Specifics of titanium tetrafluoride complexation with Ph2P(O)(CH2)2C(O)NMe2: The remarkable stability of the seven-membered chelate heterocycle TiOPCCCO and its conformational isomerism in solution

The composition and structure of the products of the reaction of titanium tetrafluoride with Ph₂P(O)(CH₂)₂C(O)NМе₂ (L), the simplest representative of diphenyl[2-(N,N-dialkylcarbamoyl)ethyl]phosphine oxides, in a СН₂Сl₂ have been studied by ¹⁹F and ³¹P NMR. It has been shown for the first time that functionalized phosphine oxides form stable seven-membered chelate heterocycles on complexes of d° transition metals. On the basis of NMR data, previously unknown conformational isomerism of the seven-membered TiOPCCCO heterocycle in solution has been proposed. A simple and rather efficient method of synthesis of the ligand (L) from commercially available reagents has been developed.