Average Structures of t-Butyl Chloride and 9D-t-Butyl Chloride Determined by Gas-Phase Electron Diffraction

Abstract

The structure of t-butyl chloride has been determined by electron diffraction. The results obtained are in good agreement with the previous structure determination by Momany, Bonham, and Druelinger. This structure is shown to be consistent with the microwave rotational constants determined by Lide and Jen in spite of the fact that the rg distance for the C–Cl bond (1.828±0.005 Å) is quite different from the rs microwave distance (1.803±0.002 Å). The remaining structural parameters were determined to be C–C (1.528 Å), C–H (1.102 Å), ∠ ClCC (107.3o), ∠ CCH(110.8o), ∠CCC (111.6o), and ∠ HCH (108.1o). A simultaneous investigation of the structure of the deuterated species suggests slight secondary isotope effects on the C–C (ΔC–C=0.0010±0.0007-Å) and C–Cl (ΔC–Cl=0.0010±0.0015-Å) distances. Observed mean amplitudes of vibration are found to be consistent with values calculated from the harmonic force field of Hüttner and Zeil.

Molecular Structures of Trimethylchlorogermane, (CH3)3GeCl, and Trimethylbromogermane, (CH3)3GeBr, Obtained by Gas-Phase Electron Diffraction and Theoretical Calculations

“…For F-, Cl-, and Br-substituted germanium compounds, the Ge-C and Ge-X distances increase as the numbers of F, Cl, or Br atoms decrease. This finding was also observed for the silicon compounds, (CH 3 ) 4-n SiCl n 10-13 (n ) 0-4), and similar changes were reported for the carbon analogues (CH 3 ) 4-n CCl n [14][15][16][17] (n ) 0-4). The trend can be rationalized by the dual effects of "crowding" of the methyl groups and/or the increasing positive charge on the C, Ge, or Si atoms that results from the increasing degree of halogenation in the molecules.…”

Molecular structure and conformational composition of 1-Chlorobutane, 1-Bromobutane, and 1-Iodobutane as determined by gas-phase electron diffraction and ab initio calculations

“…Calculation of vibrational amplitudes (l), perpendicular amplitude corrections (K), and centrifugal distortion constants (6r) were carried out by normal coordinate analysis [32], using valence force fields where the force constants were taken from related molecules and from molecular mechanics (MM) calculations [33,34]. From results obtained in earlier investigations of halogenated alkanes it is reasonable to assume threefold barriers against torsion about each of the three carbon-carbon bonds.…”

.pi.-Interactions in the structures of 1- and 2-methylpentaborane and 1- and 2-silylpentaborane. Electron diffraction study

“…The amplitudes of vibration and shrinkage effects were calculated using a method described in detail elsewhere. 25 The long and short camera distance data were leveled, spliced together, and analyzed by differential least squares.…”