Organopalladium and Platinum Compounds with Pentahalophenyl Ligands

Abstract

Publisher Summary This chapter discusses the existing synthetic methods that permit introduction of up to four C 6 X 5 groups in the coordination sphere of palladium or platinum as well as the reactivity of the different complexes obtained. It presents much more numerous compounds with the metals in oxidation state (II), because these provide the gateway for the preparation of other complexes involving oxidation state (I), (III), or (IV), whose chemistry is more reduced in scope. All the complexes show infrared bands characteristic of the presence of the C 6 X 5 groups, most readily observed for C 6 F 5 compounds. Some of these internal absorptions are related to the skeletal symmetry of the molecule and to the oxidation state of the metal center and have therefore been used for structural diagnosis. The information obtained from infrared (IR) data is also discussed. Because the carbanions C 6 X 15 – are not strong nucleophiles, they do not displace neutral Group Vb ligands in the starting compounds MCI 2 L 2 , and bisaryl derivatives M(C 6 X 5 ) 2 L 2 are obtained. A general method that gives the four possible complexes in yields over 85% involves the addition of aqueous HCI to the corresponding tetrakis(pentahalophenyl) compound in methanolic solution (2:1 ratio) albeit half of the pentahalophenyl groups are lost as C 6 X 5 H. The title compounds have interesting possibilities for a variety of syntheses. Platinum(II) complexes cis-Pt(C 6 X 5 ) 2 L 2 undergo redox condensation with Pt(η-C 2 H 4 )(PPh 3 ) 2 in oxygen-free refluxing tetrahydrofuran to give binuclear Pt(I) complexes. The C 5 F 5 groups show strong absorptions in the 1650, 1500, 1300, 1050, 950, and 800 cm –1 regions.