Cryoscopic investigation of the complex formation of organotin compounds

Abstract

1. A method of cryoscopic determination of the equilibrium constants of the stepwise reactions of complex formation in solution was proposed. 2. The interaction of RSnX3, R2SnX2, R3SnX (R=C2H5, C4H9, X=Cl, Br, -OOCCH3) with oxygen- and nitrogen-containing compounds in benzene was investigated. The equilibrium constants of the reactions of complex formation were determined (25 systems). 3. The processes of complex formation of organotin compounds with monodentate ligands proceed in stages with the formation of penta- and hexacoordinated compounds. Bidentate ligands, as a rule, give 1∶1 complexes in one step. 4. Replacement of halogen atoms by alkyl and acyl groups reduces the coordination capacity of organotin compounds. The steric factor has an appreciable influence on the course of the reaction of complex formation. 5. The formation of complexes of dibutyltin diacetate with donor molecules capable of giving hydrogen bonds [CH3OH, (C4H9)2NH] proceeds differently from that with the usual ligands. A hypothesis is advanced on the presence of a supplementary interaction in these systems on account of hydrogen bonds with the carbonyl oxygen of acyl groups. 6. A method of cryoscopic titration was proposed for the analysis of mixtures of organotin halides of various degrees of alkylation.