Synthesis and crystal structures of bis-[1-oxopyridin-2-olato(1-)]bis-(penta-fluoro-phen-yl)silicon(IV)-tetra-hydro-furan-pentane (2/1/1), bis-[1-oxopyridin-2-olato(1-)]bis-(p-tol-yl)silicon(IV), and dimesitylbis[1-oxopyridin-2-olato(1-)]silicon(IV)

Abstract

The neutral organosilicon(IV) complex, (C₆F₅)₂Si(OPO)₂ (OPO = 1-oxopyridin-2-one, C₅H₄NO₂), was synthesized from (C₆F₅)₂Si(OCH₃)₂ and 2 equiv. of 1-hy-droxy-pyridin-2-one in tetra-hydro-furan (THF). Single crystals grown from the diffusion of n-pentane into a THF solution were identified as a THF hemisolvate and an n-pentane hemisolvate, (C₆F₅)₂Si(OPO)₂·0.5THF·0.5C₅H₁₂ (1). p-Tol-yl₂Si(OPO)₂ (2) and mesit-yl₂Si(OPO)₂ (3) crystallized directly from reaction mixtures of 2 equiv. of Me₃Si(OPO) with p-tol-yl₂SiCl₂ and mesit-yl₂SiCl₂, respectively, in aceto-nitrile. The oxygen-bonded carbon and nitro-gen atoms of the OPO ligands in 1, 2, and 3 were modeled as disordered indicating co-crystallization of up to three possible diastereomers in each. Solution NMR studies support the presence of exclusively the all-cis isomer in 1 and multiple isomers in 2. Poor solubility of 3 limited its characterization in solution.

Keywords: crystal structure; pyridine N-oxide; pyridinone; silicon.