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

Treatment of 4-MeOC 6 H 4 C(Me)═NN(H)C(═S)NHMe ( 1 ), with potassium tetrachloropalladate gave the tetranuclear compound [Pd{4-MeOC 6 H 3 C(Me)═NN═C(S)NHMe}] 4 ( 2 ), with the ligand as terdendate [ C, N, S ]. Reaction of 2 with the diphosphines Ph 2 PCH 2 PPh 2 (dppm), Ph 2 PC(═CH 2 )PPh 2 (vdpp), and Ph 2 PC(CH 2 ) 2 PPh 2 (dpcp) gave the mononuclear complexes [Pd{4-MeOC 6 H 3 C(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 self-organization leading to chains and/or layers in the molecular array.