Copper(I) monophosphine complexes with functionalized acylpyrazolonate ligands: Syntheses of heterobimetallic Cu–Zn and Cu–Ru adducts

Copper(I) acylpyrazolonate derivatives of formula [Cu(Q)(PPh3)2] (HQ = HQC2F5 =  1-phenyl-3-methyl-4-pentafluoropropanoylpyrazol-5-one, HQCF3,CF3 = 1-(4-trifluoromethyl)phenyl-3-methyl-4-trifluoroacetylpyrazol-5-one, HQnaph = 1-phenyl-3-methyl-4-(1-naphthoyl)pyrazol-5-one, HQfur = 1-phenyl-3-methyl-4-furylpyrazol-5-one, HQthi = 1-phenyl-3-methyl-4-thienoylpyrazol-5-one, HQCF3,py = 1-(2-pyridyl)-3-methyl-4-trifluoromethylpyrazol-5-one) have been synthesized and characterized, both in the solid state and in solution. The isomorphous crystal structures of [Cu(Qfur)(PPh3)2] and [Cu(Qthi)(PPh3)2] and of [Cu(QC2F5)(PPh3)2] show their copper atoms in distorted tetrahedral environments. Apart from the derivative [Cu(Qnaph)(PPh3)2], they are fluxional in chloroform solution, dissociating partially to the [Cu(Q)(PR3)] fragment and free PR3, or existing in solution as [Cu(O2–Q)(PR3)2] or [Cu(O–Q)(PR3)2] species, with CuO2P2 or CuOP2 metal environments, in equilibrium with each other. By contrast, in [Cu(QCF3,py)(PPh3)2] the QCF3,py ligand is coordinated to copper through the nitrogen atoms of the pyrazole and pyridine rings. The latter compound reacts with Zn(BF4)2 · xH2O and [Ru(p-cymene)Cl2]2 affording ionic heterobimetallic adducts.

Graphical abstractNew phosphino–copper(I) acylpyrazolonate derivatives have been synthesized and characterized in the solid state and solution. They are monomeric compounds where the acylpyrazolonates act as O2- or N2-donor ligands depending on their substituents. In the latter case, the ligand is also able to coordinate other metal centres through the carbonyl arms, affording heterobimetallic derivatives.Figure optionsDownload full-size imageDownload as PowerPoint slide