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), tetram ethylthiourea (tmtu) or 1-allyl-2-thiorea (atu)) were synthesized and chara cterized by melting points, elemental analysis, thermal studies and IR spec troscopy. The enthalpies of dissolution of the adducts, tin(IV) chloride an d 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 (Delta(r)H(0)), t he standard enthalpies of formation (Delta(f)H(0)), the standard enthalpies of decomposition (Delta(D)H(0)) the lattice standard enthalpies (Delta(M)H (0)) and the standard enthalpies of the Lewis acid/base reactions in the ga seous phase (Delta(r)H(0)(g)). The mean standard enthalpies of the tin-oxyg en ((D) over bar(Sn-O)) and tin-sulphur ((D) over bar(Sn-S)) bonds have bee n estimated. (C) 2000 Elsevier Science B.V. All rights reserved.