Microwave spectra and structures of some 1-halogenoadamantanes

Abstract

The microwave spectra of the 1-halogenoadamantanes, C₁₀H₁₅X where X = F, Cl, and Br, have been observed and measured. The spectra exhibit the characteristics of symmetric-top molecules with the following rotational constants: B= 1159·877 ± 0·01, 836·432 ± 0·01, 817·520 ± 0·01, 557·765 ± 0·005, and 551·852 ± 0·005 Mc./sec. when X = F, ³⁵Cl, ³⁷Cl, ⁷⁹Br, and ⁸¹Br respectively.

With the assumption that all angles are tetrahedral and all C–H bond lengths are 1·09 Å, the chloride and bromide spectra give r_C-C= 1·541 ± 0·001 Å and 1·542 ± 0·003 Å respectively. Carbon–halogen distances. r_C-X, are 1·370 ± 0·004, 1·790 ± 0·002, and 1·947 ± 0·006 Å for X = F, Cl, and Br.