The Fe(II) complexes with a doubly deprotonated polydentate acylhydrazone: crystal structure of the first diamagnetic #mu#-oxo-diiron(III) complex

摘要

Heavy metal ion extractants 2-nonyl-8-hydroxyquinoline (LH1) and 7-nonyl-8-hydroxy-quinaldine (LH2) yield complexes with Zn(II) (LH1 and LH2) and Cd(II) ions (LH2). X-ray crystal structures indicate that the Zn(II) complex of LH1 (la) as well as the Cd(II) complex of LH2 (2b) are of binuclear five-coordinated type with M2L4 stoichiometry (M = Zn, Cd) whereas the Zn(II) complex of LH2 (2a) is a mononuclear four-coordinated ML~ type. The binuclear complexes la and Zb have symmetric build-up. Due to H metal distances observed in the complexes the coordination geometries are also analyzed by the perusal of the Cambridge crystallographic database. There are slightly differing feeble C—H~M interactions and a differing pattern of weak C—H0 contacts in all three complexes. The different selectivity of ligand LH2 towards Cd2 + and Zn2 ~, as well as the selectivity of LH1 for both Cd2 + and Zn2 + might possibly be explained by the packing differences in the three crystal structures.