Thermochemistry of adducts of some bivalent transition metal bromides with quinoline

The compounds [MBr2(quin)n] (where M is Mn(II), Co(II), Ni(II), Cu(II) or Zn(II); quin, quinoline; n = 1 or 2) were synthesized and characterized by melting points, elemental analysis, thermal analysis and electronic and IR spectroscopy. The enthalpies of dissolution of the adducts, metal(II) bromides and quinoline in methanol or 1.2 M aqueous HCl were measured and by using thermochemical cycles, the following parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reactions (ΔrH°), the standard enthalpies of formation (ΔfH°), the standard enthalpies of decomposition (ΔDH°), the lattice standard enthalpies (ΔMH°) and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase (ΔrH  °(g)). The mean bond dissociation enthalpies of the M(II)–nitrogen bonds (D¯(M–N)) have been estimated as well as the enthalpies of adduct formation in the gaseous phase.