Experimental electron density study of 1,2,4-triazole at 15 k. A comparison with ab initio-calculations

Topological properties and the Laplacian function of the electron density of 1,2,4-triazole have been determined from X-ray diffraction data collected at 15 K. 1,2,4-Triazole, C 2 H 3 N 3 , orthorhombic, space group Pbca, Z= 8, lattice parameters a = 9.717(4) A, b = 9.304(4) A and c = 6.912(4) A. The results are compared with those derived from ab initio-wavefunctions at the Hartree-Fock and MP2 level of theory. The different C-N bonds are analyzed in terms of bond topological parameters. The result reveals considerable aromaticity which seems to be enhanced by the strong hydrogen bonds.