New developments in the studies of the reactivity of cyclometallated palladium(II) compounds with homo- ([P,P],[As,As]) and heterobidentate ([P,N],[P,O]) ligands

Treatment of the chloro-bridged dinuclear compounds [{Pd[RC6H3C(H)double bond; length as m-dashNCy-C2,N]}(μ-Cl)]2 (R = 4-(COH), 1; R = 5-(COH), 2) with bidentate phosphorus or arsenic diphosphines or diarsine ligands in 1:1 molar ratio gave the dinuclear complexes [{Pd[RC6H3C(H)double bond; length as m-dashNCy-C2,N](Cl)}2{μ-(o-Tol)2P(CH2)2P(o-Tol)2}] (R = 4-(COH), 3; R = 5-(COH), 4), [{Pd[RC6H3C(H)double bond; length as m-dashNCy-C2,N](Cl)}2{μ-Ph2PC4H2(NH)CH2PPh2}] (R = 4-(COH), 5; R = 5-(COH), 6) and [{Pd[RC6H3C(H)double bond; length as m-dashNCy-C2,N](Cl)}2{μ-Ph2As(CH2)2AsPh2}] (R = 4-(COH), 7; R = 5-(COH), 8) with the homobidentate [P,P] and [As,As] ligands in a bridging mode. Treatment of 1 and 2 with the aminophosphine Ph2P(CH2)2NH2 yields the dinuclear complexes [{Pd[RC6H3C(H)double bond; length as m-dashNCy-C2,N](Cl)}2{μ-Ph2P(CH2)2NH2}] (R = 4-(COH), 9; R = 5-(COH), 10). The analogous reactions carried out in a 1:2 molar ratio, in the presence of NH4PF6 or NaClO4, gave the mononuclear compounds [Pd{RC6H3C(H)double bond; length as m-dashNCy-C2,N}{(o-Tol)2P(CH2)2P(o-Tol)2-P,P}][PF6] (R = 4-(COH), 11; R = 5-(COH), 12), [Pd{RC6H3C(H)double bond; length as m-dashNCy-C2,N}{Ph2PC4H2(NH)CH2PPh2-P,P}][ClO4] (R = 4-(COH), 13; R = 5-(COH), 14) and [Pd{RC6H3C(H)double bond; length as m-dashNCy-C2,N}{Ph2As(CH2)2AsPh2-As,As}][ClO4](R = 4-(COH), 15; R = 5-(COH), 16), with the [P,P] and [As,As] ligands chelated to the palladium atom. Treatment of 2 with Ph2P(CH2)3NH2 in a 1:2 molar ratio in acetone in the presence of NH4PF6 afforded the mononuclear compound [Pd{5-(COH)C6H3C(H)double bond; length as m-dashNCy-C2,N}{Ph2P(CH2)3N(double bond; length as m-dashMe2)-P,N}][PF6], 17, via intermolecular condensation between the aminophosphine and the solvent. Condensation was precluded using toluene as solvent to give [Pd{RC6H3C(H)double bond; length as m-dashNCy-C2,N}{Ph2P(CH2)nNH2-P,N}][PF6], (n = 3, R = 5-(COH), 18; n = 2, R = 4-(COH), 19; n = 2, R = 5-(COH), 20). Treatment of 1 and 2 with Ph2P(C6H4)CHO in a 1:2 molar ratio in the presence of NH4PF6 gave the mononuclear complexes [Pd{RC6H3C(H)double bond; length as m-dashNCy-C2,N}{2-(Ph2P)C6H4CHO-P,O}][PF6] (R = 4-(COH), 21; R = 5-(COH), 22) with the palladium atom bonded to four different atoms (C, N, P, O) and a chelating [P,O] ligand. The crystal structures of compounds 7, 11, 15 and 21 have been determined by X-ray crystallography.