Thermochemistry of adducts of tin(IV) chloride with amides and thioamides

The compounds [SnCl4(L)2] (where L is urea (u), 1,1-dimethylurea (1,1-dmu), 1,3-dimethylurea (1,3-dmu), tetramethylurea (tmu), thiourea (tu), tetramethylthiourea (tmtu) or 1-allyl-2-thiourea (atu)) were synthesized and characterized by melting points, elemental analysis, thermal studies and IR spectroscopy. The enthalpies of dissolution of the adducts, tin(IV) chloride 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 reactions (ΔrHθ), the standard enthalpies of formation (ΔfHθ), the standard enthalpies of decomposition (ΔDHθ), the lattice standard enthalpies (ΔMHθ) and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase (ΔrHθ(g)). The mean standard enthalpies of the tin-oxygen (D̄(Sn–O)) and tin-sulphur (D̄(Sn–S)) bonds have been estimated.