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Halometallate complexes of germanium(II) and (IV): probing the role of cation, oxidation state and halide on the structural and electrochemical properties

Halometallate complexes of germanium(II) and (IV): probing the role of cation, oxidation state and halide on the structural and electrochemical properties
Halometallate complexes of germanium(II) and (IV): probing the role of cation, oxidation state and halide on the structural and electrochemical properties
The GeIV chlorometallate complexes, [EMIM]2[GeCl6], [EDMIM]2[GeCl6] and [PYRR]2[GeCl6] (EMIM=1-ethyl-3-methylimidazolium; EDMIM=2,3-dimethyl-1-ethylimidazolium; PYRR=N-butyl-N-methylpyrrolidinium) have been synthesised and fully characterised; the first two also by single-crystal X-ray diffraction. The imidazolium chlorometallates exhibited significant C[BOND]H???Cl hydrogen bonds, resulting in extended supramolecular assemblies in the solid state. Solution 1H?NMR data also showed cation–anion association. The synthesis and characterisation of GeII halometallate salts [EMIM][GeX3] (X=Cl, Br, I) and [PYRR][GeCl3], including single-crystal X-ray analyses for the homologous series of imidazolium salts, are reported. In these complexes, the intermolecular interactions are much weaker in the solid state and they appear not to be significantly associated in solution. Cyclic-voltammetry experiments on the GeIV species in CH2Cl2 solution showed two distinct, irreversible reduction waves attributed to GeIV–GeII and GeII–Ge0, whereas the GeII species exhibited one irreversible reduction wave. The potential for the GeII–Ge0 reduction was unaffected by changing the cation, although altering the oxidation state of the precursor from GeIV to GeII does have an effect; for a given cation, reduction from the [GeCl3]? salts occurred at a less cathodic potential. The nature of the halide co-ligand also has a marked influence on the reduction potential for the GeII–Ge0 couple, such that the reduction potentials for the [GeX3]? salts become significantly less cathodic when the halide (X) is changed Cl?Br?I.
cyclic voltammetry, germanium, halides, hydrogen bonds, x-ray diffraction
0947-6539
5019-5027
Bartlett, Philip
d99446db-a59d-4f89-96eb-f64b5d8bb075
Cummings, Charles
37ed515b-eb09-4c6b-9c66-61013c8c132a
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Pugh, David
9ec61267-ae4d-40d8-bebf-0d603e2588d3
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Bartlett, Philip
d99446db-a59d-4f89-96eb-f64b5d8bb075
Cummings, Charles
37ed515b-eb09-4c6b-9c66-61013c8c132a
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Pugh, David
9ec61267-ae4d-40d8-bebf-0d603e2588d3
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037

Bartlett, Philip, Cummings, Charles, Levason, William, Pugh, David and Reid, Gillian (2014) Halometallate complexes of germanium(II) and (IV): probing the role of cation, oxidation state and halide on the structural and electrochemical properties. Chemistry - A European Journal, 20 (17), 5019-5027. (doi:10.1002/chem.201400179). (PMID:24644266)

Record type: Article

Abstract

The GeIV chlorometallate complexes, [EMIM]2[GeCl6], [EDMIM]2[GeCl6] and [PYRR]2[GeCl6] (EMIM=1-ethyl-3-methylimidazolium; EDMIM=2,3-dimethyl-1-ethylimidazolium; PYRR=N-butyl-N-methylpyrrolidinium) have been synthesised and fully characterised; the first two also by single-crystal X-ray diffraction. The imidazolium chlorometallates exhibited significant C[BOND]H???Cl hydrogen bonds, resulting in extended supramolecular assemblies in the solid state. Solution 1H?NMR data also showed cation–anion association. The synthesis and characterisation of GeII halometallate salts [EMIM][GeX3] (X=Cl, Br, I) and [PYRR][GeCl3], including single-crystal X-ray analyses for the homologous series of imidazolium salts, are reported. In these complexes, the intermolecular interactions are much weaker in the solid state and they appear not to be significantly associated in solution. Cyclic-voltammetry experiments on the GeIV species in CH2Cl2 solution showed two distinct, irreversible reduction waves attributed to GeIV–GeII and GeII–Ge0, whereas the GeII species exhibited one irreversible reduction wave. The potential for the GeII–Ge0 reduction was unaffected by changing the cation, although altering the oxidation state of the precursor from GeIV to GeII does have an effect; for a given cation, reduction from the [GeCl3]? salts occurred at a less cathodic potential. The nature of the halide co-ligand also has a marked influence on the reduction potential for the GeII–Ge0 couple, such that the reduction potentials for the [GeX3]? salts become significantly less cathodic when the halide (X) is changed Cl?Br?I.

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e-pub ahead of print date: 18 March 2014
Published date: 22 April 2014
Keywords: cyclic voltammetry, germanium, halides, hydrogen bonds, x-ray diffraction
Organisations: Chemistry

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Local EPrints ID: 368635
URI: http://eprints.soton.ac.uk/id/eprint/368635
ISSN: 0947-6539
PURE UUID: 1b6e6b45-f49e-4077-9ee0-90ffd3384c50
ORCID for Philip Bartlett: ORCID iD orcid.org/0000-0002-7300-6900
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: 06 Sep 2014 12:19
Last modified: 18 Feb 2021 16:34

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Author: Philip Bartlett ORCID iD
Author: Charles Cummings
Author: William Levason ORCID iD
Author: David Pugh
Author: Gillian Reid ORCID iD

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