Ionic Reactions in Thionyl Chloride. Part III. Nature of Thionyl Chloride in certain Acid-base Complexes of Pyridine

Studies on molar conductance of the complexes, (C5H5N)2MCI4.SOI2(M is tin or titanium) and (C5H5N)2. SnCI4 in nitrobenzene indicate that the former class behaves as uni-univalent electrolytes and, constitution of these may be suggested as (C5H5NSOCI)+ (C5H5NMIC15)— which does not violate hexa-covalencycy of titer titanium, The addition of thionyl chloride to the nitrobenzene solutions of all the three complexes converts them into uni-bivalent electrolytes since chloride ion, being a strong nucleophile, displaces pyridine. On the basis of available evidence, mechanism for nucleophilic substitution in these complexes may be suggested to involve Sn 1 course for tin complexes and SN 2 course for the titanium complex