The Chlorido-Bismuth Dication: A Potent Lewis Acid Captured in a Hepta-Coordinate Species with a Stereochemically Active Lone Pair.

The stabilization of simple, highly reactive cationic species in molecular complexes represents an important strategy to isolate and characterize compounds with uncommon or even unprecedented structural motifs and properties. Here we report the synthesis, isolation, and full characterization of chlorido-bismuth dications, stabilized only by monodentate dimethylsulfoxide (dmso) ligands: [BiCl(dmso)6][BF4]2 (1) and [BiCl(µ2-dmso)(dmso)4]2[BF4]4 (2). These compounds show unusual distorted pentagonal bipyramidal coordination geometries along with high Lewis acidities and have been analyzed by multinuclear NMR spectroscopy, elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, and density functional theory calculations. Attempts to generate the bromido- and iodido-analogs gave dmso-stabilized tricationic bismuth species.

Heavy silylchalcogenido lanthanates synthesis Ph4P[Cp3La-ESiMe3] (E = S, Se, and Te) via fluoride-induced demethylation of dimethylcarbonate to Ph4P[OCO2Me] key intermediate.

We report a new high-yield synthesis of so far not accessible tetraphenylphosphonium methylcarbonate Ph4P[OCO2Me] via solvothermal fluoride-induced demethylation and MeF elimination at Me2CO3 (DMC) by Ph4P-F, structurally characterized as λ5-fluorophosphoran by XRD. The synthetic value of Ph4P[OCO2Me] key compound for preparing nearly all kinds of other Ph4P[anion] salts with perfectly crystallizing (not symmetry frustrated) cation is demonstrated by examples beyond ionic liquid research: a complete set of silylchalcogenide salts Ph4P[ESiMe3] (E = S, Se, and Te) including the first example of a structurally characterized non-coordinating, naked [Te-SiMe3]- anion is presented. With this set of soft Lewis bases and metal organic Lewis acids [Cp3La] at hand, a comprehensive series of crystalline 1 : 1 lanthanate complexes Ph4P[Cp3La-ESiMe3] has been prepared. Their structural features and trends such as complexation induced Si-E bond elongation and a pronounced trend in La-E-Si bond angle contraction with E = S < Se < Te are discussed. Heteronuclear 1H, 13C, 29Si, and 139La NMR studies provide a set of 139La NMR shifts for homologs of heavy chalcogen-lanthanum complexes.

Synthesis, Structures, and Magnetic Properties of Two Coordination Assemblies of Mn(III) Single Molecule Magnets Bridged via Photochromic Diarylethene Ligands.

Two new coordination assemblies were prepared by combining the open and close forms of 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorocyclopentene (H2dae) with [Mn2(saltmen)2(H2O)2](PF6)2, where H2saltmen = 2,2'-((1 E,1' E)-((2,3-dimethylbutane-2,3-diyl)bis(azaneylylidene)) bis(methaneylylidene))diphenol. From X-ray diffraction analyses, the complexes had the following formula: [Mn2(saltmen)2(dae-open)] (1open) and [Mn(saltmen)(dae-close)]·H2O·Et3N (1close). Both complexes crystallized in the C2/ c monoclinic space group. In 1open, dae-o2- behaves as a bidentate ligand attached to the outer Mn-saltmen monomer via the oxygen atom of carboxylato groups, whereas in 1close, the dae-c2- ligand behaves as a monodentate ligand attached to the external Mn-saltmen dimer by only one carboxylato group of the photochromic ligand. The complexes showed reversible photochromic responses to UV/vis light and showed single-molecule magnet-like behavior. The relaxation times and energy barriers of the metal complexes are clearly affected by UV/vis irradiation.

Enhancement of electrocatalytic abilities for reducing carbon dioxide: functionalization with a redox-active ligand-coordinated metal complex.

A binary system consisting of a ditopic planar pseudo-pincer ligand (qlca = quinoline-2-carbaldehyde (pyridine-2-carbonyl) hydrazone) coordinated to two metal centres affording [{Ru(bpy)2}(µ-qlca)NiCl2]Cl·4H2O·CH3OH (2) (bpy = 2,2'-bipyridine) is reported. The Ni2+ moiety acts as the electrocatalytic active site for CO2 reduction to CO. The turnover frequency (TOF) increased from 0.83 s-1 for [Ni(qlca)Cl2] (3) to 120 s-1 for 2, and the overpotential is 350 mV less than that for 3 due to the electronic influence of the {Ru(bpy)2}2+ moiety on the catalytic active site.

Photo-activation of Single Molecule Magnet Behavior in a Manganese-based Complex.

A major roadblock to fully realizing molecular electronic devices is the ability to control the properties of each molecule in the device. Herein we report the control of the magnetic properties of single-molecule magnets (SMMs), which can be used in memory devices, by using a photo-isomerizable diarthylenthene ligand. Photo-isomerization of the diarylethene ligand bridging two manganese salen complexes with visible light caused a significant change in the SMM behavior due to opening of the six-membered ring of diarylethene ligand, accompanied by reorganization of the entire molecule. The ring-opening activated the frequency-dependent magnetization of the complex. Our results are a major step towards the realization of molecular memory devices composed of SMMs because the SMM behaviour can be turned on and off simply by irradiating the molecule.

Photo-control of the magnetic properties of Dy(III) and Ho(III) homometal coordination polymers bridged by a diarylethene ligand.

Two-dimensional Dy(III) and Ho(III) homometal coordination polymers containing the photochromic ligand 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorocyclopentene (DTE) with the general formula [Ln2(DTE)3(bipyridine)2(H2O)2]n (Ln = Dy and Ho) were obtained, and the magnetic properties of their open (Dy-o and Ho-o) and closed forms (Dy-c and Ho-c) were investigated. The Dy complexes exhibited slow magnetic relaxation without an external dc field. The magnetic properties of the Dy complexes were irreversibly affected by the conformation of the ligand.