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)(2)PPh-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)=N N(H)C(=O)NH2}(Cl)] (c) with tertiary monophosphine ligands in a complex-pho sphine 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 per chlorate, 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-Me2C6H 2C(Me)=NN(H)C(=O)NH2}(L)][ClO4] (5c-8c). Reaction of a, b and c with tertia ry monophosphines in a complex-phosphine 1:2 ratio gave the C only bonded n on-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-Me2C6H 2C(Me)=NN(H)C(=O)NH2}(PEt2Ph)(2)(Cl)] (9c). Treatment of a, b and c with th e triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine (trifos) yielde d 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)(2)PPh ). The complexes were characterised by their elemental analysis (C, H, N) a nd by IR and P-31-{H-1} and H-1-NMR spectroscopy. [Pd{C6H4C(Et)=NN(H)C(=O)N H2}(PPh3)][ClO4] (5b) and [Pd{C6H4C(Et)=NN(H)C(=O)NH2}{(Ph2PCH2CH2)(2)PPh-P ,P,P}][Cl] (10b) were characterised crystallographically. (C) 2000 Elsevier Science S.A. All rights reserved.