Crystallographic studies on a series of salts of 2,3,7-trihydroxy-9-phenyl-fluorone

2,3,7-Trihydroxy-9-phenyl-fluorone (hereafter H3Z) has been synthesised in its H4Z+, H3Z, H2Z- and Z3- protonation states. X-ray crystal structure determinations have been carried out for (H4Z)(HSO4), H3Z, [EtiPr2NH]H2Z, solvated (PPh4)H2Z and solvated K3Z. In each of these salts the 9-phenyl group adopts a different orientation so as to be involved in intermolecular aromatic interactions. The 3- and 6-phenolic carbon-oxygen bond lengths show that double bond character can be delocalised from the ketone to the deprotonated phenoxide across the conjugated π system of the fluorone.</p

Synthesis, structure and magnetic properties of a novel Tb4 spin cluster and synthesis of a Tb chain

The syntheses of two new polynuclear TbIII compounds are reported. A tetranuclear complex [Tb4(H2L)2(H4L)2(OAc)8] (1), with H4L=2-((2-hydroxy-benzylidene)-amino)-2-hydroxy-methyl-propane-1,3-diol, has a butterfly-type structure, while [Tb(OAc)3MeOH]∞ (2) is a linear chain. A novel binding mode for H2L2− is observed in 1, with two alkoxides each bridging three TbIII ions. The magnetic properties of 1 are determined by the superposition of the ligand field split 7F6 states of TbIII single-ions located on two crystallographically distinct sites. Weak antiferromagnetic exchange interactions possibly contribute to the lowering of the magnetic moment at the lowest temperatures. © 2007, Elsevier Ltd

Coordination polymers of 2,5-dihydroxybenzoquinone and chloranilic acid with the (10,3)- A topology

Crystalline compounds of general composition (NBu4) 2[MII2(dhbq)3] (where M = Mn, Fe, Co, Ni, Zn, and Cd and dhbq2- is the dianion of 2,5- dihydroxybenzoquinone) are obtained by reaction of the divalent metal acetate (or the sulfate in the case of Fe) with 2,5-diaminobenzoquinone and an excess of NBu4Br in aqueous solution at 115 °C in sealed tubes. The dhbq2- ligand is generated in situ by hydrolysis of the 2,5-diaminobenzoquinone. We have been unable to obtain these compounds in a crystalline form suitable for single crystal X-ray diffraction studies directly from H2dhbq itself. A structural feature common to this series is the presence of two interpenetrating [MII2(dhbq) 3]2- coordination networks, each with the chiral (10,3)-a topology, with the two independent nets being of opposite hand - unprecedented circumstances for dhbq-based coordination polymers. Crystals of the same zinc compound as that obtained above from 2,5-diaminobenzoquinone can alternatively be obtained by in situ aerial oxidation of 1,2,4,5-tetrahydroxybenzene in the presence of Zn(OAc)2 and NBu4Br in aqueous methanol at room temperature. Analogous in situ aerial oxidation of 1,2,4,5-tetrahydroxy-3, 6-dichlorobenzene in the presence of Mn(OAc)2 and NBu4Br affords crystalline samples of the chloranilate (NBu4) 2[MnII2(can)3], which contains two interpenetrating (10,3)-a [MnII2(can)3] 2- networks of opposite hand.</p

In Situ Spectroelectrochemical Investigations of Ru^II Complexes with Bispyrazolyl Methane Triarylamine Ligands

The synthesis and characterization of two triarylamine ligands, 4-(di(1H-pyrazol-1-yl)methyl)-N-(4-(di(1H-pyrazol-1-yl)methyl)phenyl)-N-phenylaniline (TPA-2bpm) and tris(4-(di(1H-pyrazol-1-yl)methyl)phenyl)amine (TPA-3bpm), containing the bispyrazolylmethane moiety and its RuII terpyridine complexes are presented. The redox properties of the ligands and RuII complexes are explored in detail through cyclic and square-wave voltammetry in addition to in situ UV-vis-near infrared, electron paramagnetic resonance, and fluorescence spectroelectrochemistry. It was demonstrated that the triarylamine radical cation was able to be generated, and further, TPA-2bpm underwent an electrochemically induced dimerization process. </jats:p