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

Abstract

Treatment of the chloro-bridged dinuclear compounds [{Pd[RC 6H 3C(H) NCy- 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[RC 6H 3C(H) NCy- C2, N](Cl)} 2{μ-( o-Tol) 2P(CH 2) 2P( o-Tol) 2}] (R = 4-(COH), 3; R = 5-(COH), 4), [{Pd[RC 6H 3C(H) NCy- C2, N](Cl)} 2{μ-Ph 2PC 4H 2(NH)CH 2PPh 2}] (R = 4-(COH), 5; R = 5-(COH), 6) and [{Pd[RC 6H 3C(H) NCy- C2, N](Cl)} 2{μ-Ph 2As(CH 2) 2AsPh 2}] (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 Ph 2P(CH 2) 2NH 2 yields the dinuclear complexes [{Pd[RC 6H 3C(H) NCy- C2, N](Cl)} 2{μ-Ph 2P(CH 2) 2NH 2}] (R = 4-(COH), 9; R = 5-(COH), 10). The analogous reactions carried out in a 1:2 molar ratio, in the presence of NH 4PF 6 or NaClO 4, gave the mononuclear compounds [Pd{RC 6H 3C(H) NCy- C2, N}{( o-Tol) 2P(CH 2) 2P( o-Tol) 2- P, P}][PF 6] (R = 4-(COH), 11; R = 5-(COH), 12), [Pd{RC 6H 3C(H) NCy- C2, N}{Ph 2PC 4H 2(NH)CH 2PPh 2- P, P}][ClO 4] (R = 4-(COH), 13; R = 5-(COH), 14) and [Pd{RC 6H 3C(H) NCy- C2, N}{Ph 2As(CH 2) 2AsPh 2- As,As}][ClO 4](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 Ph 2P(CH 2) 3NH 2 in a 1:2 molar ratio in acetone in the presence of NH 4PF 6 afforded the mononuclear compound [Pd{5-(COH)C 6H 3C(H) NCy- C2, N}{Ph 2P(CH 2) 3N( Me 2)- P, N}][PF 6], 17, via intermolecular condensation between the aminophosphine and the solvent. Condensation was precluded using toluene as solvent to give [Pd{RC 6H 3C(H) NCy- C2, N}{Ph 2P(CH 2) nNH 2- P, N}][PF 6], ( n = 3, R = 5-(COH), 18; n = 2, R = 4-(COH), 19; n = 2, R = 5-(COH), 20). Treatment of 1 and 2 with Ph 2P(C 6H 4)CHO in a 1:2 molar ratio in the presence of NH 4PF 6 gave the mononuclear complexes [Pd{RC 6H 3C(H) NCy- C2, N}{2-(Ph 2P)C 6H 4CHO- P, O}][PF 6] (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.