Abstract
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(PPh(3))(2)(HL(acX))]PF(6) (X = Pz (pyrazole) or PzMe (3,5-dimethylpyrazole)), respectively. In the syntheses of the Cu(I) complexes, the triphenylphosphine coligand (PPh(3)) was used to stabilize copper in the +1 oxidation state, avoiding oxidation to Cu(II). All compounds were characterized by CHN analysis, (1)H-NMR, (13)C-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(PPh(3))(2)(HL(acPz))]PF(6) (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.