Coordination of silicon tetrafluoride with pyridine and other nitrogen electron-pair donor molecules

Guertin, Jacques; Onyszchuk, M.

doi:10.1139/v69-212

Cited by 13 publications

(3 citation statements)

References 2 publications

(3 reference statements)

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“…The actual structure of this adduct is depicted in figure 6. This type of neutral adduct is well described in literature (10). The molecular structure of SiF 4 shows a centrosymmetric octahedral geometry at silicon with the pyridine molecules trans to each other and an Si-N distance of 1.93 Å.…”

Section: Resultssupporting

confidence: 68%

Etching of Thermal SiO2 in Supercritical CO2

Malhouitre¹,

Hoeymissen²,

Case³

et al. 2007

ECS Trans.

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Etching of thermal SiO2 using the HF/pyridine complex in supercritical CO2 (scCO2) was studied. Etch rate increases when HF concentration, processing temperature and fluid flow rates are increased. The decrease of the instantaneous etch rate as the processing time increases is attributed to the formation of etching residues on the film surface that act as a diffusion barrier. These residues are soluble in water and are identified as (Pyr)2SiF4 by FTIR analysis. For similar nominal HF concentrations, the SiO2 etch rate in anhydrous pyridine/scCO2 is much higher than in H2O.

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Section: Resultssupporting

confidence: 68%

Etching of Thermal SiO2 in Supercritical CO2

Malhouitre¹,

Hoeymissen²,

Case³

et al. 2007

ECS Trans.

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“…19 F NMR, δ: -57.32 (s). The 1 H and 19 F NMR spectra and the melting point coincided completely with the data for sample 1с synthesized by a de scribed method 12. …”

supporting

confidence: 72%

A new method for dissolution of silica gel in a pentafluoropropionyl fluoride—tertiary amine system

Лермонтов

Малкова

2007

Russ Chem Bull

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A new procedure for the preparation of amino complexes of silicon tetrafluoride was proposed. For this purpose, silica gel is dissolved in a fluoroanhydride-methanol system at room temperature followed by the precipitation of SiF 4 solvate that was formed with tertiary amine (pyridine, 1,10 phenanthroline, 2,2´ bipyridyl). The yields of the formed complexes are 69-83%.Silicon dioxide (SiO 2 , silica) is one of the most abun dant materials on the Earth and the most available source of silicon. The use of silica in chemical synthesis is re stricted to a great extent because of its high chemical stability: SiO 2 is a polymer that can be destroyed only under specific conditions. Depolymerization of SiO 2 (followed by dissolution) in the reactions with alkalis and hydrogen fluoride is well known (Scheme 1, reac tions (1) and (2)). Scheme 1SiO 2 + 2 NaOH Na 2 SiO 3 + H 2 O(1)SiO 2 + 4 HF SiF 4 + 2 H 2 O(2)SiO 2 + 2 C Si + 2 CO(3)SiO 2 + 2 C + 2 Cl 2 SiCl 4 + 2 COThe main reactions of SiO 2 applied in industry are the high temperature reduction (Т > 1200 °С) of silica with carbon to form metallic silicon 1 or (after chlorination) silicon tetrachloride SiCl 4 (see Scheme 1, reactions (3) and (4)). 2 A new procedure of SiO 2 depolymerization, namely, dissolution in alkoxides with distilling off water 3,4 (Scheme 2), has been developed in recent years.This procedure is rather time consuming and results, as a rule, in crystalline solvates containing water and gly col, which suppresses the use of these compounds in or ganometallic synthesis.The purpose of the present work is a search for meth ods of silica (in the form of silica gel) dissolution satisfy ing the following requirements: (a) keep away from too high temperature; (b) afford silicon containing products appropriate for organoelement synthesis or as a source of silicon for electronic industry.We found that silica gel is readily dissolved in an alco holic medium when interacting with easily available fluoroanhydride of pentafluoropropionic acid and after treatment with aromatic amines it forms stable complexes in good yield (Scheme 3). Scheme 3L 2 = 2,2´ bipyridyl (a), 1,10 phenanthroline (b), Py 2 (c)Compounds 1a-c are colorless stable crystalline sub stances soluble in DMSO and DMF; compound 1c is also soluble in water and methanol. The structures of com pounds 1a-c were characterized spectrally and by el emental analysis data. Silica is rapidly dissolved at room temperature when fluoroanhydride is added to afford com pounds 1a-с as precipitates, which do not require further Scheme 2

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“…340 Structurally characterised examples with N-heterocyclic ligands include [SiF 4 (2,2 0 -bipy)], [SiF 4 (1,10-phen)] and trans-[SiF 4 (py) 2 ], all of which are based on distorted octahedral Si(IV) coordination. [341][342][343][344][345][346] Complex anions of the type [SiF 5 L] À (L = NH 3 , NEt 2 H, NMe 3 ), are obtained by reaction of [R 4 N][SiF 5 ] with the amine. They easily lose the amine in vacuum or in solution.…”

Section: Siliconmentioning

confidence: 99%

Medium and high oxidation state metal/non-metal fluoride and oxide–fluoride complexes with neutral donor ligands

2013

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While most high and medium oxidation state (O.S. ≥ 3) metal and non-metal fluorides and oxide fluorides are strong Lewis acids, exploration of their coordination chemistry with neutral ligands has been limited and mostly non-systematic. This is despite the very different properties conferred on the acceptor centre by the small electronegative fluoride ligands compared to the heavier halides. This article sets out these key differences, discusses possible synthetic routes, the key characterisation techniques, and appropriate bonding models. Current knowledge of the coordination chemistry of d, f and p-block fluorides and oxide fluorides with neutral ligands (with donor atoms drawn from Groups 15 and 16 and including N-heterocyclic carbenes) is then presented and discussed, and the differences in properties compared to complexes containing the heavier halides are illustrated. The emphasis is on work published post 1990, but earlier work is also included as essential background and where no more recent information exists. Attention is drawn to unexplored areas meriting investigation and to possible applications of these complexes.

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Coordination of silicon tetrafluoride with pyridine and other nitrogen electron-pair donor molecules

Cited by 13 publications

References 2 publications

Etching of Thermal SiO2 in Supercritical CO2

Etching of Thermal SiO2 in Supercritical CO2

A new method for dissolution of silica gel in a pentafluoropropionyl fluoride—tertiary amine system

Medium and high oxidation state metal/non-metal fluoride and oxide–fluoride complexes with neutral donor ligands

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