Tripyrrinatocadmium Complexes: Enforcing Supramolecular Aggregation by a Large Ion

• Published in: European Journal of Inorganic Chemistry 2007-03, Vol.2007 (7), p.1010-1019
• Main Authors: Bröring, Martin, Prikhodovski, Serguei, Tejero, Esther Cónsul, Köhler, Silke
• Format: Article
• Language: English
• Subjects: Cadmium; Porphyrinoids; Supramolecular chemistry; Tripyrrin
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.200601016

A newly developed method for the preparation of free base tripyrrin ligands HTrpy by cyanide‐promoted demetalation of nickel chelates TrpyNiNCO was used in order to explore the chemistry of cadmium tripyrrins TrpyCdX with a variety of anionic co‐ligands X. The introduction of the large CdII ion into the tripyrrin N3 coordination site was accomplished by the use of cadmium acetate as the metal precursor. Ligand exchange experiments using sodium salts of different anions disclose a marked tendency for pentacoordination, which is achieved either by the formation of chelates or of 1D coordination polymers that form as a consequence of the size of the central metal. The attempted introduction of chlorido, iodido, or cyanato ligands thus leads mainly to decomposed material, while the use of 1,1,1‐trifluoracetylacetonate, salicylate, and acetate ligands results in stable, pentacoordinate and monomeric complexes with the external ligand bound as a four‐ or six‐membered O,O‐chelate ring. With the pseudohalogenido ligands thiocyanate, selenocyanate, and azide as well as with the weakly coordinating trifluoroacetate 1D coordination polymers with a variety of chain structures were obtained and investigated by X‐ray diffraction studies. Interestingly TrpyCdN3 is present in the crystal as a coordinatively and hydrogen‐bonded methanol adduct with a dimeric repeating subunit. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)