The microwave spectra of C13H3CH2Cl35, CH3C13H2Cl35, CH3CD2Cl35, and CH2DCH2Cl35 have been examined and rotational constants assigned. Both a-type and b-type spectra have been observed. From these spectra and those previously reported for CH3CH2Cl35, CH3CH2Cl37, and CH2DCH2Cl35 a complete structure has been obtained by means of the substitution method. The bond distances and bond angles obtained are as follows: CC = 1.520 A, CCl = 1.788 A, CH (methyl) = 1.091 A, CH (methylene) = 1.089 A, CCCl = 111°2′, HCH (methyl) = 108°30′, HCH (methylene) = 109°12′, CCH (methylene) = 111°36′. The quadrupole coupling parameters and barrier to internal rotation have been re-evaluated in terms of the above structure. The quadrupole coupling parameters are χbond = —68.80 Mc and ηbond = 0.035, if the angle between the a axis and the CCl bond is determined from the structure; or χbond = —71.24 Mc, if a cylindrical charge distribution is assumed near the chlorine nucleus. The barrier to internal rotation is 3685 cal/mole.

Articles you may be interested inMicrowave spectrum and ring structure of cyclopropyl cyanideThe pure rotational microwave spectra of seven isotopic species of cyclopropyl chloride have been examined and rotational constants assigned. The data are sufficient for a complete structure determination by the substitution method. The bond distances and bond angles obtained are r (C1C2) = 1.513 A, r(C2Ca) = 1.515 A, r(CCl) =1.740 A, average r(CH) =1.08 A, LCCCI=118.7°, LCICH=115.8°, and LHCH= 116.2°. The quadrupole coupling constants of C a H s Cl3s in the principal inertial axis system are Mc/sec, xbb=36.72 Mc/sec, and xcc=19.92 Mc/sec. These values are consistent with x .. and '1bond =0.029 if the z axis and the CCI internuclear line are assumed to coincide, and with x .. = -73.5 Mc/sec if the charge distribution near the chlorine nucleus is assumed to be cylindrically symmetric.

Observations of the microwave spectra of seven ground-state species and three first excited torsional state species of CH2ClSiH3 are reported. From an analysis of the moments of inertia of the various species structural parameters are deduced as follows: bond distances; CCl= 1.788 A, CSi= 1.889 A, CH= 1.096 A, SiH= 1.477 A, and bond angles; SiCCI= 109.3°, SiCH= 109.3°, HSiH= 110.6°, and HCH= 107S. An analysis of the hyperfine splitting leads to quadrupole coupling parameters XCCI bond= -68.7 Me, '1CCI bond=O.048, if it is assumed that the CCI bond direction forms one principal axis of the quadrupole tensor; and XCCI bond = -72.0 Mc if it is assumed that the quadrupole tensor is cylindrically symmetric. Analysis of splittings in the first excited torsional state indicate that the height of the potential barrier hindering internal rotation of the SiH3 group is 2.55 kcal/mole.

A Physical Chemistry Experiment on ClathratesOver the past several years we have been changing the emphasis in the physical chemistry laboratory course from one of many individual, sometimes unrelated, experiments, to one of fewer but more com-

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