The structure of triphenylmethyl perchlorate at 85°C

Abstract

At 85 °C triphenylmethyl perchlorate crystallizes in space group F4132 with Z = 16 and a = 18.91 A. Most atoms lie on special positions. The structure was refined by three-dimensional :Fourier methods and least-squares techniques. The carbonium ion is propeller-shaped with three coplanar central bonds (symmetry Da). Adjacent aromatic rings are at angles of 54 °. There are two structurally different perchlorate groups; one is disordered, the other is not. The refinement was carried out for two models of disorder, leading to R values of 9.1 and 8.4 % respectively. Neither model is entirely satisfactory. Bond distances and bond angles are reported. It is shown in an appendix that triphenylmethyl tetrafluoroborate at 110 °C is isomorphous with the perchlorate.