Synthesis and characterization of silver(I) derivatives containing acylpyrazolonate and phosphino ligands: X-ray crystal structures of monomeric [Ag(QnPe)(PPh3)2] and of dimeric [{Ag(QnPe)(PiBu3)}2] (QnPe = 1-phenyl-3-methyl-4-tert-butylacetylpyrazolon-5-

New silver(I) acylpyrazolonate derivatives [Ag(Q)], [Ag(Q)(PR3)]2 and [Ag(Q)(PR3)2] (HQ = 1-R1-3-methyl-4-R2(Cdouble bond; length as m-dashO)pyrazol-5-one, HQBn = R1 = C6H5, R2 = CH2C6H5; HQCHPh2 = R1 = C6H5, R2 = CH(C6H5)2; HQnPe = R1 = C6H5, R2 = CH2C(CH3)3; HQtBu = R1 = C6H5, R2 = C(CH3)3; HQfMe = R1 = C6H4-p-CF3, R2 = CF3; HQfEt = R1 = C6H5, R2 = CF2CF3; R = Ph or iBu) have been synthesized and characterized in the solid state and solution. The crystal structure of 1-(4-trifluoromethylphenyl)-3-methyl-5-pyrazolone, the precursor of proligand HQfMe and of derivatives [Ag(QnPe)(PPh3)2] and [Ag(QnPe)(PiBu3)]2 have been investigated. [Ag(QnPe)(PPh3)2] is a mononuclear compound with a silver atom in a tetrahedrally distorted AgO2P2 environment, whereas [Ag(QnPe)(PiBu3)]2 is a dinuclear compound with two O2N-exotridentate bridging acylpyrazolonate ligands connecting both silver atoms, their coordination environment being completed by a phosphine ligand.