An X-ray diffraction determination of the structure of N-ethyl-2,2,4,4,6,6-hexaphenyl-3-azacyclotrisiloxane

Abstract

A three-dimensional X-ray diffraction analysis of an azacyclotrisiloxane has been completed. The crystals are monoclinic, space group P2₁/a, with a= 17·412, b= 16·287, c= 13·725 Å, β= 116° 31′. The solution to the structure was obtained by direct methods with a ratio of reflexions to atoms of less than 5 : 1. Positional parameters and individual isotropic temperature factors were refined until R reached a final value of 12·5% for 2337 independent reflexions. Anomalous lengths were obtained in the ethyl group for a reason which is not known, but other molecular parameters are close to standard or expected values. The central six-membered ring adopts a distorted boat form.