The acceptor properties of silicon(<scp>IV</scp>). ‘Class (b)’ or ‘soft acid’ behaviour by silicon tetrachloride and silicon tetrabromide

Beattie, I. R.; Ozin, G. A.

doi:10.1039/j19690002267

Cited by 22 publications

(7 citation statements)

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“…352 The only reports of soft donor ligand complexes with silicon fluorides are SiF 4 ÁnPMe 3 (n = 1 or 2), formed at very low temperatures in the absence of solvent and identified by tensimetric measurements and Raman spectroscopy. 353,354 Recent studies in our own laboratory failed to isolate any adducts from the reaction of SiF 4 with strongly s-donating alkylphosphines, including Et 2 P(CH 2 ) 2 PEt 2 , PMe 3 and o-C 6 H 4 (PMe 2 ) 2 , or with the dithioethers, RS(CH 2 ) 2 SR (R = Me, Et) in either CH 2 Cl 2 or toluene solutions with rigorous exclusion of O 2 and moisture. Similarly, VT NMR spectroscopic studies (295-190 K) on mixtures of SiF 4 and the phosphines did not provide evidence of complex formation, suggesting that any interaction is very weak even at the lowest temperatures.…”

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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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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“…Old reports [260] of [SiF 4 (PMe 3 ) n ] (n = 1 or 2) formed at low temperatures in the absence of solvent, and identified by their Raman spectra, are not necessarily contradicted by the NMR results, since the experimental conditions are different, and these would merit reinvestigation. Very recently the trans-[SiX 4 (PMe 3 ) 2 ] (X = Cl or Br) have been re-examined [261].…”

Section: Siliconmentioning

confidence: 99%

Coordination chemistry of the main group elements with phosphine, arsine and stibine ligands

Burt

Levason

Reid

2014

Coordination Chemistry Reviews

104

137

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“…21 The only report of soft donor ligand complexes with SiF 4 is SiF 4 •nPMe 3 (n = 1 or 2) formed at very low temperatures in the absence of solvent and identified by tensimetric measurements and Raman spectroscopy. 22 The aim of the present study was to investigate the formation of the SiF 4 adducts with Odonor ligands, to establish if soft donor ligands (P, As or S) form adducts, and to draw comparisons with results from our recent work on SnF 4 and GeF 4 adducts; there are notable differences compared with SiCl 4 adducts which will also be discussed.…”

Section: Introductionmentioning

confidence: 99%

Hypervalent neutral O-donor ligand complexes of silicon tetrafluoride, comparisons with other group 14 tetrafluorides and a search for soft donor ligand complexes

et al. 2011

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The hypervalent adducts of SiF(4), trans-[SiF(4)(R(3)PO)(2)] (R = Me, Et or Ph), cis-[SiF(4){R(2)P(O)CH(2)P(O)R(2)}] (R = Me or Ph), cis-[SiF(4)(pyNO)(2)] and trans-[SiF(4)(DMSO)(2)] have been prepared from SiF(4) and the ligands in anhydrous CH(2)Cl(2), and characterised by microanalysis, IR and VT multinuclear ((1)H, (19)F, (31)P) NMR spectroscopy. The NMR studies show extensive dissociation at ambient temperatures in non-coordinating solvents, but mixtures of cis and trans isomers of the monodentate ligand complexes were identified at low temperatures. Crystal structures are reported for trans-[SiF(4)(R(3)PO)(2)] (R = Me or Ph), and cis-[SiF(4)(pyNO)(2)]. The GeF(4) analogues cis-[GeF(4){R(2)P(O)(CH(2))(n)P(O)R(2)}] (R = Me or Ph, n = 1; R = Ph, n = 2) were similarly characterised and the structures of cis-[GeF(4){R(2)P(O)CH(2)P(O)R(2)}] (R = Me or Ph) determined. The reaction of R(3)AsO (R = Me or Ph) with SiF(4) does not give simple adducts, but forms [R(3)AsOH](+) cations as fluorosilicate salts. SiF(4) adducts of some ether ligands (including THF, 12-crown-4) were also characterised by (19)F NMR spectroscopy in solution at low temperatures (∼190 K), but are fully dissociated at room temperature. Attempts to isolate, or even to identify, SiF(4) adducts with phosphine or thioether ligands in solution at 190 K were unsuccessful, contrasting with the recent isolation and detailed characterisation of GeF(4) analogues. The chemistry of SiF(4) with these oxygen donor ligands, and with soft donors (P, As, S or Se), is compared and contrasted with those of GeF(4), SnF(4) and SiCl(4). The key energy factors determining stability of these complexes are discussed.

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The acceptor properties of silicon(IV). ‘Class (b)’ or ‘soft acid’ behaviour by silicon tetrachloride and silicon tetrabromide

Cited by 22 publications

References 0 publications

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

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

Coordination chemistry of the main group elements with phosphine, arsine and stibine ligands

Hypervalent neutral O-donor ligand complexes of silicon tetrafluoride, comparisons with other group 14 tetrafluorides and a search for soft donor ligand complexes

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