Transition-metal Schiff-base complexes as ligands in tin chemistry. Part 3. An X-ray crystallographic and tin-119 Mössbauer spectroscopic study of adduct formation between tin(IV) Lewis acids and nickel 3-methoxysalicylaldimine complexes

Abstract

1:1 Addition complexes of [Ni^IIL]·H₂O [H₂L =N,N′-bis(3-methoxysalicylidene)ethylenediamine (3MeO-H₂salen), N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine (3MeO-H₂salpn) or N,N′-bis(3-methoxysalicylidene)-o-phenylenediamine (3O-H₂salphen)] with SnR₂Cl₂(R = Me or Ph), SnBuⁿCl₃, or SnCl₄ have been found to be generally monoaqua adducts of the tin Lewis acids with the water engaged in hydrogen bonding with the methoxy and phenolic oxygen atoms of the Schiffbase ligand. Both water and methoxy oxygen atoms are involved in donor-bond formation to tin in the polymeric structures 2SnMe₂Cl₂·[Ni(3MeO-salen)]·H₂O and SnMe₂Cl₂·[Ni(3MeO-salphen)]·H₂O, each of which has two very different tin environments. The two octahedral tin sites in the structure of SnMe₂Cl₂·2[Ni(3MeO-salphen)·H₂O] appear to result from two isomeric forms of the adduct co-existing in a lattice as a result of hydrogen-bonding interactions. Crystal-structure determinations revealed that the monoaqua adducts of dimethyltin dichloride which exist in the structures SnMe₂Cl₂·[Ni(3MeO-salen)]·H₂O and SnMe₂Cl₂·[Ni(3MeO-salon)]·H₂O differ in that, in the former tin is in a trigonal-bipyramidal environment, whereas in the latter it is in an octahedral environment as a result of an intermolecular Sn ⋯ Cl contact of 3.615 Å.