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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
Author(s) -
Bartlett Philip N.,
Cummings Charles Y.,
Levason William,
Pugh David,
Reid Gillian
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201400179
Subject(s) - chemistry , electrochemistry , germanium , halide , crystallography , ligand (biochemistry) , redox , hydrogen bond , supramolecular chemistry , oxidation state , inorganic chemistry , crystal structure , cyclic voltammetry , molecule , metal , organic chemistry , electrode , biochemistry , receptor , silicon
The Ge IV chlorometallate complexes, [EMIM] 2 [GeCl 6 ], [EDMIM] 2 [GeCl 6 ] and [PYRR] 2 [GeCl 6 ] (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 CH⋅⋅⋅Cl hydrogen bonds, resulting in extended supramolecular assemblies in the solid state. Solution 1 H NMR data also showed cation–anion association. The synthesis and characterisation of Ge II halometallate salts [EMIM][GeX 3 ] (X=Cl, Br, I) and [PYRR][GeCl 3 ], 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 Ge IV species in CH 2 Cl 2 solution showed two distinct, irreversible reduction waves attributed to Ge IV –Ge II and Ge II –Ge 0 , whereas the Ge II species exhibited one irreversible reduction wave. The potential for the Ge II –Ge 0 reduction was unaffected by changing the cation, although altering the oxidation state of the precursor from Ge IV to Ge II does have an effect; for a given cation, reduction from the [GeCl 3 ] − 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 Ge II –Ge 0 couple, such that the reduction potentials for the [GeX 3 ] − salts become significantly less cathodic when the halide (X) is changed Cl→Br→I.