Controlled Access to Mixed‐Metal Pyridazine‐Linked Cryptates

The pyridazine‐linked cryptand L [formed by the 3+2 condensation of 3,6‐diformylpyridazine with tris(2‐aminoethyl)amine (tren)] has been used to generate a series of heterodinuclear cryptates by a one‐pot two‐step method. The cryptates [Mn II Cu I L](ClO 4 ) 2 (BF 4 ), [Fe II Cu I L](BF 4 ) 3 ·CH 3 CN and [Ni II Cu I L](BF 4 ) 3 ·H 2 O have been structurally characterized, with elemental analyses and mass spectroscopic data providing further evidence of their heterodinuclear nature. The synthesis, structures and characterisation of the corresponding mononuclear cryptates [M II L](X) 2 (M = Mn, Fe, Ni, X = BF 4 − or ClO 4 − ) are also reported, along with the synthesis and characterisation of the homodinuclear dizinc( II ) and disodium( I ) cryptates, [Zn 2 L](ClO 4 ) 4 and [Na 2 L](CF 3 SO 3 ) 2 . Electrochemical studies on the heterodinuclear cryptates in CH 3 CN indicate that the presence of the divalent cation influences the electrochemical potential and reversibility of the Cu I → Cu II oxidation with the redox potential of the Cu I /Cu II couple being inversely correlated with the distance between the two metal ions in the solid state as determined by X‐ray crystallography. The previously synthesised [Co II Cu I L](BF 4 ) 3 is an exception to this trend, probably due to oxidation of the Co II ion prior to that of the Cu I ion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)