Molecular structure in the crystalline state of a dicarbonium ion containing two triphenylmethylium ion groups

Abstract

The X-ray analysis of the crystalline material C₃₈H₂₈Cl₁₂Sb₂ shows it to consist of a dicarbonium ion ([C₃₈H₂₈]²⁺), having two triphenylmethylium ions joined by a C–C bond through the para-positions of two of the phenyl rings, and two hexachloroantimonate anions. The crystals are monoclinic with a= 16·67(3), b= 12·81(3), c= 21·52(5)Å, and β= 105° 0′(20′), and there are four [C₃₈H₂₈]²⁺[SbCl₆^–]₂ entities in the unit cell; the space group is P2₁/c. The structure has been refined to R 0·10 for 3118 non-zero independent structure amplitudes collected photographically. The dicarbonium ion can be thought of as two triphenylmethylium ions separated by a biphenyl-like bond and each having a ‘propeller-like’ conformation around the plane defined by the central carbon atom and its three bonded neighbours; the phenyl rings make angles from 26·7 to 38·0° with the planes defined by the central carbon atoms and their bonded neighbours. The central biphenyl group has a dihedral angle of 39·5°. The shortest C⋯Cl^– contact is 3·42 Å.