Abstract
Five mononuclear tris‐chelate complexes of FeII, CoII, NiII and ZnII, containing the bidentate ligand 3‐methyl‐1‐(2‐pyridyl)imidazolyl‐2‐thione (L), have been synthesised and characterised, namely [MII(L)3](BF4)2, where M = Fe (1), Co (2), Ni (3) and Zn (4), and [FeII(L)3](PF6)2 {1‐(PF6)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 P1 space group, except for 1‐(PF6)2, which crystallises in the P21/c, as expected due to the different size and symmetry of the anion. The metal centre is found in a distorted meridional‐N3S3 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 FeII and CoII 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 CD3CN 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 FeII, NiII and ZnII complexes. In the case of the CoII 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.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.