Two phenoxy-ketimines ligands, 2-(1-(benzylimino)ethyl)phenol (HL^BSMe) and 2-((benzylimino)(phenyl)methyl)phenol (HL^BSPh), were synthesized and used as supporting ligands of new copper(II), copper(I), and silver(I) complexes. In order to confer different solubility properties to the metal complexes and to stabilize Cu and Ag in their +1 oxidation state, the lipophilic triphenylphosphine (PPh₃) and the hydrophilic 1,3,5-triaza-7-phosphaadamantane (PTA) were selected as co-ligands in the syntheses of the Cu(I) and Ag(I) complexes. All compounds were characterized by CHN analysis, NMR, FT-IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS); the molecular structure of the copper(II) complex [Cu(L^BSPh)₂] was also determined by single-crystal X-ray diffraction. Finally, the antibacterial activity of the metal complexes, the Schiff base ligands and phosphane co-ligands, were assessed by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Gram-negative (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus).

The new 3-monosubstituted acetylacetone ligands, 3-(phenyl(1H-pyrazol-1-yl)methyl)pentane-2,4-dione (HL^acPz) and 3-((3,5-dimethyl-1H-pyrazol-1-yl)(phenyl)methyl)pentane-2,4-dione (HL^acPzMe), were synthesized and used as supporting ligands for new copper(II) and copper(I) phosphane complexes of the general formulae [Cu(HL^acX)₂(L^acX)₂] and [Cu(PPh₃)₂(HL^acX)]PF₆ (X = Pz (pyrazole) or PzMe (3,5-dimethylpyrazole)), respectively. In the syntheses of the Cu(I) complexes, the triphenylphosphine coligand (PPh₃) was used to stabilize copper in the +1 oxidation state, avoiding oxidation to Cu(II). All compounds were characterized by CHN analysis, ¹H-NMR, ¹³C-NMR, FT-IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). The ligands HL^acPz (1) and HL^acPzMe (2) and the copper complex [Cu(PPh₃)₂(HL^acPz)]PF₆ (3) were also characterized by X-ray crystallography. The reactivity of these new compounds was investigated and the new compounds 4-phenyl-4-(1H-pyrazol-1-yl)butan-2-one (7) and 4-(3,5-dimethyl-1H-pyrazol-1-yl)-4-phenylbutan-2-one (8) were obtained in basic conditions via the retro-Claisen reaction of related 3-monosubstituted acetylacetone, providing efficient access to synthetically useful ketone compounds. Compound 8 was also characterized by X-ray crystallography.