Tripyrrinatocadmium Complexes: Enforcing Supramolecular Aggregation by a Large Ion

Abstract

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)

Pyrrolyl‐Appended Zinc Porphodimethenes: Branched Oligopyrrole Products From the Templated One‐Pot Isoporphyrin Synthesis

“…Structural similarities, however, are found with the cadmium tripyrrins carrying carboxylate coligands. [13] Here it can be observed that in the case of distorted tetragonal-pyramidal coordination, the axial position is significantly closer to the metal atom than the equatorial one. This observation is similar for a dinuclear nickel tripyrrin with a bridging oxalato ligand, too.…”

“…CHN analyses were performed on an Elementar Vario MicroCube instrument. 1 H-, 13 C-and 19 F-NMR spectra were obtained on a Bruker Avance II 300, a Bruker Avance III HD 500 and a Bruker Avance II 600 spectrometer at room temperature. Chemical shifts (δ) are given in ppm relative to TMS and referenced against residual protio solvent resonances.…”

“…1 H NMR (300 MHz, CDCl 3 ): δ = 8.05 (s, 6H, aryl-H), 7.61 (t, J = 1.19, 4H, pyrrolyl-H), 6.55 (dd, J = 4.41, 1.12 Hz, 4H, pyrrolyl-H), 6.48 ppm (dd,J = 4.20,1.38 Hz,4H,. 13 C NMR (75 MHz, CDCl 3 ): δ = 151. 1, 144.1, 140.9, 139.9, 132.6, 131.2, 130.8, 125.0, 122.5, 121.4, 118.3 ppm.…”

“…s, exo-pyr-H). 13 C NMR (75 MHz, THF-d 8 ): δ = 164. 85, 151.30, 151.13, 148.54, 147.31, 147.13, 147.08, 146.49, 146.39, 142.14, 141.11, 140.49, 139.30, 139.20, 136.52 (15 × q), 158.40, 149.84, 137.12, 136.28, 132.43, 131.61, 131.16, 131.10, 130.01, 129.55, 129.49, 129.07, 128.53, 128.12, 128.11, 127.43, 127.01, 125.65, 122.04, 118.76, 118.25, 116.21, 110.71, 107.12 (24 × CH), 55.52 ppm (iso-C).…”

SNS versus SNN Pincer Ligands: Electrochemical Studies and Their Palladium(II) Complexes as Electro‐Catalyst for Proton Reduction

“…Pincer complexes have been synthesized since the early 1970 s, [1] and new designs (Scheme 1) continue to emerge due to their rich chemistry. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Complexes of pincer ligands have been employed as crystalline switches, as sensors and most commonly as precatalysts for numerous transformations. [17] Pincer systems are ubiquitous due to their relative ease of synthesis, and most of the reported systems are planar, due to the aromatic backbone that is commonly used.…”