MICROWAVE SPECTRUM OF THE CIS CONFORMER OF CYCLOPROPANECARBOXYLIC ACID CHLORIDE

Abstract

The microwave spectrum of cyclopropanecarboxylic acid chloride has been observed and the transitions arising from the cis conformer with a bisected conformation have been assigned. Both $Cl^{35}$ and $Cl^{37}$ species have been identified. The ground state rotational constants are (in MHz) $A = 6541.77 \pm 0.05, B = 1796.675 \pm 0.007, C = 1583, 898 \pm 0-007$ for $CH_{2}CH_{2}CHCl^{35}$ and $A = 6512.78 \pm 1.0, B = 1755.147 \pm 0.008, C=1549.737 \pm 0.008$ for the $CH_{2}$ $CH_{2}CHCOCl^{37}$ species. From the planar moment, a shortening of the ring C-C bond opposite the point of substitution has been observed, providing additional evidence for variation of ring dimensions due to interaction with substituents having $\pi$ bonds which can conjugate with the ring.