Cooperative Interactions in the Second Coordination Sphere of Pyridazine/Pyridine Containing Polyazaheterocyclic Iron(II) Complexes Favor Protonation

Abstract

The new pyridazine containing iron complexes, [N,N,N′,N′-tetrakis(3-pyridazylmethyl)propylenediamine]iron-(II)(PF 6 ) 2 (1) and [N,N′-bis(2-pyridazylmethyl)-N,N′-bis(2-pyridylmethyl)propylenediamine]iron(II) (PF 6 ) 2 (2) were synthesized and their reactivity towards protonation was compared to that of the analogous tetrapyridine complex [N,N,N′,N′-tetrakis(2pyridylmethyl)propylenediamine]iron(II)(PF 6 ) 2 (3). The solution and solid-state structures were confirmed by NMR and X-ray crystallographic studies. For 1-3, the ligands bind in a hexa- [a]