The Goldilocks principle in action: synthesis and structural characterization of a novel {Cu4(\u3bc3-OH)4} cubane stabilized by monodentate ligands

A {Cu4(\u3bc3-OH)4} compound, where four copper(II) and four \u3bc3-bridging oxygen atoms occupy alternate corners of a slightly distorted cube, has been prepared and structurally characterized. This species, formulated as [Cu4(\u3bc3-OH)4(Htmpz)8](ClO4)4\ub71.5Et2O (Htmpz = 3,4,5-1H-trimethyl pyrazole), can be classified as belonging to type I Cu4O4 cubane complexes, and is better described as two CuII\u2013(\u3bc-OH)2\u2013CuII units held together by four long Cu\u2013O bonds. The central distorted cubane core is stabilized by neutral monodentate ligands (Htmpz) and perchlorate anions, as demonstrated by single-crystal X-ray structure analysis. The title compound was obtained by hydrolysis of a dinuclear methoxo-bridged species, [Cu(\u3bc-OCH3)(Htmpz)2]2(ClO4)2, which was prepared by reaction of [Cu(Htmpz)4(ClO4)2] with methanol. All these reactions represent a nice example of the Goldilocks principle in action in coordination chemistry, since each single actor (solvent, counteranion, and ligand) has the \u201cjust right\u201d electronic, steric or coordinative properties which determine the fate of the final products

Luminescent blue emissive bis(alkynyl) borane compounds with a N,O-coordinated ligand

Five bis(alkynyl)boranes with a (imidazo[1,5-a]pyridin-3-yl)phenolate ligand have been synthesized and characterized both in solution (1H, 13C, 11B, 19F NMR) and in the solid state (X-ray). All derivatives, differing for the substituent R (H, Me, OMe, CF3, NMe2) in the para position of the phenylacetylene moieties, displayed blue fluorescence emission in solution, linearly correlated to the electronic properties of the substituent R (i.e., its σp Hammett constant). High Stokes shifts and good quantum yields were recorded. Time-Dependent Density Functional Theory (TD-DFT) calculations were performed to describe the percentage contribution of each fragment of the molecule to the frontier orbitals. Electron Density Difference Maps (EDDMs) calculated for all derivatives allowed to explain the emissive properties of the studied compounds

Investigation of the structure and catalytic activity in olefin cyclopropanation of neutral and cationic dicopper complexes of 3,5-bis(pyridinylimino)benzoic acid.

Three neutral and one cationic copper(I) complexes with 3,5-bis(pyridinylimino)benzoic acid are synthesized and characterized in solution and in the solid state by a variety of spectroscopic techniques and X-ray crystallography. The compounds are tested for their catalytic activity in olefin cyclopropanation reactions by means of ethyl diazoacetate decomposition and prove to be moderately active with the ionic one being the most active and the most promising since for cyclohexene it reveals a considerable diastereoselectivity and a 90:10 exo:endo ratio of the final product

Quinoline-2-carbaldehyde

The title compound, C10H7NO, crystallizes with two almost planar mol­ecules (A and B) in the asymmetric unit (r.m.s. deviations = 0.018 and 0.020 Å). In the crystal, the A mol­ecules are linked by weak C—H⋯O inter­actions, thereby generating C(9) [001] chains. The B mol­ecules do not exhibit any directional bonding inter­actions

Dichlorido[2-(phenyl­imino­meth­yl)quinoline-N,N′]palladium(II)

In the title complex, [PdCl2(C16H12N2)], the PdII ion is coordinated by two N atoms [Pd—N 2.039 (2), 2.073 (2) Å] from a bidentate ligand and two chloride anions [Pd—Cl 2.2655 (7), 2.2991 (7) Å] in a distorted square-planar geometry. In the crystal, π–π inter­actions between the six-membered rings of the quinoline fragments [centroid–centroid distances = 3.815 (5), 3.824 (5) Å] link two mol­ecules into centrosymmetric dimers