Fluoro-Germanium (IV) Cations with Neutral Co-Ligands—Synthesis, Properties and Comparison with Neutral GeF4 Adducts
Fluoro-Germanium (IV) Cations with Neutral Co-Ligands—Synthesis, Properties and Comparison with Neutral GeF4 Adducts
The reaction of [GeF4L2], L = dmso (Me2SO), dmf (Me2NCHO), py (pyridine), pyNO (pyridine-N-oxide), OPPh3, OPMe3, with Me3SiO3SCF3 (TMSOTf) and monodentate ligands, L, in a 1:1:1 molar ratio in anhydrous CH2Cl2 formed the monocations [GeF3L3][OTf]. These rare trifluoro-germanium (IV) cations were characterised by microanalysis, IR, 1H, 19F{1H} and, where appropriate, 31P{1H} NMR spectroscopy. The 19F{1H} NMR data show that in CH3NO2 solution the complexes exist as a mixture of mer and fac isomers, with the mer isomer invariably having the higher abundance. The X-ray structure of mer-[GeF3(OPPh3)3][OTf] is also reported. The attempts to remove a second fluoride using a further equivalent of TMSOTf and L were mostly unsuccessful, although a mixture of [GeF2(OAsPh3)4][OTf]2 and [GeF3(OAsPh3)3][OTf] was obtained using excess TMSOTf and OAsPh3. The reaction of [GeF4(MeCN)2] with TMSOTf in CH2Cl2 solution, followed by the addition of 2,2′:6′,2”-terpyridine (terpy) formed mer-[GeF3(terpy)][OTf], whilst a similar reaction with 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-tacn) in MeCN solution produced fac-[GeF3(Me3-tacn)][OTf]. Dicationic complexes bearing the GeF22+ fragment were isolated using the tetra-aza macrocycles, 1,4,7,10-tetramethyl-1,4,7,10-tetra-azacyclododecane (Me4-cyclen) and 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetradecane (Me4-cyclam), which reacted with [GeF4(MeCN)2] and two equivalents of TMSOTf to cleanly form the dicationic difluoride salts, cis-[GeF2(Me4-cyclen)][OTf]2 and trans-[GeF2(Me4-cyclam)][OTf]2. The 19F{1H} NMR spectroscopy shows that in CH3NO2 solution there are four stereoisomers present for trans-[GeF2(Me4-cyclam)][OTf]2, whereas the smaller ring-size of Me4-cyclen accounts for the formation of only cis-[GeF2(Me4-cyclen)][OTf], and is confirmed crystallographically. New spectroscopic data are also reported for [GeF4(L)2] (L = dmso, dmf and pyNO). Density functional theory calculations were used to probe the effect on the bonding as fluoride ligands were sequentially removed from the germanium centre in the OPMe3 complexes.
cations, crystal structures, fluoride, germanium
Woodward, Madeleine S.
904ae45d-221e-4ce3-ab2a-325451139bec
King, Rhys P.
2f9548b8-fc3b-447c-a5df-de5a3e513a39
Bannister, Robert D.
4dd3eb2a-5ba7-46de-9277-8dd7e8e39b74
Grigg, Julian
fb292b6d-105f-468c-b056-d8fae1dc79b5
McRobbie, Graeme
b12f273f-dd78-4ff8-a423-b0b5158091c7
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
27 July 2022
Woodward, Madeleine S.
904ae45d-221e-4ce3-ab2a-325451139bec
King, Rhys P.
2f9548b8-fc3b-447c-a5df-de5a3e513a39
Bannister, Robert D.
4dd3eb2a-5ba7-46de-9277-8dd7e8e39b74
Grigg, Julian
fb292b6d-105f-468c-b056-d8fae1dc79b5
McRobbie, Graeme
b12f273f-dd78-4ff8-a423-b0b5158091c7
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Woodward, Madeleine S., King, Rhys P., Bannister, Robert D., Grigg, Julian, McRobbie, Graeme, Levason, William and Reid, Gillian
(2022)
Fluoro-Germanium (IV) Cations with Neutral Co-Ligands—Synthesis, Properties and Comparison with Neutral GeF4 Adducts.
Inorganics, 10 (8), [107].
(doi:10.3390/inorganics10080107).
Abstract
The reaction of [GeF4L2], L = dmso (Me2SO), dmf (Me2NCHO), py (pyridine), pyNO (pyridine-N-oxide), OPPh3, OPMe3, with Me3SiO3SCF3 (TMSOTf) and monodentate ligands, L, in a 1:1:1 molar ratio in anhydrous CH2Cl2 formed the monocations [GeF3L3][OTf]. These rare trifluoro-germanium (IV) cations were characterised by microanalysis, IR, 1H, 19F{1H} and, where appropriate, 31P{1H} NMR spectroscopy. The 19F{1H} NMR data show that in CH3NO2 solution the complexes exist as a mixture of mer and fac isomers, with the mer isomer invariably having the higher abundance. The X-ray structure of mer-[GeF3(OPPh3)3][OTf] is also reported. The attempts to remove a second fluoride using a further equivalent of TMSOTf and L were mostly unsuccessful, although a mixture of [GeF2(OAsPh3)4][OTf]2 and [GeF3(OAsPh3)3][OTf] was obtained using excess TMSOTf and OAsPh3. The reaction of [GeF4(MeCN)2] with TMSOTf in CH2Cl2 solution, followed by the addition of 2,2′:6′,2”-terpyridine (terpy) formed mer-[GeF3(terpy)][OTf], whilst a similar reaction with 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-tacn) in MeCN solution produced fac-[GeF3(Me3-tacn)][OTf]. Dicationic complexes bearing the GeF22+ fragment were isolated using the tetra-aza macrocycles, 1,4,7,10-tetramethyl-1,4,7,10-tetra-azacyclododecane (Me4-cyclen) and 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetradecane (Me4-cyclam), which reacted with [GeF4(MeCN)2] and two equivalents of TMSOTf to cleanly form the dicationic difluoride salts, cis-[GeF2(Me4-cyclen)][OTf]2 and trans-[GeF2(Me4-cyclam)][OTf]2. The 19F{1H} NMR spectroscopy shows that in CH3NO2 solution there are four stereoisomers present for trans-[GeF2(Me4-cyclam)][OTf]2, whereas the smaller ring-size of Me4-cyclen accounts for the formation of only cis-[GeF2(Me4-cyclen)][OTf], and is confirmed crystallographically. New spectroscopic data are also reported for [GeF4(L)2] (L = dmso, dmf and pyNO). Density functional theory calculations were used to probe the effect on the bonding as fluoride ligands were sequentially removed from the germanium centre in the OPMe3 complexes.
Text
inorganics-10-00107 (2)
- Version of Record
More information
Accepted/In Press date: 13 July 2022
Published date: 27 July 2022
Additional Information:
Funding Information:
This research was funded by a CASE studentship to M.S.W from GE Healthcare and EPSRC grant number EP/R513325/1, and by EPSRC through grant numbers EP/N035437/1, EP/N509747/1 and through the EPSRC Mithras Programme Grant (EP/S032789/1).
Publisher Copyright:
© 2022 by the authors.
Keywords:
cations, crystal structures, fluoride, germanium
Identifiers
Local EPrints ID: 471432
URI: http://eprints.soton.ac.uk/id/eprint/471432
ISSN: 2304-6740
PURE UUID: 97484387-a08a-458f-b24a-698ca61f03b7
Catalogue record
Date deposited: 08 Nov 2022 18:03
Last modified: 18 Mar 2024 02:39
Export record
Altmetrics
Contributors
Author:
Madeleine S. Woodward
Author:
Rhys P. King
Author:
Robert D. Bannister
Author:
Julian Grigg
Author:
Graeme McRobbie
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
