In:
European Journal of Inorganic Chemistry, Wiley, Vol. 2020, No. 17 ( 2020-05-10), p. 1562-1573
Abstract:
Five mononuclear tris‐chelate complexes of Fe II , Co II , Ni II and Zn II , containing the bidentate ligand 3‐methyl‐1‐(2‐pyridyl)imidazolyl‐2‐thione ( L ), have been synthesised and characterised, namely [ M II ( L ) 3 ](BF 4 ) 2 , where M = Fe ( 1 ), Co ( 2 ), Ni ( 3 ) and Zn ( 4 ), and [Fe II ( L ) 3 ](PF 6 ) 2 { 1‐(PF 6 ) 2 }. The complexes have been characterised by standard methods and single‐crystal X‐ray diffraction, showing that all the complexes are isostructural and isomorphs, crystallising in the P 1 space group, except for 1‐(PF 6 ) 2 , which crystallises in the P 2 1 / c , as expected due to the different size and symmetry of the anion. The metal centre is found in a distorted meridional‐N 3 S 3 octahedral geometry. In all the complexes, two ligand strands within the same complex cation unit interact via an almost perfect face‐to‐face π–π stacking. The double intramolecular interaction occurs between a pyridyl ring of one ligand strand and an imidazolyl ring of a second ligand strand and vice versa. The Fe II and Co II complexes, 1 and 2 , are stabilised in the high spin state, based on the bond lengths and angles obtained by SC‐XRD and by VT‐magnetic studies in the solid state and NMR Evans method in CD 3 CN solution. The cyclic voltammetry behaviour for compounds 1 – 4 showed an EC mechanism for the oxidation process, in which two ligand strands are electrochemically oxidised, instead of the metal centre, followed by a chemical process (de‐coordination and dimerisation). Whereas, the reduction process involved metal electrodeposition for the Fe II , Ni II and Zn II complexes. In the case of the Co II complex, the voltammetric response suggested a multistep decomposition process during the electrochemical reduction. Finally, a linear correlation between the oxidation potential of the ligand and the average M–N bond length has been found, permitting the modification of the oxidation potential by selection of the metal centre.
Type of Medium:
Online Resource
ISSN:
1434-1948
,
1099-0682
DOI:
10.1002/ejic.v2020.17
DOI:
10.1002/ejic.202000120
Language:
English
Publisher:
Wiley
Publication Date:
2020
detail.hit.zdb_id:
1475009-0
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