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-FC 6 H 4 C(Me) NN(H)C( S)NHME a , 4-FC 6 H 4 C(Me) NN(H)C( S)NHEt b , and 2-BrC 6 H 4 C(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-FC 6 H 3 C(Me) NN C(S)NHMe}] 4 1a , [Pd{4-FC 6 H 3 C(Me) NN C-(S)NHEt}] 4 1b , and [Pd{2-BrC 6 H 3 C(Me) NN C(S)NHPh}] 4 1c . Reaction of 1a – c with the diphosphines Ph 2 P(CH 2 ) n PPh 2 dppm ( n  = 1), dppe ( n  = 2), dppp ( n  = 3), dppb ( n  = 4) or Ph 2 PCH CHPPh 2 trans -dppe, in a 1:2 molar ratio gave the dinuclear phosphine-bridged complexes [(Pd{XC 6 H 3 C(Me) NN C(S)NHR}) 2 (μ-Ph 2 P(CH 2 ) n PPh 2 )] 2a – c , 3a – c , 4a – c , 5a – c ( n  = 1–4) and [(Pd{XC 6 H 3 C(Me) NN C(S)NHR}) 2 (μ-Ph 2 PCH CH-PPh 2 )] 6a – c . Treatment of 1a – c with PPh 2 CH 2 PPh 2 , dppm, in a 1:4 molar ratio gave the mononuclear cyclometallated complexes [Pd{XC 6 H 3 C(Me) NN C(S)NHR}-(Ph 2 PCH 2 PPh 2 -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.