CRYSTAL-STRUCTURE OF (BENZOTRIAZOLATO)THALLIUM(I) AND ITS RELATION WITH THE MECHANISM OF CORROSION INHIBITION BY BENZOTRIAZOLE

The crystal and molecular structure of (benzotriazolato)thallium(I) is described. The structure has been determined by using three-dimensional X-ray diffraction data collected by counter methods. Crystal symmetry is consistent with the monoclinic space group C2/c. The unit cell parameters are a = 26.605 (3) A, b = 4.057 (1) A, c = 12.173 (2) A, 0 = 93.74 (1)A. and Z = 8; = 3.268 g/cm3 and (Mo Ka) 246.8 cm1. The structure was solved by Patterson and subsequent Fourier techniques. Full-matrix least-squares refinement converged to RF = 0.022 and RvF = 0.024 for 1297 reflections. The structure consists of sheets of T1(I) ions separated by benzotriazole anions. Each T1 ion is coordinated by three N atoms of the ligand at distances of 2.725-2.792 A and by three neighboring N atoms at 3.271-3.326 A in a distorted trigonal-prismatic geometry. Tl-Tl distances in the sheet are 3.592, 3.679, and 4.057 A. The T1 ions are arranged in zigzag chains in the metallic layers. The layers are completely separated by the benzotriazole anions, which are packed very closely together and are directed with all N atoms to the T1 layer. The structure of the layers is similar to that predicted for the protective layer formed when metal surfaces (i.e., copper) are treated with the corrosion inhibitor benzotriazole. © 1979, American Chemical Society. All rights reserved.