An asymmetric cryptand for the site-specific coordination of 3d metals in multiple oxidation states

Jökel, J. and Nyßen, F. and Siegmund, D. and Apfel, U.-P.

Volume: 50 Pages: 14602-14610
DOI: 10.1039/d1dt02075g
Published: 2021

Bis-tren (tren = tris(2-aminoethyl)amine) azacryptands were previously studied profoundly for the coordination of two +iimetals and subsequent binding of substrates within their cavity. Likewise, cryptates including metals in different oxidations states were reported with the rather unstable hexa-imine analogues but also revealed only little stability. In this work, we report the synthesis of an asymmetric hexa-amine cryptand analogue by selectively exchanging three of the secondary amines of one binding site with sulphur atoms. We show that the presence of two distinct binding sites allows for the selective formation of stable dinuclear complexes of metals with different oxidation numbers and present the formation of distinct CuICoII, CuINiIIand CuICuIIIcryptates. © The Royal Society of Chemistry 2021.

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