Palladium(II) complexes of pyrazolate ligands with thioether chelate arms

Abstract

Two 3,5-disubstituted pyrazole derivatives with one (HL1) or two (HL2) thioether functions per side arm have been used as ligands towards Ag-I and Pd-II ions. Both form the metallamacrocylic complexes AgL1/2 (1, 3) with a common Ag(mu-pz) core. In the presence of excess Ag-I in acetone solution, 3 converts into hexametallic Ag-6(L-2)(2)(acetone)(6)(4) (4). Upon treatment with Pd(MeCN)(4)(2), both 1 and 3 readily undergo transmetallation to dinuclear complexes with the general formula Pd2L2(2) (2, 5) having a favorable bis(pyrazolato)-bridged {Pd2N4S4} core structure and dangling thioether arms. Complexes 2, 4, and 5 have been structurally authenticated by X-ray diffraction. ESI mass spectrometry and NMR spectroscopy have revealed that the complexes largely retain their integrity in MeCN solutions.