Outbreak of SARS-CoV-2 B.1.617.2 (delta) variant in a nursing home 28 weeks after two doses of mRNA anti-COVID-19 vaccines: evidence of a waning immunity.

Objectives: To describe a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.617.

Monitoring of the Pre-Equilibrium Step in the Alkyne Hydration Reaction Catalyzed by Au(III) Complexes: A Computational Study Based on Experimental Evidences.

The coordination ability of the [(ppy)Au(IPr)] fragment [ppy = 2-phenylpyridine, IPr = 1,3-(2,6-di-isopropylphenyl)-imidazol-2-ylidene] towards different anionic and neutral X ligands (X = Cl, BF, OTf, HO, 2-butyne, 3-hexyne) commonly involved in the crucial pre-equilibrium step of the alkyne hydration reaction is computationally investigated to shed light on unexpected experimental observations on its catalytic activity. Experiment reveals that BF and OTf have very similar coordination ability towards [(ppy)Au(IPr)] and slightly less than water, whereas the alkyne complex could not be observed in solution at least at the NMR sensitivity. Due to the steric hindrance/dispersion interaction balance between X and IPr, the [(ppy)Au(IPr)] fragment is computationally found to be much less selective than a model [(ppy)Au(NHC)] (NHC = 1,3-dimethylimidazol-2-ylidene) fragment towards the different ligands, in particular OTf and BF, in agreement with experiment.

The mechanism of the gold(I)-catalyzed Meyer-Schuster rearrangement of 1-phenyl-2-propyn-1-ol 4- cyclization.

With the aim of rationalizing the experimental counterion- and solvent-dependent reactivity in the gold(i)-catalyzed Meyer-Schuster rearrangement of 1-phenyl-2-propyn-1-ol, a computational mechanistic study unraveled the unexpected formation of a gold-oxetene intermediate via commonly unfavorable 4-endo-dig cyclization triggered by the counterion in low polarity solvents.

CNN pincer ruthenium complexes for efficient transfer hydrogenation of biomass-derived carbonyl compounds.

The ligand HCNNOMe (6-(4-methoxyphenyl)-2-aminomethylpyridine) is easily prepared from the commercially available 6-(4-methoxyphenyl)pyridine-2-carbaldehyde by the reaction of hydroxylamine and hydrogenation (H2, 1 atm) with Pd/C. The pincer complexes cis-[RuCl(CNNOMe)(PPh3)2] (1) and [RuCl(CNNOMe)(PP)] (PP = dppb, 2; and dppf, 3) are synthesized from [RuCl2(PPh3)3], HCNNOMe and PP (for 2 and 3) in 2-propanol with NEt3 at reflux and are isolated in 85-93% yield. Carbonylation of 1 (CO, 1 atm) gives [RuCl(CNNOMe)(CO)(PPh3)] (4) (79% yield) which cleanly reacts with Na[BArf4] and PCy3, affording the cationic trans-[Ru(CNNOMe)(CO)(PCy3)(PPh3)][BArf4] (5) (92% yield).

Preparation of monocarbonyl ruthenium complexes bearing bidentate nitrogen and phosphine ligands and their catalytic activity in carbonyl compound reduction.

Monocarbonyl complexes [RuCl(CO)(PR)(NN)] (R = Cy, NN = en 1, ampy 2; R = iPr; NN = en 3) have been prepared in a one pot reaction from [RuCl(CO)(dmf)(PPh)], PR and the NN ligand in CHCl. Treatment of [Ru(OAc)(CO)(PPh)] with NN ligands in methanol gives the cationic derivatives [Ru(OAc)(CO)(PPh)(NN)]OAc (NN = en 4, ampy 5) in which one acetate acts as a bidentate ligand, whereas the other is not coordinated. Diphosphine complexes [RuCl(CO)(PP)(PPh)] (PP = dppb 6, dppf 7, (R)-BINAP 8, (R,S)-Josiphos 9 and (R,R)-Skewphos 10) have been obtained starting from [RuCl(CO)(dmf)(PPh)] and the PP ligand in CHCl or toluene at reflux.