New palladium(II) cyclometallated compounds derived from trans-cinnamalylideneimines via CH activation of an sp2-aliphatic carbon atom

Treatment of the Schiff-base ligands C 6 H 5 C(H)=C(R)C(H)=NCy (R=H, a; R=Me, b) with Pd(OAc) 2 gave the acetato-bridged dinuclear compounds [Pd{C 6 H 5 C=C(R)C(H)=NCy}(O 2 CMe)] 2 (R=H, 1a; R=Me, 1b) after C-H activation of the aliphatic carbon atom. Reaction of 1a and 1b with aqueous sodium chloride gave the dinuclear chloro-bridged compounds [Pd{C 6 H 5 C=C(R)C(H)=NCy}(X)] 2 (R=H, 2a; R=Me, 2b), which could also be prepared by treatment of the ligands with Li 2 [PdCl 4 ] in methanol. Reaction of 1a with aqueous sodium bromide or iodide gave the halide-bridged species [Pd{C 6 H 5 C=C(H)C(H)=NCy}(X)] 2 (X=Br, 3a; X=I, 4a). Treatment of 1a and 1b with Tl(acac), Tl(C 5 H 5 ) or PPh 3 , as appropriate, gave the mononuclear complexes [Pd{C 6 H 5 C=C(R)C(H)=NCy}(acac)], (R=H, 5a; R=Me, 3b) [Pd{C 6 H 5 C=C(H)C(Me)=NCy}(C 5 H 5 )] (4b) and [Pd{C 6 H 5 C=C(H)C(Me)=NCy}(PPh 3 )] (5b). © 2002 Elsevier Science B.V. All rights reserved.