MOLECULAR-STRUCTURE OF CYCLOHEPTANE - ELECTRON-DIFFRACTION STUDY

The molecular structure of cycloheptane (C7H14) has been investigated in the gas phase by electron diffraction. Diffraction intensities can be explained by a twist-chair/chair mixture with an abundance of 76(6)% for the twist-chair conformation at 310°K. Using the nomenclature of J. Cremer and J. A. Pople [J. Am. Chem. Soc. 97, 1354 (1975)] the puckering coordinates were found to be q2 = 0.529 Å, q1 = 0.645 Å for the twist-chair and q2 = 0.487 Å, q 3 = 0.715 Å for the chair form. Other geometrical parameters are: C-C= 1.538 Å, C-H=1.112 Å, ≮ C-C-C aver. = 115.3° (twist-chair) and 113.5° (chair). Experimental geometries and vibrational amplitudes agree well with those obtained from force field calculations. © 1979 American Institute of Physics.