Reactivity of cyclometallated semicarbazone complexes of Pd(II): crystal and molecular structures of [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}(PPh 3)][ClO 4] and [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}{(Ph 2PCH 2CH 2) 2PPh- P, P, P}][Cl

Abstract

Treatment of the cyclometallated complexes [Pd{4-MeC 6H 3C(Me)NN(H)C(O)NH 2}(Cl)] ( a), [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}(Cl)] ( b) and [Pd{3,4-Me 2C 6H 2C(Me)NN(H)C(O)NH 2}(Cl)] ( c) with tertiary monophosphine ligands in a complex–phosphine 1:1 molar ratio yielded [C, N] bonded cyclometallated complexes [Pd{4-MeC 6H 3C(Me)NN(H)C(O)NH 2}(Cl)(L)] ( 1a– 4a), [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}(Cl)(L)] ( 1b– 4b) and [Pd{3,4-Me 2C 6H 2C(Me)NN(H)C(O)NH 2}(Cl)(L)] ( 1c– 4c), [L=PPh 3, PMePh 2, PEtPh 2 and PEt 2Ph]. Reaction of a, b and c with silver perchlorate, prior to the treatment with the monophosphine gave the [C, N, O] bonded cyclometallated complexes [Pd{4-MeC 6H 3C(Me)NN(H)C(O)NH 2}(L)][ClO 4] ( 5a– 8a), [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}(L)][ClO 4] ( 5b– 8b) and [Pd{3,4-Me 2C 6H 2C(Me)NN(H)C(O)NH 2}(L)][ClO 4] ( 5c– 8c). Reaction of a, b and c with tertiary monophosphines in a complex–phosphine 1:2 ratio gave the C only bonded non-cyclometallated complexes [Pd{4-MeC 6H 3C(Me)NN(H)C(O)NH 2}(PEt 2Ph) 2(Cl)] ( 9a), [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}(PPh 3) 2(Cl)] ( 9b) and [Pd{3,4-Me 2C 6H 2C(Me)NN(H)C(O)NH 2}(PEt 2Ph) 2(Cl)] ( 9c). Treatment of a, b and c with the triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine (trifos) yielded the non-cyclometallated complexes [Pd{4-[MeC 6H 3C(Me)NN(H)C(O)NH 2}{L- P, P, P}][Cl] ( 10a), [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}{L- P, P, P}][Cl] ( 10b) and [Pd{3,4-Me 2C 6H 2C(Me)NN(H)C(O)NH 2}{L- P, P, P}][Cl] ( 10c) (L=(Ph 2PCH 2CH 2) 2PPh). The complexes were characterised by their elemental analysis (C, H, N) and by IR and 31P-{ 1H} and 1H-NMR spectroscopy. [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}(PPh 3)][ClO 4] ( 5b) and [Pd{C 6H 4C(Et)NN(H)C(O)NH 2}{(Ph 2PCH 2CH 2) 2PPh- P, P, P}][Cl] ( 10b) were characterised crystallographically.