New thiosemicarbazone palladacycles with chelating bis(diphenylphosphino)methane

Treatment of the thiosemicarbazones 2-ClC6H4C(Me){double bond, long}NN(H)C({double bond, long}S)NHR, (R: Me, a; Et, b) and 2-BrC6H4C(Me){double bond, long}NN(H)C({double bond, long}S)NHR (R: Me, c; Et, d) with lithium tetrachloropalladate(II) in methanol or palladium(II) acetate in acetic acid gave the tetranuclear cyclometallated complexes [Pd{2-XC6H3C(Me){double bond, long}NN{double bond, long}C(S)NHR}]4 (X/R: Cl/Me, 1a; Cl/Et, 1b; Br/Me, 1c; Br/Et, 1d). Reaction of 1a-1d with bis(diphenylphosphino)methane, Ph2PCH2PPh2, in a 1:4 molar ratio and concentrated hydrochloric acid gave the mononuclear complexes [Pd{2-XC6H3C(Me){double bond, long}NN(H)-C({double bond, long}S)NHR}(Ph2PCH2PPh2-P,P)](Cl) (2a-2d). Reaction of 1a-1d with bis(diphenylphosphino)methane, Ph2PCH2PPh2, in 1:2 and 1:4 molar ratios gave the dinuclear or mononuclear complexes [{Pd[2-XC6H3C(Me){double bond, long}NN{double bond, long}C(S)NHR]}2(μ-Ph2PCH2PPh2)] (3a-3d), and [Pd{2-XC6H3C(Me){double bond, long}NN{double bond, long}C(S)NHR}(Ph2PCH2PPh2-P)] (4a-4d), with bridging and chelating diphosphine, respectively. The molecular structures of complexes 1b, 1d, 4c and 4d have been determined by X-ray diffraction analysis. © 2006 Elsevier Ltd. All rights reserved.