Stereochemistry of the cis-Tetrafluoro Complexes of Titanium with 1-Ac-2-[Ph2P(O)]-Cyclohexane (1RS,2SR) Stereoisomers in СН2Сl2

Abstract

The monodentate phosphoryl-containing ligand 1-Ac-2-[Ph₂P(O)]-cyclohexane (L) bearing two asymmetric carbon atoms is synthesized. The study of its crystal structure shows that L is a racemic mixture of (1R,2S) and (1S,2R) stereoisomers. The complex formation of L with TiF₄ in СН₂Сl₂ is studied by ¹⁹F{¹Н} and ³¹Р{¹Н} NMR spectroscopy. The compositions of the complexes formed in the solution are determined. Racemic and meso-diastereomers of the octahedral complex cis-TiF₄L₂ are formed in the solution as found by an analysis of the ¹⁹F and ³¹Р NMR spectra taking into account the concept of heterotropy of organic compounds. The influence of the optical configuration of stereoisomers of the monodentate ligand coexisting in the coordination sphere of the [MF₄L₂] octahedral tetrafluoro complexes of transition d⁰ metals on the chemical shifts of the fluorine atoms arranged in the trans positions relative to each other is shown. In the meso-diastereomer of cis-TiF₄L₂, this results in a nonequivalence of the fluorine atoms on the F–Ti–F' ordinate of the octahedron, and the spin-spin coupling constant J_FF' = 286.1 Hz is observed in the ¹⁹F{¹H} NMR spectrum.