Molecular recognition of redox-switchable bis-crown moieties assembled on a dicobalt complex

Synthesis, characterization and molecular structure of a dinuclear uranyl complex supported by N,N′,N″,N′″-tetra-(3,5-di-tert-butylsalicylidene)-1,2,4,5-phenylenetetraamine

The preparation, characterization and the molecular structure of a dinuclear uranyl complex [(UO2)2L(OCMe2)2] supported by the bis-salophen ligand N,N′,N″,N′″-tetra-(3,5-di-tert-butylsalicylidene)-1,2,4,5-phenylenetetraamine (L4–) is described. [(UO2)2L(OCMe2)2] was prepared by reaction of uranyl nitrate with the neutral, protonated form of the ligand (H4L) in acetone. From a saturated acetone solution [(UO2)2L(OCMe2)2]·1.5(OCMe2) crystallizes triclinically, space group P1̅ with a = 1522.7(2), b = 1751.4(2), c = 1815.4(2) Å, α = 109.16(1), β = 99.29(1), γ = 105.29(1)° and Z = 2. Each uranium atom is surrounded in a distorted pentagonal bipyramidal fashion by two O and two N atoms of the salicylidene units, one O atom of an acetone ligand, and the two oxo groups. The cyclic voltammogram of [(UO2)2L(OCMe2)2] shows two quasi-reversible redox processes centered at +0.57 V and +0.82 V vs. Fc+/Fc attributed to the sequential oxidation of the coordinating phenolates to phenoxyl radicals. The crystal structure of an ethanol solvate of H4L was also determined by X-ray crystallography. H4L·5EtOH: triclinic, space group P1̅, a = 1003.4(3), b = 1187.7(3), c = 1905.1(5) Å, α = 75.75(2), β = 78.74(2), γ = 66.66(2)°, Z = 1.