Isolation of chloride- and hydride-bridged tri-iron and -zinc clusters in a tris(β-oxo-δ-diimine) cyclophane ligand

Abstract

A cyclophane ligand (H₆L) bearing three β-oxo-δ-diimine arms and the corresponding tri-iron and -zinc complexes in which the metal ions are bridged by either chlorides, viz. Fe₃Cl₃(H₃L) (1) and Zn₃Cl₃(H₃L) (2), or hydrides, viz. Fe₃H₃(H₃L) (3), Zn₃H₃(H₃L) (4), were synthesized and characterized. 1 adopts a chair-shaped C_3v-symmetric [Fe₃(μ-Cl)₃]³⁺ cluster wherein only one hemisphere of the ligand is metallated and the other three ketoimine sites remain protonated as evidenced by single crystal X-ray diffraction and vibrational and NMR spectroscopic analyses. 3 and 4 were synthesized by substitution of the bridging chlorides in 1 and 2 using KBEt₃H and are accessed with retention of the three protonated ketoimine sites.