Cobalt molybdenum nitrides can be obtained from the oxidic precursor by reaction with gaseous ammonia. Despite the large number of works regarding catalytical properties of these compounds, there are relatively few reports about the initial transformation from oxide to nitride. In this work, the influence of the precursor structure on the active phase formation and catalytic properties of cobalt molybdenum nitrides is examined. Oxidic precursors were obtained by precipitation at different pH values controlled by the addition of aqueous ammonia. The parameters of the precipitation process affected the composition and properties of the materials. The ammonolysis of NH4Co2OH(MoO4)2·H2O was investigated in situ with the use of X-ray powder diffraction and thermogravimetry. The ammonia synthesis activity of the obtained catalysts was compared to the reference iron catalyst. The formation of the Co3Mo intermetallic phase was suggested as the factor governing high activity.

Rare-earth-metal (Ln) alkyl and aryl compounds feature highly reactive, thermally labile [Ln–C] s-bonds which result in rapid and violent decomposition in the presence of air and moisture. Nevertheless, such [Ln–C] moieties display important intermediate species in numerous organic transformations. Reagents containing [Ln–C] bonds are deliberately generated in situ like Imamoto-type reagents Ln(III)Cl3/RLi (routinely at low temperatures) or “heavy” lanthanide-Grignard compounds RLnX. Samarium(III)-alkyl species are supposed intermediates of SmI2-promoted Barbier-type carbon– carbon coupling reactions. Alkyl/aryl ligand exchange at Ln(III) centers has been identified as the crucial step of lanthanide–halogenexchange reactions. In the meantime, several such mixed alkyl/halogenido complexes, devoid of an ancillary ligand, could be isolated and scrutinized with regard to structure and reactivity. More recently, Ln(III)-alkylidene complexes could be accessed, structurally authenticated and successfully employed in Tebbe-like olefination reactions of ketones.

This work presents the synthesis and characterization of mono (1) and di-nuclear (2) imidazolium salts stabilized by [AuPPh3]+ fragments. The presence of the gold moiety induces a significant decrease in the carbenic proton's acidic character (high pKa). This high stability is consistent with the pronounced instability of the conjugate bases obtained through deprotonation using strong bases. The formation of carbene species is accompanied by the identification of a 1,2-rearrangement process in which a preference for the C-bound species over the N-bound species is observed. Experimental techniques such as NMR, single-crystal X-ray diffraction analysis, mass spectrometry, and computational calculations are employed to investigate the reactivity exhibited by the imidazolium salts. Additionally, the electrochemical properties of the two imidazolium salts were also investigated. This study reveals that both species 1 and 2 display two cathodic peaks which are related to two electro-chemical irreversible reduction events. The results obtained from both experimental and theoretical studies of this system reveal a strong tendency of the [AuPPh3]+ fragment to stabilize imidazolium salts. Additionally, they demonstrate the preference of this fragment for C-bound species over N-bound ones, with the former proving to be highly unstable even under severe conditions of air and moisture exclusion.

Bayoud disease poses a significant threat to date palm cultivation, and finding effective antifungal solutions is of paramount importance. Our research represents a substantial advance in this field, as we have succeeded in identifying a dinuclear complex displaying a high inhibition activity of 97 % at a low concentration of only 81.1 μmol/L.

Abstract

New coordination compounds made of two novel tetrazole and C,N-bipyrazole ligands, 2-(3,5,5′-trimethyl-1′H-[1,3′-bipyrazol]-1′-yl)acetonitrile (L1), and 1′-((1H-tetrazol-5-yl)methyl)-3,5,5′-trimethyl-1′H-1,3′-bipyrazole (HL2), were prepared and fully characterized by spectroscopic techniques. Their crystal structures were identified by single-crystal X-ray diffraction revealing mononuclear complexes: [Ni(L1)₃](ClO₄)₂ (1), [Cd(L1)₂Cl₂] (2), [Cu(HL2)(L2)]ClO₄ (3), [Cu(L2)₂] (4) and a dinuclear complex [Co₂(HL2)(L2)Cl₃] (5) comprising Co^II ions in octahedral and tetrahedral surrounding within the same unit. Noticeably, 3 and 4 show different architectural structures due to ligand deprotonation as well as the effect of the counter anion. All compounds demonstrated antimicrobial activity against Gram (+) bacteria Listeria innocua and Staphylococcus aureus, as well as Gram (−) bacteria such as Escherichia coli and Pseudomonas aeruginosa, and antifungal activity against pathogenic fungi Geotrichum candidum, Aspergillus niger, and Penicillium crustosum. Interestingly, a high inhibition activity of 97 % was reached for 5 with a low concentration of only 81.1 μmol/L against Fusarium oxysporum f. sp. Albedinis, which is commonly damaging palm trees crops.