Thermal decomposition of diorganotin(IV) derivatives of macrocycles of general formula, R2Sn(L1) and R2Sn(L2) (where R = n-butyl (1/4), methyl (2/5), and phenyl (3/6); H2L1 = 5,12-dioxa-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,8-diene and H2L2 = 6,14-dioxa-8,16-dimethyl-1,5,9,13-tetraazacyclotetradeca-1,9-diene), provides a simple route to prepare nanometric SnO2 particles. X-ray line broadening shows that the particle size varies in the range of 36–57？nm. The particle size of SnO2 obtained by pyrolysis of 3 and 5 is in the range of 5–20？nm as determined by transmission electron microscope (TEM). The surface morphology of SnO2 particles was determined by scanning electron microscopy (SEM). Mathematical analysis of thermogravimetric analysis (TGA) data shows that the first step of decomposition of compound 4 follows first-order kinetics. The energy of activation ( ), preexponential factor (A), entropy of activation ( ), free energy of activation ( ), and enthalpy of activation ( ) of the first step of decomposition have also been calculated. Me2Sn(L2) and Ph2Sn(L1) are the best precursors among the studied diorganotin(IV) derivatives of macrocycles for the production of nanometric SnO2. 1. Introduction In recent years nanometric SnO2 is of current interest because of its semiconducting, optical, and electronic properties. In addition to these, tin(IV) oxide possesses potential applications such as catalytic supports [1, 2], transparent conducting electrodes [3], and gas sensors [4, 5]. SnO2 is preferred over other metal oxides in gas sensors because of its high sensitivity and selectivity for different gases (e.g., H2) in mixture [6]. Nanometric SnO2 has different properties from bulk crystals; therefore, much attention has been addressed to synthesis and characterization of such materials. To produce nanometric SnO2, a variety of chemical and physical methods [7–11] have been reported in the literature. Tetraazamacrocycles and their derivatives have drawn special attention because of their applications in various fields such as analytical, industry, medicinal, and biological [12–16]. A thorough survey of literature reveals that only a few attempts have been made to study the thermal stability of metal complexes of tetraazamacrocycles [17]. However, a considerable attention has been given to the thermal decomposition of organometallic compounds in the last few years because they decompose at low temperature producing metallic oxides/sulfides and metallic particles. A thorough survey of literature reveals that limited studies have been carried out
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