文摘
Insertion of CO into the Pd−Caryl bond of complexes [PdI{C6H4{NHC(Me)CHC(O)Me}-2}(NN)] afforded the benzoyl derivatives [PdI{C(O)C6H4{NHC(Me)CHC(O)Me}-2}(NN)] [NN = 4,4′-di-tert-butyl-2,2′-dipyridyl (tBubpy) (1a), N,N,N′,N′-tetramethylethylenediamine (tmeda) (1b)]. The reactions of [Pd{C,C-C6H4{NH═C(Me)CHC(O)Me}-2}(tmeda)]OTf (OTf = CF3SO3) with excess CO and tmeda (2:1) or HOTf (1:1) produced the dinuclear benzoyl complex [{Pd{C,N,O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}2(μ-tmeda)] (2) or [Pd2{μ-O,C,N,O′-{O═CC6H4{NC(Me)CHC(O)Me}-2}2}] (3), respectively. The latter reacted with anionic or neutral ligands to give complexes Bu4N[{Pd{C,N,O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}2(μ-OH)] (4), Q[Pd{C,N,O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}}Cl] [Q = PPN (5a), NMe4 (5b)], or [{Pd{C,N,O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}L] (L = CNtBu (6a), CNXy (6b), PPh3 (6c), NH3 (6d), NH2Me (6e), MeCN (6f), dmso (6g)), respectively. The reaction of dimethylacetylenedicarboxylate (DMAD) with [PdI{C6H4{NHC(Me)CHC(O)Me}-2}(tmeda)] (1:1) afforded [PdI{C6H4{NHC(Me)C{Z-C(CO2Me)═CH(CO2Me)}C(O)Me}}-2}(tmeda)] (7Z), resulting from the insertion of the alkyne into the C(sp2)−H bond of the enaminone substituent. 7Z isomerized into the E analogue (7E) when heated in toluene at 95 °C and reacted in two steps with AgClO4 and XyNC (1:1:2) to give the C,N,O-pincer derivative Pd{C,N,O-{C(═NXy)C6H4{NC(Me)C{C(CO2Me)═CHCO2Me)}C(O)Me}-2}(CNXy)] (8) as a mixture of the Z and E isomers. The latter complex converted, after a photochemical oxygenation, into the palladacycle [Pd{C,N,O-{C(═NXy)C6H4{N(dmoc)}-2](CNXy)]·2CHCl3 (9), where the imino substituent dmoc is the cycle 1,2-di(methoxycarbonyl)-3-oxocyclopent-1-ene-4-yl. Compound 8 or 9 reacted with triflic or picric acid to give the species Pd{C,N,O-{C(═NHXy)C6H4{NC(Me)C{C(CO2Me)═CHCO2Me)}C(O)Me}-2}(CNXy)]OTf (10) or [Pd{C,N,O-{C(═NXy)C6H4{N(dmoc)}-2](CNXy)]·Hpic (11; Hpic = picric acid), respectively. The crystal structures of complexes 2, 3, 5a, 6b, 6c, 6e, 7Z, 7E, and 10 have been determined.