THE MICROWAVE SPECTRUM AND STRUCTURE OF PROPYNAL $(H C=C CHO)$
Loading...
Date
1958
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
“The J2$\leftarrow$1 and J3$\leftarrow$2 (Type a) rotational transitions of nine isotopic species of propynal have been observed, yielding the rotational constants B and C. The molecule is planar, and by observing certain Type b transitions in the species HCCCHO and DCCCHO the rotational constant A and hence the inertial defect $\Delta$ could be calculated for these molecules. The value of $\Delta$ in HCCCHO was found to be 0.1715 a.m.u. $\bar{A}^{2}$, and in DCCCHO, 0.1783 a.m.u. $\bar{A}^{2}$. By assuming $\Delta$ to be unaffected by a $C^{12}$ substitution, two independent sets of molecular parameters were calculated. Quite satisfactory agreement was obtained without correcting for centrifugal distortion. The $H_{1}-C_{1}\equiv C_{2}-C_{3}$ chain was found to be bent very slightly at the central carbon away from the oxygen alom. The calculated structural parameters of the molecule are as follows: ${H}_{1}-{C}_{1}=1.0551 \AA\qquad {C}_{1}{C}_{2}=1.2088 \AA, \qquad {C}_{2}{C}_{3}=1.4449 \AA\\{C}_{a}{O}=1.2160 \AA, \qquad \leq {C}_{1}{C}_{2}{C}_{3}=1^{\circ} 42^{\prime} { and }\\\qquad \leq {C}_{2}{C}_{3}{O}=56^{\circ} 18^{\prime}$ No parameters for the aldehyde hydrogen are offered, as substitution at this position has so far not been possible.”
Description
Author Institution: Division of Pure Physics, National Research Council