Synthesis, structures and photophysical properties of phosphorus-containing silver 3,5-bis(trifluoromethyl)pyrazolates

Tetranuclear Copper(I) and Silver(I) Pyrazolate Adducts with 1,1'-Dimethyl-2,2'-bibenzimidazole: Influence of Structure on Photophysics

A reaction of a cyclic trinuclear copper(I) or silver(I) pyrazolate complex ([MPz]₃, M = Cu, Ag) with 1,1'-dimethyl-2,2'-bibenzimidazole (L) leads to the formation of tetranuclear adducts decorated by one or two molecules of a diimine ligand, depending on the amount of the ligand added (0.75 or 1.5 equivalents). The coordination of two L molecules stabilizes the formation of a practically idealized tetrahedral four-metal core in the case of a copper-containing complex and a distorted tetrahedron in the case of a Ag analog. In contrast, complexes containing one molecule of diimine possess two types of metals, two- and three-coordinated, forming the significantly distorted central M₄ cores. The diimine ligands are twisted in these complexes with dihedral angles of ca. 50-60°. A TD-DFT analysis demonstrated the preference of a triplet state for the twisted 1,1'-dimethyl-2,2'-bibenzimidazole and a singlet state for the planar geometry. All obtained complexes demonstrated, in a solution, the blue fluorescence of the ligand-centered (LC) nature typical for free diimine. In contrast, a temperature decrease to 77 K stabilized the structure close to that observed in the solid state and activated the triplet states, leading to green phosphorescence at ca. 500 nm. The silver-containing complex Ag₄Pz₄L exhibited dual emission from both the singlet and triplet states, even at room temperature.

Emissive silver(i) cyclic trinuclear complexes with aromatic amine donor pyrazolate derivatives: way to efficiency

Cyclic silver(i) fluorinated pyrazolates containing triphenylamine and carbazole moieties are emissive in solution and the solid state, giving the first example of silver pyrazolate adducts emissive in solution at room temperature.

Bis(isonicotinamide-κN)silver(I) trifluoromethanesulfonate acetonitrile disolvate

The reaction of silver(I) triflouro­methane­sulfonate with isonicotinamide in aceto­nitrile produces a polymeric structure held together by discrete hydrogen bonds, regium bonds between the metal atom and the solvent mol­ecules, and metal–metal inter­actions.

The central Ag^I atom of the title salt, [Ag(INAM)₂](CF₃SO₃)·2CH₃CN, where INAM is isonicotinamide (C₆H₆N₂O), is twofold coordinated by the pyridine N atoms of two isonicotinamide ligands creating a slightly distorted linear mol­ecular geometry. The formation of polymeric chains {[Ag(INAM)₂]⁺}_n, held together by discrete hydrogen bonds through the amide group of the INAM ligand leaves voids for non-coordinating aceto­nitrile mol­ecules that inter­act the silver metal center via regium bonds.

A Computational Study of Metallacycles Formed by Pyrazolate Ligands and the Coinage Metals M = Cu(I), Ag(I) and Au(I): (pzM)n for n = 2, 3, 4, 5 and 6. Comparison with Structures Reported in the Cambridge Crystallographic Data Center (CCDC)

The structures reported in the Cambridge Structural Database (CSD) for neutral metallacycles formed by coinage metals in their valence (I) (cations) and pyrazolate anions were examined. Depending on the metal, dimers and trimers are the most common but some larger rings have also been reported, although some of the larger structures are not devoid of ambiguity. M06-2x calculations were carried out on simplified structures (without C-substituents on the pyrazolate rings) in order to facilitate a comparison with the reported X-ray structures (geometries and energies). The problems of stability of the different ring sizes were also analyzed.

Synthesis, structures and luminescence of multinuclear silver(i) pyrazolate adducts with 1,10-phenanthroline derivatives

A set of silver(i) 3,5-bis(trifluoromethyl) pyrazolate adducts with 1,10-phenanthroline (L²), 2,9-dimethyl-1,10-phenanthroline (neocuproine, L³) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine, L⁴) was synthesized starting from trimeric silver pyrazolate Ag₃Pz₃. Reactions with sterically hindered L³ and L⁴ cause the destruction of the original trimeric core, yielding a dinuclear Ag₂Pz₂ cycle with an unprecedented chair configuration for L³, while bathocuproine L⁴ leads to the drastic rearrangement of the silver pyrazolate core into cationic Ag(L⁴)₂ and anionic Ag₅Pz₆ subunits. All complexes obtained exhibit phosphorescence in the solid state. Time-dependent density functional theory calculations demonstrate their different possible emission processes, explaining their emission behavior as well as their lifetimes.