Complexes [Pd{C,N-Ar{C(Me)=NOH}-2}(μ-Cl)](2) (1) with Ar = C(6)H(4), C(6)H(3)NO(2)-5 or C(6)H(OMe)(3)-4,5,6, were obtained from the appropriate oxime, Li(2)[PdCl(4)] and NaOAc. They reacted with neutral monodentate C-, P- or N-donor ligands (L), with [PPN]Cl ([PPN] = Ph(3)P=N=PPh(3)), with Tl(acac) (acacH = acetylacetone), or with neutral bidentate ligands N^N (tetramethylethylenediamine (tmeda), 4,4'-di-tert-butyl-2,2'-bipyridine ((t)Bubpy)) in the presence of AgOTf or AgClO(4) to afford complexes of the types [Pd{C,N-Ar{C(Me)=NOH}-2}Cl(L)] (2), [PPN][Pd{C,N-Ar{C(Me)=NOH}-2}Cl(2)] (3), [Pd{C,N-Ar{C(Me)=NOH}-2}(acac)] (4) or [Pd{C,N-Ar{C(Me)=NOH}-2}(N^N)]X (X = OTf, ClO(4)) (5), respectively. Complexes 1 reacted with bidentate N^N ligands in the presence of a base to afford mononuclear zwitterionic oximato complexes [Pd{C,N-Ar{C(Me)=NO}-2}(N^N)] (6). Dehydrochlorination of complexes 2 by a base yielded dimeric oximato complexes of the type [Pd{μ-C,N,O-Ar{C(Me)[double bond, length as m-dash]NO}-2}L](2) (7). The insertion of XyNC into the Pd-C(aryl) bond of complex 2 produced the mononuclear iminoaryloxime derivative [Pd{C,N-C(=NXy)Ar{C(Me)=NOH}-2}Cl(CNXy)] (8) which, in turn, reacted with [AuCl(SMe(2))] to give [Pd{μ-N,C,N-C(=NXy)Ar{C(Me)=NOH}-2}Cl](2) (9) with loss of XyNC. Some of these complexes are, for any metal, the first containing cyclometalated aryloximato (6, 7) or iminoaryloxime (8, 9) ligands. Various crystal structures of complexes of the types 2, 3, 6, 7, 8 and 9 have been determined.

Pincer complexes of the types [Pd{C,N,N′-Ar{C(Me)NOCH2py-2}-2}X] or [Pd{C,N,S-C6H4{C(Me)NOCH2SMe}-2}Cl] (Ar = C6H4, C6H(OMe)3-4,5,6; py-2 = 2-pyridyl; X = Cl, Br) have been prepared by reacting cyclopalladated oxime complexes [Pd{C,N-Ar{C(Me)NOH}-2}(μ-Cl)]2 with XCH2py-2 or ClCH2SMe, respectively, in the presence of KtBuO. Various neutral and cationic derivatives have been synthesized as well as iminobenzoyl complexes resulting from the insertion of isocyanide into their Pd–Caryl bond. The cycloaddition of MeO2CCCCO2Me to the oximato complex [Pd{C,N-C6H4{C(Me)NO}-2}(tBubpy)] (tBubpy = 4,4′-di-tert-butyl-2,2′-bipyridine) in the presence of various neutral L ligands produces pincer complexes [Pd{C,N,C′-C6H4{C(Me)NOC(CO2Me)C(CO2Me)}-2}L]. Complexes of each one of the new types have been characterized by X-ray diffraction methods.

Neutral and cationic six-membered C,N-palladacycles with the core "Pd{C,N-C 6 H 4 {CH 2 C(Me)NOH}-2}" have been obtained by oxidative addition of the oxime BrC 6 H 4 {CH 2 C(Me)NOH}-2 to "Pd(dba) 2 " (dba = dibenzylideneacetone) in the presence of mono-or bidentate ligands. The oximato complex [Pd{μ-C,N,O-C 6 H 4 {CH 2 C-(Me)NO}-2}(PTol 3 )] 2 forms after dehydrobromination of the appropriate oxime complex with K t BuO, while the pincer derivative [Pd{C,N,N′-C 6 H 4 {CH 2 C(Me)NOCH 2 py}-2}Br] results by attack of an in situ generated oximato complex to BrCH 2 py•HBr. Insertion of CO or RNC in some of the palladacycles causes a depalladation/coupling process, giving 1,2-dihydro-1-oxo-2-hydroxy-3-methylisoquinoline or 1,2dihydro-1-imino(R)-2-hydroxy-3-methylisoquinoline, respectively, while the insertion of alkynes produces eight-membered alkenyl(oxime) palladacycles "Pd{C,N-C(R′)C(R)C 6 H 4 {CH 2 C(Me)NOH}-2}". When using diphenylacetylene, a dimeric tetranuclear complex [{Pd(tbbpy)} 2 {μ-N,O-{η 3 -C 6 H 4 (C 4 Ph 4 ){CH 2 C(Me)NO}}}] 2 4+ forms instead, in which a π-allylcoordinated oximato, bearing a spirocyclic substituent, acts as the bridging ligand. The crystal structures of the oxime and of each type of complexes have been determined.

Insertion of CO into the Pd−Caryl bond of complexes [PdI{C6H4{NHC(Me)CHC(O)Me}-2}(N∧N)] afforded the benzoyl derivatives [PdI{C(O)C6H4{NHC(Me)CHC(O)Me}-2}(N∧N)] [N∧N = 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)] (7 Z ), resulting from the insertion of the alkyne into the C(sp2)−H bond of the enaminone substituent. 7 Z isomerized into the E analogue (7 E ) 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, 7 Z , 7 E , and 10 have been determined.

Cyclopalladated benzamidoxime complexes [Pd{C,N-C6H4{C(NH2)[double bond, length as m-dash]NOH}-2}Cl(L)] (L = PTol3, Tol = C6H4Me-4 (); XyNC, Xy = C6H3Me2-2,6 (); pic, C5H4Me-4 ()), [Pd{C,N-C6H4{C(NH2)[double bond, length as m-dash]NOH}-2}(L2)]ClO4 (L = pic (); L2 = 4,4'-di-tert-butyl-2,2'-bipyridine, tbbpy ()) and PPN[Pd{C,N-C6H4{C(NH2)[double bond, length as m-dash]NOH}-2}Cl2] () are prepared by reacting [Pd{C,N-C6H4{C(NH2)[double bond, length as m-dash]NOH}-2}(μ-Cl)]2 () with the appropriate neutral ligand or with [PPN]Cl, respectively. The cationic complexes are obtained in the presence of NaClO4. The reaction of with K(t)BuO affords the dinuclear oximato complex [Pd{μ-C,N,O-C6H4{C(NH2)[double bond, length as m-dash]NO}-2}(PTol3)]2 () or, in the presence of ClCH2py·HCl, the pincer derivative [Pd{C,N,N'-C6H4{C(NH2)[double bond, length as m-dash]NOCH2(C5H4N-2)}-2}(PTol3)]ClO4 (). Complex reacts with XyNC to give the iminobenzoyl complex [Pd{C,N-C(N[double bond, length as m-dash]Xy)C6H4{C(NH2)[double bond, length as m-dash]NOH}-2}Cl(CNXy)] () resulting from the insertion of XyNC into the Pd-C bond. The dinuclear complex [{Pd(tbbpy)}2{C,N,N',O-C6H4{C(NH)[double bond, length as m-dash]NO}-2}]ClO4 () bearing a bridging tetradentate benzimido(oximate) ligand is obtained by reacting Pd(OAc)2 with tbbpy and the metal-ligand complex . The crystal structures of complexes , , and have been determined.