Iron and Silver Complexes of 4‐(Imidazol‐1‐yl)‐2,6‐di(pyrazol‐1‐yl)‐pyridine ( L ), Including a [Fe 3 (µ‐F) 2 F 6 L 8 ] + Assembly

Treatment of 2,4,6‐trifluoropyridine with sodium imidazolate, then 2 equiv. sodium pyrazolate, in two reaction steps yields the title ligand L in 40 % overall yield. Crystalline [Fe L 2 ][BF 4 ] 2 and [Fe L 2 ][ClO 4 ] 2 are isostructural high‐spin complexes, with highly twisted six‐coordinate geometries and pendant imidazolyl groups. Conversely, [Ag(µ‐ L )]BF 4 · 0.5MeCN is a linear coordination polymer of distorted square planar silver ions linked by κ 1 :κ 3 ,µ‐ L ligands. Some samples of [Fe L 2 ][BF 4 ] 2 were contaminated by [Fe III 3 (µ‐F) 2 F 6 L 8 ]BF 4 , which was prepared in pure form following reaction of Fe[BF 4 ] 2 · 6H 2 O, Na 3 [FeF 6 ] and L in appropriate ratios. The linear [{ trans ‐FeF L 4 } 2 (µ‐F) 2 FeF 4 ] + assembly is supported by monodentate L ligands coordinated through their imidazolyl donors, and donating C–H ···· F interactions to the central [FeF 6 ] 3– moiety. The cluster exhibits moderate antiferromagnetic coupling between its iron(III) centres.