Thermochemistry of adducts of some bivalent transition metal bromides with β-picoline N-oxide

The compounds [MBr2(L)2] (where M is Mn(II), Fe(II), Co(II), Ni(II), Cu(II) or Zn(II); L=β-picoline N-oxide (β-picoNO)) 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 β-picoNO in methanol or aqueous 1.2 M HCl 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 (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 metal(II)oxygen bonds (D̄(MO)) have been estimated.