Synthesis, characterization and DFT studies of novel –CH2– capped and non-capped salan complexes

Abstract

The tetradentate diaminobis(phenolato) “salan” ligand precursors, N,N′-bis-(2-hydroxy-3-iPr-5-Cl-6-Me-benzyl)-4-methylimidazolidine (H2L1) is synthesized. Reaction of H2L1 with MoO2(acac)2, FeCl3, VOSO4 and Ni(OAc)2, resulted in the formation of [MoO2(L1A)] (1), [(Fe(L1A))2(µ-Cl)(µ-OCH3)], (2), [(VO(L1A))2(µ-O)]·THF (3) and [Ni(L1A)] (4), wherein (L1A)2− resulted from the loss of the capping –CH2- moiety of H2L1 upon complex formation. However the capping –CH2- moiety between the two N-amine atoms is retained in the reaction of H2L1 with Ti(OiPr)4, resulting in formation of the dinuclear complex [(Ti(L1)(OiPr))2(µ-O)] (5). All compounds obtained are characterized by various physicochemical techniques (elemental analysis, IR, UV–Vis and NMR spectroscopy, and ESI-MS), and by single crystal X-ray diffraction analysis in the case of complexes 1–3. The several factors relevant for the formation of the compounds, as well as cleavage or non-cleavage of the –CH2- bridge in the salan ligands, are elucidated with the help of DFT calculations.