New Copper Complexes with N,O-Donor Ligands Based on Pyrazole Moieties Supported by 3-Substituted Acetylacetone Scaffolds

• Published in: Molecules (Basel, Switzerland) Vol. 29; no. 3; p. 621
• Main Authors: Del Gobbo, Jo', Santini, Carlo, Dolmella, Alessandro, Li, Zhenzhen, Caviglia, Miriam, Pellei, Maura
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.01.2024
• Subjects: Antiviral agents; Chemical tests and reagents; Copper; Heterocyclic compounds; Ketones; Ligands; pyrazole; spectroscopy; X-ray; β-diketone; United Kingdom; pyrazole; copper; X-ray; spectroscopy; β-diketone
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules29030621

The new 3-monosubstituted acetylacetone ligands, 3-(phenyl(1 -pyrazol-1-yl)methyl)pentane-2,4-dione (HL ) and 3-((3,5-dimethyl-1 -pyrazol-1-yl)(phenyl)methyl)pentane-2,4-dione (HL ), were synthesized and used as supporting ligands for new copper(II) and copper(I) phosphane complexes of the general formulae [Cu(HL ) (L ) ] and [Cu(PPh ) (HL )]PF (X = Pz (pyrazole) or PzMe (3,5-dimethylpyrazole)), respectively. In the syntheses of the Cu(I) complexes, the triphenylphosphine coligand (PPh ) was used to stabilize copper in the +1 oxidation state, avoiding oxidation to Cu(II). All compounds were characterized by CHN analysis, H-NMR, C-NMR, FT-IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). The ligands HL ( ) and HL ( ) and the copper complex [Cu(PPh ) (HL )]PF ( ) were also characterized by X-ray crystallography. The reactivity of these new compounds was investigated and the new compounds 4-phenyl-4-(1 -pyrazol-1-yl)butan-2-one ( ) and 4-(3,5-dimethyl-1 -pyrazol-1-yl)-4-phenylbutan-2-one ( ) were obtained in basic conditions via the retro-Claisen reaction of related 3-monosubstituted acetylacetone, providing efficient access to synthetically useful ketone compounds. Compound was also characterized by X-ray crystallography.