydrofuran-3,3,4,4-d4, and polytetrahydrofuran-d8 have been measured in the region from 4000 to 400 cm−1. The selection rules for polytetrahydrofuran molecule are derived under the factor group isomorphous to D2h. The normal vibrations of these polymer molecules are calculated for the infrared active B1u, B2u, and B3u species, by the use of the GF matrix method with the Urey-Bradley force field. The results show fairly good agreement of the observed and calculated frequencies, and give support to the 21 helix conformation, i.e., the planar zigzag conformation, reported previously. The assignments of the bands are given and discussed.