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).

The neutral organosilicon(IV) complex, (C 6 F 5 ) 2 Si(OPO) 2 (OPO = 1-oxopyridin-2-one, C 5 H 4 NO 2 ), was synthesized from (C 6 F 5 ) 2 Si(OCH 3 ) 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, (C 6 F 5 ) 2 Si(OPO) 2 ·0.5THF·0.5C 5 H 12 ( 1 ). p -Tol-yl 2 Si(OPO) 2 ( 2 ) and mesit-yl 2 Si(OPO) 2 ( 3 ) crystallized directly from reaction mixtures of 2 equiv. of Me 3 Si(OPO) with p -tol-yl 2 SiCl 2 and mesit-yl 2 SiCl 2 , 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.