Synthesis and structural characterization of tridentate [C,N,S] thiosemicarbazone palladacycles. Crystal and molecular structures of [Pd{3-FC 6H 3C(Me) [dbnd]NN [dbnd]C(S)NHMe}] 4, [Pd{4-FC 6H 3C(Me) [dbnd]NN [dbnd]C(S)NHEt}] 4 and [(Pd{2-BrC 6H 3C(Me) [dbnd]NN [dbnd]C(S)NHPh}) 2(μ-Ph 2P(CH 2) 2PPh 2)

Abstract

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