Cyclometallated compounds

Phillips, Ian G.; Steel, Peter J.

doi:10.1016/0022-328x(91)80010-h

Cited by 261 publications

(15 citation statements)

References 37 publications

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“…Chart 1 Types of aryloxime (1)(2)(3)(4)(5), aryloximato (6)(7) and iminoaryloxime (8)(9) palladium complexes included in this paper. The numbering scheme used in NMR assignments is depicted in 1.…”

Section: Introductionmentioning

confidence: 99%

A systematic study on the synthesis, reactivity and structure of ortho-palladated aryloximes, including the first cyclopalladated aryloximato and iminoaryloxime complexes

et al. 2012

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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.

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Section: Introductionmentioning

confidence: 99%

A systematic study on the synthesis, reactivity and structure of ortho-palladated aryloximes, including the first cyclopalladated aryloximato and iminoaryloxime complexes

et al. 2012

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“…Those leading to mononuclear monopalladated complexes of a single ligand form the vast majority. , The notation 1M1C1L in Chart means that the cyclometalated complex has one metal atom bonded to one C atom of one ligand. In this group of cyclopalladation reactions, those giving N,C,N or P,C,P pincer complexes 10,62-69 and dipalladated complexes obtained by cyclometalation of a single ligand (2M2C1L) are increasingly being reported. ,,,− Much more scarce are those cyclopalladation reactions involving two C−H bond activations per palladium atom. Two kinds of complexes have been isolated from these cyclopalladation reactions: 1M2C1L and 1M2C2L (see Chart ).…”

Section: Introductionmentioning

confidence: 99%

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

et al. 1999

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[PdCl2(NCPh)2] reacts with R−carbonylmethylenethiopyridines [py{SCH2C(O)R}-2] to give, depending on the substituent R and the reaction conditions, or the coordination complexes [Pd{py{SCH2C(O)R}-2}2Cl2] (R = Ph, Me, OMe). The latter can be doubly deprotonated by a base (Na2CO3 or NaH) to give dicyclometalated complexes These transmetalate one ligand to [PdCl2(NCPh)2] to give which in turn reacts with (Me4N)Cl or with monodentate ligands L or with MeCN in the presence of AgClO4 to give anionic neutral [R = Ph, L = PPh3, py{SCH2C(O)Ph}-2, tBuNC, NH2CH(Me)Ph, pyridine (py), tetrahydrothiophene (tht); R = Me, L = PPh3, py, tht], or cationic (R = Ph, Me, OMe) complexes, respectively. The latter react with PPh3 or with bidentate ligands to give complexes or [L = PPh3, L2 = N,N,N‘,N‘-tetramethylethylenediamine (tmeda) or 2,2‘-bipyridine (bipy)]. The crystal structures of and have been determined.

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“…There, the naphthalene peri-position (C(8)) was only accessible to cyclopalladation after all the ortho-positions had been blocked by methyl groups [25] [26]. Also, if the donor atom is directly attached to the naphthalene C(1), the only possibility to form a five-membered inetallacycle is the metallation at position C (8) [l] [18] [19]. Furthermore, indirect cyclometallation methods (as e.g., transmetallations [29] or ligand-exchange reactions [30]) provide a way to peri-metallated naphthalene moieties [31-341. For the Schifjr bases with the structural formula shown in Scheme f, however, the cyclopalladation with palladium acetate in AcOH always yields a mixture of ortho-and peri-palladated complexes, the regioselectivity being dependent on the reaction temperature [21]: For the cyclometalland with R = H, increasing the reaction temperature favors the formation of the pevz-palladated product, whereas the contrary holds true for the Schiff base with R = M e 0 (Scheme I ) .…”

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Cyclopalladation of 1,1′‐Azonaphthalene (= Di(naphthalen‐1‐yl)diazene): Isolation and characterization of two isomeric complexes

Kind¹,

Klaus²,

Rys³

et al. 1998

Helvetica Chimica Acta

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The cyclopalladation of 1 ,l'-azonaphthalene (= di(naphtha1en-I -yl)diazene; 2) with bis(hexafluoroacety1-acetonato)palladium(II) (3; [Pd(hfa),]) yields the ortho-palladated complex (1,1,1,5,5,5-hexafluoropentane-2,4-dionato-fc20,0')[i -(naphthalen-l-ylaro-~~2)naphthalen-2-yl-~Cz]palladium(II) (4) as well as the peri-palladated complex (1,1,1,5,5,5-hexafluoropentane-2,4-d~onato-~~0,O)[8-(naphthalen-l-ylazo-~~~)naphthalen-l-yl-~C']-palladium(I1) (5); their structures were corroborated by X-ray analyses. The formation of the novel peri-metallated product 5 containing a six-membered palladacycle strongly depends upon the reaction conditions.Introduction. -The cyclometallation reaction -albeit described for the first time some 25 years ago [l] [2] -still has an enormous potential as a synthetic tool when employed for the ortho-functionalization of suitable arenes [3 -81. Only recently, cyclopalladated complexes were described that catalyze the Heck olefination [9] or aryl-coupling reactions [lo] in homogeneous solution with high turnover numbers. Other cyclopalladated complexes exhibit some promising liquid-crystalline [ l l -131 or photochemical and electrochemical [14-161 properties. The cyclometallation principle can also be applied effectively to the laboratory-scale syntheses of dyestuff molecules and dyestuff precursors [17].Whereas the papers on investigations of the C-H activation at phenylic ortho-positions 'are copious, far less has been reported on the cyclometallation of naphthalene moieties so far [6][18-281, despite the fact that the naphthalene ring is more reactive towards electrophilic cyclometallating agents. Furthermore, naphthalenes with donorbearing substituents at C( 1) offer both the ortho-and the peri-position for the cyclometallation.To make 1-substituted naphthalenes like naphthalen-1-amine (1) amenable to cyclopalladation, they have to be converted into suitable donor-bearing cyclometallands, as, e.g., the corresponding 1 ,If-azonaphthalene (= di(naphtha1en-1-y1)diazene ; 2). Transforming the original naphthalen-1-amine (1) into the symmetrical 1 ,l'-azonaphthalene (2) has several advantages: this cyclometalland is providing a donor atom for each of the two naphthalene moieties, and the desired functional groups can be introduced into both rings by two separate metallation/cleavage sequences. Finally, the bis-ortho-substituted azonaphthalene would yield two identical ortho-functionalized naphthalen-1-amines upon complete reduction of the azo bridge.The cyclopalladation of the unsubstituted 1 ,l'-azonaphthalene (2) is expected to occur at the C(2) center ortho to the azo bridge, as was shown earlier for various 1 -(phenylazo)naphthalenes [26] [27]. There, the naphthalene peri-position (C(8)) was only

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Cyclometallated compounds

Cited by 261 publications

References 37 publications

A systematic study on the synthesis, reactivity and structure of ortho-palladated aryloximes, including the first cyclopalladated aryloximato and iminoaryloxime complexes

A systematic study on the synthesis, reactivity and structure of ortho-palladated aryloximes, including the first cyclopalladated aryloximato and iminoaryloxime complexes

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

Cyclopalladation of 1,1′‐Azonaphthalene (= Di(naphthalen‐1‐yl)diazene): Isolation and characterization of two isomeric complexes

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Cyclometallated compounds

Cited by 261 publications

References 37 publications

A systematic study on the synthesis, reactivity and structure of ortho-palladated aryloximes, including the first cyclopalladated aryloximato and iminoaryloxime complexes

A systematic study on the synthesis, reactivity and structure of ortho-palladated aryloximes, including the first cyclopalladated aryloximato and iminoaryloxime complexes

Multidonor Ligands. 3. Cyclopalladation of py{SCH2C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp3)−H Bond Activation

Cyclopalladation of 1,1′‐Azonaphthalene (= Di(naphthalen‐1‐yl)diazene): Isolation and characterization of two isomeric complexes

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Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation