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 P21/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 C11(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.