Synthesis and Structural Characterization of Palladium and Platinum Bimetallic Compounds Derived From Bidentate P,S-Palladacycle Metaloligands

Treatment of 4-MeOC6H4C(Me)═NN(H)C(═S)NHMe (1), with potassium tetrachloropalladate gave the tetranuclear compound [Pd{4-MeOC6H3C(Me)═NN═C(S)NHMe}]4 (2), with the ligand as terdendate [C,N,S]. Reaction of 2 with the diphosphines Ph2PCH2PPh2 (dppm), Ph2PC(═CH2)PPh2 (vdpp), and Ph2PC(CH2)2PPh2 (dpcp) gave the mononuclear complexes [Pd{4-MeOC6H3C(Me)═NN═C(S)NHMe}(L)] (L = dppm-P, 3; dpcp-P, 4; vdpp-P, 5) with the diphosphine ligand binding in a monodentate fashion. Compounds 3−5 may bond systematically to a second metal atom, palladium or platinum, through the noncoordinated phosphorus atom and the sulfur atom of the thiosemicarbazone moiety to give the dinuclear compounds 6−10, thus behaving as bidentate P,S-palladacycle metaloligands. All the compounds have been characterized by elemental analysis, and by IR and NMR spectroscopy; and the crystal and molecular structures of 1, 2, 6−10 have been determined by X-ray crystallography. Inter- and intramolecular hydrogen bonding in the solid results in crystal se...