Reactivity of cyclometallated semicarbazone complexes of Pd(II): crystal and molecular structures of [Pd{C6H4C(Et)NN(H)C(O)NH2}(PPh3)][ClO4] and [Pd{C6H4C(Et)NN(H)C(O)NH2}{(Ph2PCH2CH2)2PPh-P,P,P}][Cl]

Treatment of the cyclometallated complexes [Pd{4-MeC6H3C(Me)NN(H)C(O)NH2}(Cl)] (a), [Pd{C6H4C(Et)NN(H)C(O)NH2}(Cl)] (b) and [Pd{3,4-Me2C6H2C(Me)NN(H)C(O)NH2}(Cl)] (c) with tertiary monophosphine ligands in a complex–phosphine 1:1 molar ratio yielded [C, N] bonded cyclometallated complexes [Pd{4-MeC6H3C(Me)NN(H)C(O)NH2}(Cl)(L)] (1a–4a), [Pd{C6H4C(Et)NN(H)C(O)NH2}(Cl)(L)] (1b–4b) and [Pd{3,4-Me2C6H2C(Me)NN(H)C(O)NH2}(Cl)(L)] (1c–4c), [L=PPh3, PMePh2, PEtPh2 and PEt2Ph]. 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-MeC6H3C(Me)NN(H)C(O)NH2}(L)][ClO4] (5a–8a), [Pd{C6H4C(Et)NN(H)C(O)NH2}(L)][ClO4] (5b–8b) and [Pd{3,4-Me2C6H2C(Me)NN(H)C(O)NH2}(L)][ClO4] (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-MeC6H3C(Me)NN(H)C(O)NH2}(PEt2Ph)2(Cl)] (9a), [Pd{C6H4C(Et)NN(H)C(O)NH2}(PPh3)2(Cl)] (9b) and [Pd{3,4-Me2C6H2C(Me)NN(H)C(O)NH2}(PEt2Ph)2(Cl)] (9c). Treatment of a, b and c with the triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine (trifos) yielded the non-cyclometallated complexes [Pd{4-[MeC6H3C(Me)NN(H)C(O)NH2}{L-P,P,P}][Cl] (10a), [Pd{C6H4C(Et)NN(H)C(O)NH2}{L-P,P,P}][Cl] (10b) and [Pd{3,4-Me2C6H2C(Me)NN(H)C(O)NH2}{L-P,P,P}][Cl] (10c) (L=(Ph2PCH2CH2)2PPh). The complexes were characterised by their elemental analysis (C, H, N) and by IR and 31P-{1H} and 1H-NMR spectroscopy. [Pd{C6H4C(Et)NN(H)C(O)NH2}(PPh3)][ClO4] (5b) and [Pd{C6H4C(Et)NN(H)C(O)NH2}{(Ph2PCH2CH2)2PPh-P,P,P}][Cl] (10b) were characterised crystallographically.