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

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

The hypervalent adducts of SiF4, trans-[SiF4(R3PO)2] (R = Me, Et or Ph), cis-[SiF4{R2P(O)CH2P(O)R2}] (R = Me or Ph), cis-[SiF4(pyNO)2] and trans-[SiF4(DMSO)2] have been prepared from SiF4 and the ligands in anhydrous CH2Cl2, and characterised by microanalysis, IR and VT multinuclear (1H, 19F, 31P) 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-[SiF4(R3PO)2] (R = Me or Ph), and cis-[SiF4(pyNO)2]. The GeF4 analogues cis-[GeF4{R2P(O)(CH2)nP(O)R2}] (R = Me or Ph, n = 1; R = Ph, n = 2) were similarly characterised and the structures of cis-[GeF4{R2P(O)CH2P(O)R2}] (R = Me or Ph) determined. The reaction of R3AsO (R = Me or Ph) with SiF4 does not give simple adducts, but forms [R3AsOH]+ cations as fluorosilicate salts. SiF4 adducts of some ether ligands (including THF, 12-crown-4) were also characterised by 19F NMR spectroscopy in solution at low temperatures (190 K), but are fully dissociated at room temperature. Attempts to isolate, or even to identify, SiF4 adducts with phosphine or thioether ligands in solution at 190 K were unsuccessful, contrasting with the recent isolation and detailed characterisation of GeF4 analogues. The chemistry of SiF4 with these oxygen donor ligands, and with soft donors (P, As, S or Se), is compared and contrasted with those of GeF4, SnF4 and SiCl4. The key energy factors determining stability of these complexes are discussed.
0300-9246
1584-1593
George, Kathryn
1e9bf4f9-226e-446e-9ef3-dd61c7f7aa11
Hector, Andrew L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
Levason, William
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Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Sanderson, George
28c458aa-326b-4029-b8cc-cc3035d4acd2
Webster, Michael
f26c6e36-cb2e-486e-b2ed-b0d25a3a71f7
Zhang, Wenjian
1f80ac5e-d4c2-4720-b19e-be700cd411e7
George, Kathryn
1e9bf4f9-226e-446e-9ef3-dd61c7f7aa11
Hector, Andrew L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Sanderson, George
28c458aa-326b-4029-b8cc-cc3035d4acd2
Webster, Michael
f26c6e36-cb2e-486e-b2ed-b0d25a3a71f7
Zhang, Wenjian
1f80ac5e-d4c2-4720-b19e-be700cd411e7

George, Kathryn, Hector, Andrew L., Levason, William, Reid, Gillian, Sanderson, George, Webster, Michael and Zhang, Wenjian (2011) Hypervalent neutral O-donor ligand complexes of silicon tetrafluoride, comparisons with other group 14 tetrafluorides and a search for soft donor ligand complexes. Dalton Transactions, 40 (7), 1584-1593. (doi:10.1039/c0dt01115k). (PMID:21240413)

Record type: Article

Abstract


The hypervalent adducts of SiF4, trans-[SiF4(R3PO)2] (R = Me, Et or Ph), cis-[SiF4{R2P(O)CH2P(O)R2}] (R = Me or Ph), cis-[SiF4(pyNO)2] and trans-[SiF4(DMSO)2] have been prepared from SiF4 and the ligands in anhydrous CH2Cl2, and characterised by microanalysis, IR and VT multinuclear (1H, 19F, 31P) 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-[SiF4(R3PO)2] (R = Me or Ph), and cis-[SiF4(pyNO)2]. The GeF4 analogues cis-[GeF4{R2P(O)(CH2)nP(O)R2}] (R = Me or Ph, n = 1; R = Ph, n = 2) were similarly characterised and the structures of cis-[GeF4{R2P(O)CH2P(O)R2}] (R = Me or Ph) determined. The reaction of R3AsO (R = Me or Ph) with SiF4 does not give simple adducts, but forms [R3AsOH]+ cations as fluorosilicate salts. SiF4 adducts of some ether ligands (including THF, 12-crown-4) were also characterised by 19F NMR spectroscopy in solution at low temperatures (190 K), but are fully dissociated at room temperature. Attempts to isolate, or even to identify, SiF4 adducts with phosphine or thioether ligands in solution at 190 K were unsuccessful, contrasting with the recent isolation and detailed characterisation of GeF4 analogues. The chemistry of SiF4 with these oxygen donor ligands, and with soft donors (P, As, S or Se), is compared and contrasted with those of GeF4, SnF4 and SiCl4. The key energy factors determining stability of these complexes are discussed.

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Published date: 2011

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Local EPrints ID: 177655
URI: http://eprints.soton.ac.uk/id/eprint/177655
ISSN: 0300-9246
PURE UUID: 025f7c7f-6177-4266-9238-73a6fcd4f5f2
ORCID for Andrew L. Hector: ORCID iD orcid.org/0000-0002-9964-2163
ORCID for William Levason: ORCID iD orcid.org/0000-0003-3540-0971
ORCID for Gillian Reid: ORCID iD orcid.org/0000-0001-5349-3468

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Date deposited: 18 Mar 2011 11:28
Last modified: 20 Jul 2019 01:28

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Contributors

Author: Kathryn George
Author: William Levason ORCID iD
Author: Gillian Reid ORCID iD
Author: George Sanderson
Author: Michael Webster
Author: Wenjian Zhang

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