Density functional and X-ray diffraction studies of two polymorphs of N,N′,N″-triphenylguanidine

The crystal structure of a new phase of triphenylguanidine has been solved by X-ray diffraction. The crystals are monoclinic, space group P 2 1 / c , with a = 12.4060(4) Å, b = 15.1653(6) Å, c = 8.7028(3) Å, β = 103.2482(15)°, Z = 4 and R = 0.0572. The crystal structure of the common orthorhombic phase of triphenylguanidine has been redetermined. The hydrogen bond patterns, in both polymorphs, delineate chains with C 1 1 ( 4 ) as the graph descriptor. Both crystal structures were optimized using Density Functional Theory within the Local-Density Approximation. The monoclinic phase is less stable, with an energy minimum 79.0 kcal/mol higher than the orthorhombic phase.