Dalton Transactions

doi: 10.1039/b618162gpmid: N/A

doi: 10.1039/b618164npmid: N/A

Fajula, François

doi: 10.1039/b615187fpmid: 17200747

Pseudomorphic transformation is introduced as an effective and versatile method to independently optimize the morphology of the grains and the structural properties of mesostructured silicas. In this account a short overview is given of the preparation of MCM-41 and MCM-48 mesophases as non-aggregated and homogeneously distributed particles with sizes ranging from 5 to 800 µm.

Brewer, Cynthia T.; Brewer, Greg; Butcher, Ray J.; Carpenter, Everett E.; Schmiedekamp, Ann M.; Viragh, Carol

doi: 10.1039/b613282kpmid: 17200748

Reaction of iron() and the 3 : 1 Schiff base condensate of 5-methylpyrazole-3-carboxaldehyde and tris(2-aminoethyl)amine in air gives a pseudo-dimer complex with a triple helix structure made of Δ–Δ and Λ–Λ pairings of spin crossover iron() and low spin iron() cations that are held together by three π–π and hydrogen bonding interactions.

Yajima, Tatsuo; Takamido, Reiko; Shimazaki, Yuichi; Odani, Akira; Nakabayashi, Yasuo; Yamauchi, Osamu

doi: 10.1039/b612394epmid: 17200749

Ternary Cu() complexes containing an aromatic diimine (DA = di(2-pyridylmethyl)amine (dpa), 4,4′-disubstituted 2,2′-bipyridine (Ybpy; Y = H (bpy), Me, Cl, N(Et), CONH or COOEt) or 2,2′-bipyrimidine) and an aromatic amino acid (AA = -phenylalanine (Phe), -substituted phenylalanine (XPhe; X = NH, NO, F, Cl or Br), -tyrosine (Tyr), -tryptophan (Trp) or -alanine (Ala)) were characterized by X-ray diffraction, spectroscopic and potentiometric measurements. The structures of [Cu(dpa)(Trp)]ClO·2HO and [Cu((CONH)bpy)(Phe)]ClO·HO in the solid state were revealed to have intramolecular π–π interactions between the Cu()-coordinated aromatic ring moiety, Cu(DA) (Mπ), and the side chain aromatic ring of the AA (Lπ). The intensities of Mπ–Lπ interactions were evaluated by the stability constants of the ternary Cu() complexes determined at 25 °C and = 0.1 M (KNO), which revealed that the stability enhancement of the Cu(DA)(AA) systems due to the interactions is in the order (CONH)bpy < bpy < Mebpy < (EtN)bpy with respect to DA. The results indicate that the electron density of coordinated aromatic diimines influences the intensities of the stacking interactions in the Cu(DA)(AA) systems. The Mπ–Lπ interactions are also influenced by the substituents, X, of Lπ and are in linear relationship with their Hammett values with the exception of X = Cl and Br.

Suzuki, Takayoshi; Fujiiwara, Katsuhiro; Takagi, Hideo D.; Kashiwabara, Kazuo

doi: 10.1039/b612025cpmid: 17200750

Several new cobalt() complexes containing (3-aminopropyl)dimethylphosphine (pdmp) have been prepared, and their molecular structures have been determined. A dichloro complex of (,)-(,)-[CoCl(pdmp)]PF () was prepared from -[CoCl(py)]Cl·6HO and pdmp. X-Ray crystallography confirmed the ()- conformation of two six-membered pdmp chelate rings in , while the analogous 1,3-bis(dimethylphosphino)propane (dmpp) complex -[CoCl(dmpp)]ClO () exhibited the ()- conformation. Substitution reactions of for ethane-1,2-diamine (en), pentane-2,4-dionate (acac), and ,-dimethyldithiocarbamate (dtc) gave the mixed-ligand tris(chelate)-type complexes of [Co(en)(pdmp)]Cl(PF) (), [Co(acac)(pdmp)](PF) (), and [Co(dtc)(pdmp)](PF) [ = 1 () or 2 ()], respectively. The conformer of the complex cation in was assigned as ·· by X-ray analysis. In the case of the acac complex , both (,) () and (,) () isomers were isolated, and the complex cations were characterized as - and - conformers, respectively, with respect to the six-membered pdmp chelate rings. These conformers coincide with the most stable ones anticipated by the DFT optimum geometry calculations. In the crystal structure of (,)-[Co(dtc)(pdmp)](BPh) (′) one of the pdmp chelate rings adopted a - () conformation, which reduced the intramolecular steric ring–ring interaction effectively. The DFT optimized geometries for several isomers and/or conformers of [CoCl(pdmp)] were compared.

Sakthivel, Ayyamperumal; Pedro, Filipe M.; Chiang, Anthony S. T.; Kühn, Fritz E.

doi: 10.1039/b611550kpmid: 17200751

Cyclopentadienyl ruthenium phosphane and carbene complexes are grafted on the surface of mesoporous SBA-15 molecular sieves through an aminosilane linker. The nature of the support after the grafting is examined by powder XRD, TEM and N adsorption/desorption analysis. Elemental analysis, FT-IR, DRIFTS, TG-MS and MAS-NMR studies confirm the successful grafting of the complexes on the surface. The grafted materials are applied for catalytic aldehyde olefination and cyclopropanation.

Christlieb, Martin; Cowley, Andrew R.; Dilworth, Jonathan R.; Donnelly, Paul S.; Paterson, Brett M.; Struthers, Harriet S. R.; White, Jonathan M.

doi: 10.1039/b612907bpmid: 17200752

Zinc and copper bis(thiosemicarbazonato) complexes containing more than one metal centre have been prepared with a view to examining their application for molecular imaging. The zinc complexes are fluorescent with excitation and emission at relatively long wavelengths. The dinuclear copper complex undergoes two sequential, quasi-reversible reductions.

Isele, Katharina; Gigon, Fabienne; Williams, Alan F.; Bernardinelli, Gérald; Franz, Patrick; Decurtins, Silvio

doi: 10.1039/b614424apmid: 17200753

A survey of the crystal structures containing simple {MO} cubane units is reported. It shows that the average M–M distance in these complexes is relatively constant for a given metal ion M. The structures are all distorted from the idealised cube to a structure, and most show a further distortion which, however, usually maintains some elements of symmetry. A system for classifying the different types of ligand in these complexes is proposed. Two new cubanes of cobalt() and nickel() with the ligand (,)-bis-1,2-(1-methylbenzimidazol-2-yl)ethane-1,2-diol, (,)- or its enantiomer have been isolated and the crystal structure of the cobalt() complex confirms the cubane structure. Electronic, CD and H NMR spectra and magnetic susceptibility data are reported. The magnetic data for these and other compounds in the literature are discussed in terms of the structural parameters.

Cuevas, Alicia; Kremer, Carlos; Hummert, Markus; Schumann, Herbert; Lloret, Francesc; Julve, Miguel; Faus, Juan

doi: 10.1039/b611888gpmid: 17200754

Three novel Re() compounds, the mononuclear complex BuN[ReBr(Hpyzc)] () and the heterobimetallic complexes [ReBr(µ-pyzc)M(dmphen)]·2CHCN [M = Co (), Ni ()] (Hpyzc = 2-pyrazinecarboxylic acid, dmphen = 2,9-dimethyl-1,10-phenanthroline), have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. The structure of consists of [ReBr(Hpyzc)] complex anions and tetrabutylammonium cations, BuN. The Re() is surrounded by five bromide anions and a N-donor Hpyzc monodentate ligand, in a distorted octahedral environment. The structures of and consist of dinuclear units [ReBr(µ-pyzc)M(dmphen)], with the metal ions linked by a pyzc bridge ligand, being bidentate toward M() and monodentate toward Re(). The environment of Re() is the same as in , whereas M() is six-coordinate, being surrounded by four nitrogen atoms of two bidentate dmphen ligands and one oxygen atom and one nitrogen atom of the pyzc anion. The magnetic properties of were investigated in the temperature range 2.0–300 K. shows the expected magnetic behavior for a mononuclear Re() complex with a weak intermolecular antiferromagnetic coupling at low temperatures. The bimetallic complexes exhibit an intramolecular ferromagnetic coupling between Re() and the M() ion (Co, Ni).