Titanium(IV) complexes of oximes – Novel binding modes

In this paper we investigate the coordination of various oximes (CN–OH) with titanium(IV). We have chosen three ligands (1H2–3H2) with a phenolic moiety and one ligand 4H with a pyridine group. It was shown that ligands 1H2 to 3H2 react with Ti(OiPr)4 to form complexes with a generic formula Ti3(L)2(OiPr)8, where each oxime bridges between the three titanium centres. Interestingly, these complexes are clusters made up of three titanium atoms, with one titanium centre sitting above the other two. This titanium centre can be thought of as a trapped Ti(OiPr)4 molecule, 1H and 13C NMR spectroscopy indicates that the solid-state structures are maintained in solution. Subtle differences between the three X-ray structures are discussed. Ligand 4H readily reacts with Ti(OiPr)4 forming a dimeric species, Ti2(4)4(OiPr)4, where the titanium centres are linked by bridging isopropoxide moieties.

Graphical abstractThe crystal and solution structures of four Ti(IV) oxime complexes are reported. The complexes show, for the first time, a triply bridging mode of the oxime ligands with Ti(IV) characterised via X-ray crystallography. 1H and 13C NMR spectroscopic studies show that the solid-state structures are maintained in solution.Figure optionsDownload full-size imageDownload as PowerPoint slide