Synthesis and structural characterization of tridentate [C,N,S] thiosemicarbazone palladacycles. Crystal and molecular structures of [Pd{3-FC6H3C(Me)NNC(S)NHMe}]4, [Pd{4-FC6H3C(Me)NNC(S)NHEt}]4 and [(Pd{2-BrC6H3C(Me)NNC(S)NHPh})2(μ-Ph2P(CH2)2PPh2)]

Reaction of the thiosemicarbazones 3-FC6H4C(Me)NN(H)C(S)NHME a, 4-FC6H4C(Me)NN(H)C(S)NHEt b, and 2-BrC6H4C(Me)NN(H)C(S)NHPh c, with potassium tetrachloropalladate(II) in ethanol, lithium tetrachloropalladate(II) in methanol or palladium(II) acetate in acetic acid gave the tetranuclear cyclometallated complexes [Pd{3-FC6H3C(Me)NNC(S)NHMe}]41a, [Pd{4-FC6H3C(Me)NNC-(S)NHEt}]41b, and [Pd{2-BrC6H3C(Me)NNC(S)NHPh}]41c. Reaction of 1a–c with the diphosphines Ph2P(CH2)nPPh2 dppm (n = 1), dppe (n = 2), dppp (n = 3), dppb (n = 4) or Ph2PCHCHPPh2trans-dppe, in a 1:2 molar ratio gave the dinuclear phosphine-bridged complexes [(Pd{XC6H3C(Me)NNC(S)NHR})2(μ-Ph2P(CH2)nPPh2)] 2a–c, 3a–c, 4a–c, 5a–c (n = 1–4) and [(Pd{XC6H3C(Me)NNC(S)NHR})2(μ-Ph2PCHCH-PPh2)] 6a–c. Treatment of 1a–c with PPh2CH2PPh2, dppm, in a 1:4 molar ratio gave the mononuclear cyclometallated complexes [Pd{XC6H3C(Me)NNC(S)NHR}-(Ph2PCH2PPh2-P)] 7a–c; however, the diphosphines with n ⩾ 2 failed to give the analogous reaction. The molecular structures of 1a, 1b and 3c have been determined by X-ray diffraction analysis and the intra- and intermolecular interactions are discussed.

The preparation and characterization of tetranuclear and dinuclear thiosemicarbazone palladium(II) complexes have been carried out. The crystal structure analysis for 1a and 1b shows intra- and intermolecular interactions, which in the former case lead to formation of chains along the bisector of the a/b axes, as well as along the b axis.Figure optionsDownload as PowerPoint slide