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Synthesis, kinetics and mechanism of nucleophilic substitution in octahedral (cat)2Sn(py)2

Siddiqi K.S. (Department of Chemistry, Aligarh Muslim University, Aligarh, India)
Nami Shahab A.A. (Department of Chemistry, Aligarh Muslim University, Aligarh, India)

Dicatecholatodipyridinetin(IV) in nitrobenzene showed an increase in molar conductance with time, suggesting solvation of the complex. In the presence of nucleophilic reagents, such as SOCl2, C6H5COCl and CH3COCl, the conductance increased sharply owing to the substitution of pyridine by chloride ions. The data for the rate constant of solvation (k s) and for nucleophilic substitution (k 1 and k 2) have been calculated and it was found that the solvation is a slower process compared to the substitution by chloride ions, i.e., k1, k 2 > k s. The nucleophilic substitution reaction follows the SN1 mechanism.

Keywords: molar conductance, solvation, nucleophiles, nitrobenzene