Microwave spectrum, structure, and pgr; conjugation of isocyanocyclopropane

摘要

The microwave spectrum of the normal isotopic species of isocyanocyclopropane and its three unique monohyphen;substituted13C isotopic varieties have been investigated in their natural isotopic abundances. For the normal isotopic species, Stark modulation and RFMDR techniques lead to the following rotational constants:A=15thinsp;827.303plusmn;0.009 MHz,B=3734.004plusmn;0.002 MHz, andC=3515.892plusmn;0.002 MHz. These data, along with those for the three isotopic species, lead to the following heavy atom structural parameters: C1C2=1.521plusmn;0.007 Aring;, C2C3=1.513plusmn;0.005 Aring;, C1N=1.377plusmn;0.008 Aring;, and Cequiv;N=1.176plusmn;0.005 Aring;. To within a precision of plusmn;1deg;, the Cndash;Nequiv;C group is linear and is inclined at an angle of 123.4plusmn;0.6deg; to the plane of the ring. The structural parameters are compared to those of related molecules and interpreted in terms of a frontier molecular orbital model for the pgr; conjugation of the cyclopropyl ring.