Template synthesis and structural characterization of new diorganotin(IV) tetraazamacrocyclic complexes: precursors to produce pure phase nanosized SnO_2

摘要

This article describes the synthesis and characterization of several new diorganotin(lV) tetraazamacrocyclic complexes. The template condensation of anthranilic acid and diethylene-triamine with 1,2-dibromoethane or 1,3-dibromopropane in the presence of diorganotin(IV) dichlorides yielded macrocyclic complexes. The geometry and the mode of bonding of the resulting complexes were inferred from elemental analysis, UV-Vis, 1R, Direct Analysis in Real Time-mass, (~lH, ~(l3)C and ~(119)Sn) NMR, and ~(119m)Sn Mossbauer spectral studies. These studies suggested that the macrocyclic ligands are tetradentate, coordinating through four nitrogens giving a skew-trapezoidal bipyramidal environment around tin in the [R_2Sn(L-l)/(L-2)] (R = Me, n-Bu and Ph; H_2L-l/H_2L-2 = macrocyclic ligands) complexes. Thermal studies of the complexes were carried out in the temperature range 25-1000 deg C using thermogravimetry, derivative thermogravimetry, and differential thermal analysis techniques which provided a simple route to nanosized semi conducting SnO_2 grains, identified by X-ray diffraction analysis. The particle size of the residue, obtained by pyrolysis of 2, 3, 4 and 5, determined by X-ray line broadening and transmission electron microscope were in the range approx 38-48 nm and approx 3-20 nm, respectively. The surface morphology of these residues was determined by scanning electron microscopy.