Cyclometallated complexes of palladium(II) with a C, N, N′ terdentate Schiff base donor ligand. Oxidative addition of an arylchlorine bond to palladium(O)

Abstract

Treatment of N-(2-chlorobenzylidene)- N,N′-dimethylethylenediamine, 2-ClC 6H 4C(H)NCH 2CH 2NMe 2, with tris(dibenzylideneacetone)dipalladium(0) in chloroform gave the oxidative addition cyclometallated product [Pd{C 6H 4C(H)NCH 2CH 2N Me 2}(Cl)] (1) with the palladium atom bonded to a C, N, N′ terdentate donor ligand. Treatment of 1 with tertiary monophosphines gave the cyclometallated complexes [Pd{C 6H 4C(H)N CH 2CH 2NMe 2}(Cl)(L)](2: L  PPh 3; 3: L  PEtPh 2; 4: L  PEt 2Ph; 5: L  PEt 3), where the phosphine ligand is either trans to the phenyl carbon atom (2, 3) or trans to the imine nitrogen atom (4, 5). Treatment of 1 with silver perchlorate followed by reaction with tertiary monophosphines gave the cyclometallated complexes [Pd{C 6H 4C(H)NCH 2CH 2N Me 2}(L)][ClO 4] (6: L  PPh 3; 7: L  PEtPh 2; 8: L  PEt 2Ph; 9: L  PEt 3). Reaction of 1 with thallium acetylacetonate gave the cyclometallated complex [Pd{C 6H 4C(H)N CH 2CH 2NMe 2}(H 3CCOCHCOCH 3)] (10). Treatment of 1 with ditertiary diphosphines in a complex 1/diphosphine 2:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[C 6H 4C(H)N CH 2CH 2NMe 2](Cl)} 2(LL)(11: LL = trans-Ph 2PCHCHPPh 2; 12: LL  Ph 2P(CH 2) 3PPh 2;13: LL  Ph 2P(CH 2) 4PPh 2), where the phosphorus atom is trans to the phenyl carbon atom. Treatment of 1 with silver perchlorate followed by ditertiary diphosphines in a complex 1/diphosphine 2:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[C 6H 4C(H)NCH 2CH 2N Me 2]} 2 (LL)][ClO 4] 2 [14: LL= trans-Ph 2PCHCHPPh 2; 15: LL  Ph 2P(CH 2) 3PPh 2; 16: LL  Ph 2P(CH 2) 4PPh 2)]. Reaction of 1 with ditertiary diphosphines in a complex 1/diphosphine 1:1 molar ratio, and silver perchlorate as appropriate, gave the cyclometallated complexes [Pd{C 6H 4C(H)N CH 2CH 2NMe 2}(Ph 2P(CH 2) 2PPh 2- P,P)][ClO 4] (17), [Pd{C 6H 4C(H)N CH 2CH 2NMe 2}(Ph 2P(CH 2) 3PPh 2- P,P)][ClO 4] (18), [ Pd{C 6H 4C(H)N CH 2CH 2NMe 2}( cis-Ph 2PCHCHPPh 2- P,P)][Cl] (19) and [Pd{C 6H 4C-(H)NCH 2CH 2NMe 2}(Cl)(Ph 2P(CH 2) 4PPh 2- P,P)] (20).