Synthesis of Titanium and Zirconium Complexes with 2‐­Pyridonate and 2, 6‐Pyridinedithiolate Ligands

Abstract

AbstractTreatment of complex [Cp2TiCl2] with the lithium salt of 2‐hydroxypyridine afforded complex [Cp2Ti(Opy)2] (1), whereas the same synthetic strategy applied to the analogous zirconium compound [Cp2ZrCl2] did not worked. However, the use of the metallocene [Cptt2ZrMe2] with protic ligands allowed directing the reactivity towards protonation of the methyl groups attached to zirconium. To check this approach we reacted [Cptt2ZrMe2] with methanol affording complex [Cptt2ZrMe(OMe)] (2), which was characterized in situ by NMR techniques. In the same line, the reaction of [Cptt2ZrMe2] with 2‐hydroxypyridine gave complex [Cptt2Zr(Me)(Opy)] (3); forcing the conditions of this reaction did not lead to the expected complex [Cptt2Zr(Opy)2], most probably due to the steric hindrance exerted by the bulky cyclopentadienyl ligands. Further reactions of complex 3 with ligands having acidic protons also led to the recovery of the starting complex. However, when shifting to the bifunctional ligand 2, 6‐dimercaptopyridine [py(SH)2] a double protonation of the methyl ligands in [Cptt2ZrMe2] occurred, allowing the isolation of mononuclear complex [Cptt2Zr(κS,κS,κN‐pyS2)] (4), upon evolution of methane. The molecular structure of complex 4 was determined by X‐ray methods, showing the zirconium atom in a highly distorted trigonal bipyramidal arrangement; structural parameters indicate a conventional Zr–N bond, but rather weak Zr–S interactions.