Reactivity of cyclometallated palladium(II) compounds derived from N-(benzylidene)xylylendiamines

Abstract

The reaction of [1,3-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](μ-O 2CMe)} 2C 6H 4] ( 1), with triphenylphosphine in a 1:2 molar ratio gave the doubly cyclometallated complex [1,3-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](OAc)(PPh 3)} 2C 6H 4] ( 3), after cleavage of the two acetate-bridges. Treatment of the chloro-bridged complexes [1,3-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](μ-Cl)} 2C 6H 4] 2 ( 2) and [1,4-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](μ-Cl)} 2C 6H 4] 2 ( 8) with the tertiary monophosphines PPh 3, P( p-MeOC 6H 4) 3 and P( p-NMe 2C 6H 4)Ph 2 gave the doubly cyclometallated complexes [1,3-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](Cl)(PR 3)} 2C 6H 4] (PR 3=PPh 3, 4; P( p-MeOC 6H 4) 3, 5; P( p-NMe 2C 6H 4)Ph 2, 6) and [1,4-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](Cl)(PR 3)} 2C 6H 4] (PR 3=PPh 3, 9; P( p-MeOC 6H 4) 3, 10; P( p-NMe 2C 6H 4)Ph 2, 11). Reaction of complex 4 with PPh 3 did not yield the expected non-cyclometallated complex. Reaction of complexes 2 and 8 with the tertiary diphosphine cis-Ph 2PCHCHPPh 2, in a 1:4 molar ratio and NaClO 4, yielded the doubly cyclometallated complexes [1,3-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](Ph 2PCHCHPPh 2- P, P)} 2C 6H 4][ClO 4] 2 ( 7) and [1,4-{Pd[2,3,4-(MeO) 3C 6HC(H)NCH 2](Ph 2PCHCHPPh 2- P, P)} 2C 6H 4][ClO 4] 2 ( 12), respectively, with the diphosphine as a chelating bidentate ligand.