Polynuclear cyclometallated palladium (II) complexes derived from potentially hexadentate Schiff base ligands. Crystal structures of [(Cl)Pd{Me 2NCH 2CH 2N(H)C}C 6H 2{C(H)NCH 2CH 2NMe 2}Pd(Cl)] and [{(Ph 2PCH 2CH 2) 2PPh- P, P, P}Pd{Me 2NCH 2CH 2N(H)C}C 6H 2{C(H)NCH 2CH 2NMe 2}Pd{(Ph 2PCH 2CH 2) 2PPh- P, P, P}][Cl] 2

Abstract

The oxidative addition reaction of 1,4-(CN(H)CH 2CH 2Me 2) 2-2,5-Cl 2C 6H 2 with tris(dibenzylideneacetone)dipalladium(0) in benzene gave the doubly cyclometallated compound [(Cl)Pd{Me 2NCH 2CH 2N(H)C}C 6H 2{C(H)NCH 2CH 2NMe 2}Pd(Cl)] ( 1) with each palladium atom C, N, N′ bonded to the ligand. Treatment of 1 with thallium acetylacetonate gave the dinuclear cyclometallated complex 2 with two chelating acetylacetonate ligands. Reaction of 1 with tertiary monophosphines in a 1–phosphine 1:2 molar ratio gave dinuclear cyclometallated complexes 3– 7, in which the palladiumNMe 2 bond has been broken, whereas treatment of 1 with silver perchlorate, followed by reaction with PPh 3 in a 1–phosphine 1:2 molar ratio gave cyclometallated complex 4 where the ligand remains C, N, N′ bonded and the chloride ligand has been substituted by triphenylphosphine. Treatment of 1 with tertiary diphosphines leads to dinuclear compounds 8, 10 and 11, whilst previous treatment of 1 with silver perchlorate followed by the diphosphine 1,4-bis(diphenylphosphino)butane (dppb) in a 1–diphosphine 1:1 molar ratio yielded the tetranuclear complex 9. Reaction of 1 with the tertiary triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine in 1:2 molar ratio gave the complex [{(Ph 2PCH 2CH 2) 2PPh- P, P, P}Pd{Me 2NCH 2CH 2N(H)C}-C 6H 2{C(H)NCH 2CH 2NMe 2}Pd{(Ph 2PCH 2CH 2) 2PPh- P, P, P}][Cl] 2 ( 12) in which both palladium atoms are pentacoordinated. The crystal structures of 1 and 12 are described.