Thermochemistry of adducts of tin(IV) bromide with heterocyclic bases

The compounds [SnBr4(L)n] (where L is pyridine (py), 3-methylpyridine (β-pico), 4-methylpyridine (γ-pico), piperidine (pipd), morpholine (morph), piperazine (pipz), 3-cyanopyridine (3-cyanopy), 4-cyanopyridine (4-cyanopy), quinoline (quin) or 2,2′-bipyridine (bipy) and n=1 or 2) were synthesized and characterized by elemental analysis, melting points, thermal studies and IR spectroscopy. The enthalpies of dissolution of adducts, tin(IV) bromide and ligands in 25% (v/v) aqueous 1.2 M HCl in methanol were measured and, by thermochemical cycles, the standard enthalpies for the Lewis acid/base reaction (ΔrHθ), the standard enthalpies of formation (ΔfHθ), the standard enthalpies of decomposition (ΔDHθ), the lattice standard enthalpies (ΔMHθ) and the standard enthalpies for the Lewis acid/base reaction in the gaseous phase (ΔrHθ(g)) are determined. The mean standard enthalpies of the tin-nitrogen coordinated bonds D̄(SnN) are estimated.