Neutral and Cationic Bis-Chelate Monoorganosilicon(IV) Complexes of 1-Hydroxy-2-pyridinone

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• 作者：James G. Koch ; William W. BrennesselBradley M. Kraft
• 刊名：Organometallics
• 出版年：2017
• 出版时间：February 13, 2017
• 年：2017
• 卷：36
• 期：3
• 页码：594-604
• 全文大小：648K
• ISSN：1520-6041

文摘

A series of spirocyclic monoorganosilicon compounds of the form RSi(OPO)₂Cl (R = phenyl (1), p-tolyl (2), benzyl (3), Me (4), ^tBu (5), thexyl (6); OPO = 1-oxo-2-pyridinone) was synthesized and characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy, X-ray crystallography, and elemental analysis. In the solid state, complexes 1–3 are neutral and possess cis-OPO ligands in an octahedral arrangement and complexes 4–6 are cationic and possess effectively trans-OPO ligands in nearly ideal square-pyramidal geometries along the Berry pseudorotation coordinate. In 4–6, chloride dissociation is attributed to the additive effect of multiple intermolecular C–H···Cl interactions in their crystals. In DMSO-d₆ solution, compounds 1–6 form cationic hexacoordinate DMSO adducts with trans-OPO ligands, all of which undergo dynamic isomerization with energy barriers of ∼18–19 kcal/mol. Compounds with better leaving groups, (p-tolyl)Si(OPO)₂X (X = I (7), X = triflate (8)), exhibit solution NMR spectra identical with those of 2, supporting anion dissociation in each. The fluoride derivatives RSi(OPO)₂F (R = benzyl (9), Me (10)) exhibit hexacoordinate geometries with cis-OPO ligands in the solid state and exhibit dynamic isomerization in solution. Overall, these studies indicate, in both the solid and solution states, that the trans-OPO ligand arrangement is favored when anions are dissociated and a cis-OPO ligand arrangement when anions are coordinated.