Thermochemistry of adducts of tin(IV) bromide with amide and thioamide ligands

The compounds SnBr4·nL (where L is urea (u), 1,1-dimethylurea (1,1-dmu), 1,3-dimethylurea (1,3-dmu), tetramethylurea (tmu), thiourea (tu), tetramethylthiourea (tmu) or 1-allyl-2-thiourea (atu) and n=2, 3 or 4) were synthesized and characterized by melting points, elemental analysis, thermal analysis and IR spectroscopy. The enthalpies of dissolution of the adducts, tin(IV) bromide and ligands in methanol were measured and by using thermochemical cycles the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reaction (ΔrH0); the standard enthalpies of formation (ΔfH0); the standard enthalpies of decomposition (ΔDH0); the lattice standard enthalpies (ΔMH0) and the standard enthalpies of the Lewis acid/base reaction in the gaseous phase (ΔrH0(g)). The mean standard enthalpies of the tinoxygen (D̄(SnO)) and tinsulphur (D̄(SnS)) bonds have been estimated.