CYCLOMETALATED COMPLEXES OF PALLADIUM(II) WITH A C,N,N' TERDENTATE SCHIFF-BASE DONOR LIGAND - OXIDATIVE ADDITION OF AN ARYL-CHLORINE BOND TO PALLADIUM(0)

Treatment of 2-chlorobenzylidene)-N,N'-dimethylethylenediamine, 2-ClC6 H4C(H)=NCH2CH2NMe2, with tris(dibenzylideneacetone)dipalladium(0) in c hloroform gave the oxidative addition cyclometallated product [Pd{C6H4 C(H)=NCH2CH2NMe2}(Cl)] (1) with the palladium atom bonded to a C,N,N' terdentate donor ligand. Treatment of 1 with tertiary monophosphines g ave the cyclometallated complexes [Pd{C6H4C(H)=NCH2CH2NMe2}(Cl)(L)] (2 : L = PPh3; 3: L = PEtPh2; 4: L = PEt2Ph; 5: L = PEt3), where the phos phine 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 perchlo rate followed by reaction with tertiary monophosphines gave the cyclom etallated complexes [Pd{C6H4C(H)=N-CH2CH2NMe2}(L)][ClO4] (6: L = PPh3; 7: L = PEtPh2; 8: L = PEt2Ph; 9: L = PEt3). Reaction of 1 with thalli ium acetylacetonate gave the cyclometallated complex [Pd{C6H4C(H)=NCH2 CH2NMe2}(H3CCOCHCOCH3)]. (10). Treatment of 1 with ditertiary diphosph ines in a complex 1/diphosphine 2:1 molar ratio gave the dinuclear cyc lometallated complexes [{Pr[C6H4C(H)=NCH2CH2NMe2](Cl)}(2)(L-L)] (11: L -L = trans-Ph2PCH=CHP-Ph-2; 12: L-L = Ph2P(CH2)(3)PPh2; 13: L-L = Ph2P (CH2)(4)PPh2), where the phosphorus atom is trans to the phenyl carbon atom. Treatment of 1 with silver perchlorate followed by ditertiary d iphosphines in a complex 1/diphosphine 2:1 molar ratio gave the dinucl ear cyclometallated complexes [{Pd[C6H4C(H)=NCH2CH2NMe2]}(2)(L-L)][ClO 4](2) [14: L-L = trans-Ph2P-CH=CHPPh2; 15: L-L = Ph2P(CH2)(3)PPh2; 16: L-L = Ph2P(CH2)(4)PPh2)]. Reaction of 1 with ditertiary diphosphines in a complex molar ratio, and silver perchlorate as appropriate, gave the cyclometallated complexes 6H4C(H)=NCH2CH2PNMe2}(Ph2P(CH2)(2)PPh2-P ,P)][ClO2] (17), C6H4C(H)=NCH2CH2NMe2}(Ph2P(CH2)(3)PPh2-P,P)][ClO4] (1 8), {C6H4C(H)=NCH2CH2NMe2}(cis-Ph2PCH=CHPPh2-P,P)][Cl] (19) and {C6H4C -(H)=NCH2CH2NMe2}(Cl)(Ph2P(CH2)(4)PPh2-P,P)] (20).