- Models for Iron-Oxo Proteins. Structures and Properties of Fe(II)Fe(III), Zn(II)Fe(III), and Fe(II)Ga(III) Complexes with (μ-Phenoxo)bis(μ-carboxylato)dimetal Cores
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A series of bimetallic complexes, X2 where BPMP is the anion of 2,6-bis-4-methylphenol, has been synthesized to provide models for binuclear metal-oxo centers in proteins (1, M = M' = Fe, R = C2H
- Borovik, A. S.,Papaefthymiou, Vasilios,Taylor, Lucille F.,Anderson, Oren P.,Que, Lawrence
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- Synthesis and properties of a heterobimetallic iron-manganese complex and its comparison with homobimetallic analogues
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Heterobimetallic cofactors containing one manganese and one iron ion have recently been found within the di-metal carboxylate protein family. Herein we report the synthesis and characterization of three binuclear metal complexes with Fe-Fe, Mn-Mn, and Fe-Mn metal composition. All three complexes use the same ligand framework, the BPMP ligand (HBPMP = 2,6-bis[(bis (-2-pyridylmethyl)amine) methyl]-4-methylphenol)) with two additional acetate ligands bridging the two metals. In terms of stability towards metal exchange, the Fe-Mn is more stable than the Mn-Mn complex but less stable than the Fe-Fe complex. Cyclic voltammetry shows that the Fe-Mn complex behaves markedly different than the homobimetallic complexes. The Fe-Mn complex also shows higher reactivity with O2 than both the Fe-Fe and the Mn-Mn counterparts.
- Bedin, Michele,Agarwala, Hemlata,Marx, Jennifer,Schünemann, Volker,Ott, Sascha,Thapper, Anders
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p. 254 - 260
(2019/03/28)
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- Synthesis, structure, catalytic and magnetic properties of a pyrazole based five coordinated di-nuclear cobalt(II) complex
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The reaction of 4-methyl-2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)methyl)phenol and Co(NO3)2·6H2O in MeCN gives rise to [Co2(L)2(N3)2] (1), a dinuclear five coordinated complex of Co(II), in satisfactory yield. The complex has been characterized by C, H and N microanalyses, FT-IR and UV-Vis spectral measurements. A single crystal X-ray diffraction study of 1 reveals that each Co(II) atom is in a distorted square-pyramidal geometry. Electrochemical studies in CH3CN showed that the Co(II)-Co(III)/Co(III)-Co(III) redox couple appears to be quasi-reversible (E1/2 = 0.409 V), while the corresponding Co(II)-Co(III)/Co(II)-Co(II) couple is mostly irreversible (E1/2 = -0.447 V). This complex displays modest catalytic activity toward the oxidation of various allylic compounds using TBHP as an oxidant in MeCN under mild conditions. A radical trapped experiment carried out in the presence of 4-tert-butylphenol clearly reveals that the epoxidation reactions occur purely through a radical pathway rather than a concerted one. Low temperature magnetic studies showed that the present Co(II) dimeric complex possesses a high positive magnetic anisotropy (D = +29.8 cm-1) and a weak ferromagnetic exchange interaction (2J = +10.3 cm-1).
- Alam, Rabiul,Pal, Kaberi,Shaw, Bikash Kumar,Dolai, Malay,Pal, Nabanita,Saha, Shyamal Kumar,Ali, Mahammad
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- Nickel-catalyzed one-pot deoxygenation and reductive homocoupling of phenols via C-O activation using TCT reagent
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A new method for C-O bond activation of phenolic compounds has been achieved using 2,4,6-trichloro-1,3,5-triazine to utilize in one-pot Ni-catalyzed deoxygenation and reductive homocoupling reactions. With this simple method, phenolic compounds were converted to their corresponding arenes or biaryl compounds under mild conditions. The introduced methodology has a broad scope and demonstrates good functional group compatibility.
- Iranpoor, Nasser,Panahi, Farhad
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p. 214 - 217
(2015/01/30)
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- (ArO)TiR3 complexes for highly syndiospecific styrene polymerization
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A kind of (ArO)TiR3 (ArO = 2,6-(R′)2-4- methylphenolate, R′ = Me, tBu, CH2SPh, CH 2N(iPr)2, CH2NPh2) complexes was synthesized and characterized. X-ray analysis of 6a and 7 shows that neither CH2SPh (6a) nor CH2N(iPr) 2 group (7) coordinates to titanium. Large bond angles C(Ar)-O(1)-Ti(1) angel (152.9(2) in 6a and 175.33 in 7 indicate that the bond have partial sp-hybridized character. Upon treatment with modified methylaluminoxane (MMAO), the titanium complexes exhibit significant thermal stability, and prove useful as styrene syndiotactic polymerization catalysts. Comparisons between different complexes on the styrene polymerization were discussed. Steric instead of electronic properties at 2,6-positions of phenol affect the polymerization activity. (2-tert-Butyl)-4-methylphenoxytitanium(IV) chloride 5e was established the most efficient one. High activity (1.11 × 105 g sPS/mol(Ti) h) was achieved when styrene polymerization was carried out in the presence of 5e/MMAO at 130 C for 2 h.
- Xu, Chongjie,Chen, Zhou,Ji, Gang,Sun, Xiu-Li,Li, Jun-Fang,Tang, Yong
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- Synthesis and characterization of oligonuclear Ru, Co and Cu oxidation catalysts
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In this work, we report the preparation and crystal structures of three new oligonuclear complexes, Ru2(bbpmp)(μ-OAc)3 (4), [Co2(bbpmp)(μ-OAc)(μ-OMe)](PF6) (5), [Cu 4(Hbbpmp)2(μ-OAc)(H2O)2](OAc)(PF 6)2 (6) {H3bbpmp = 2,6-bis[(2-hydroxybenzyl)- (2-pyridylmethyl)aminomethyl]-4-methyl-phenol (3)}. The structures of the complexes were determined by single-crystal X-ray diffraction. The oxidation states of ruthenium, cobalt and copper in the complexes are +3, +3 and +2, respectively. In 4 and 5, RuIII and CoIII are coordinated to four oxygen and two nitrogen atoms in an octahedral geometry, while in 6, CuII adopts both octahedral (CuN2O4) and square-pyramidal (CuN2O3) geometry. The potential of the three complexes as oxidation catalysts has been investigated. Copyright
- Lee, Bao-Lin,Kaerkaes, Markus D.,Johnston, Eric V.,Inge, Andrew K.,Tran, Lien-Hoa,Xu, Yunhua,Hansson, Oerjan,Zou, Xiaodong,Akermark, Bjoern
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experimental part
p. 5462 - 5470
(2011/03/01)
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- Symmetrical and unsymmetrical dizinc complexes as models for the active sites of hydrolytic enzymes
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Dinuclear carboxylate-bridged zinc complexes of one symmetric and one asymmetric phenolate-based ligand catalyse the transesterification of 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) at different rates, with an unsymmetrical complex being more active than a symmetric one. The Royal Society of Chemistry.
- Jarenmark, Martin,Kappen, Sascha,Haukka, Matti,Nordlander, Ebbe
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p. 993 - 996
(2008/09/20)
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- Asymmetric synthesis of hydrobenzofuranones via desymmetrization of cyclohexadienones using the intramolecular Stetter reaction
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Dearomatization of phenols followed by oxidation affords cyclohexadienyloxyacetaldehydes, which produce hydrobenzofuranones via asymmetric intramolecular Stetter reaction in good to excellent yield. Quaternary as well as up to three contiguous stereocenters may be formed in good to excellent enantioselectivities and high diastereoselectivities. Copyright
- Liu, Qin,Rovis, Tomislav
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p. 2552 - 2553
(2007/10/03)
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- LIGANDS AND COMPLEX COMPOUNDS CONTAINING THE SAME
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A ligand represented by the formula (1):R1R2N-Q1-X-Q2-NR3R4 wherein R1, R2, R3 and R4 are each the same or different and represent a group repres
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Page/Page column 8
(2010/02/14)
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- Synthesis and characterisation of a high valent dinuclear Mn(III,III) complex of a triphenolate ligand [N4O3]3- with two extra functional groups
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A new high valent complex [Mn2(III,III)L(μ-OAc) 2]·PF6 7 was prepared, where L was the tri-anion of 2,6-Bis {[(2-hydroxy-5-tert-butylbenzyl)(pyridyl-2-methyl)amino]methyl}-4-methylphenol which contained two additional phenolate groups and two tert-butyl groups compared to its parent [Mn2(II,II)(bpmp)(μ-OAc) 2]·PF6. These improvements narrowed the disparity between the new model and (Mn)4 cluster (OEC in nature).
- Li, Hongyang,Shi, Feng,Gao, Yan,Zhang, Rong,Peng, Xiaojun,Sun, Licheng
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- Synthesis and characterization of a dinuclear manganese(III,III) complex with three phenolate ligands
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A dinuclear manganese complex ([Mn2L(μ-OAc)2]PF6) has been synthesized, where L is the trianion of 2,6-bis{[(2-hydroxy-3,5-di-tert-butylbenzyl) (2-pyridylmethyl)amino]-methyl}-4-methylphenol, a ligand with three phenolate
- Lomoth, Reiner,Huang, Ping,Zheng, Jiutian,Sun, Licheng,Hammarstroem, Leif,Akermark, Bjoern,Styring, Stenbjoern
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p. 2965 - 2974
(2007/10/03)
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- A convergent synthesis of hexahomotriazacalix[3]arene macrocycles
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A new, convergent synthesis of hexahomotriazacalix[3]arenes 1a-e is described. The key transformation in this synthesis involves the coupling of the triamines 4a-d with 2,6-bis-(chloromethyl)-4-methylphenol 5 and results in the formation of the hexahomotriazacalix[3] arenes 1a-d in 90-95% yield. The triamines 4a-d were constructed by the one-pot reaction of monochloroaldehyde 3 and a primary amine followed by reduction to yield the triamines 4a-d in 50-55% yield. Deallylation of macrocycle 1d was accomplished by palladium catalysis to obtain the N-unsubstituted macrocycle 1e, which has the potential to be a precursor to a variety of N-substituted hexahomotriazacalix[3]arenes.
- Chirakul,Hampton,Bencze
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p. 8297 - 8300
(2007/10/03)
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- Syntheses and properties of chiral tricyclic compounds bridged by cystine units
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Novel chiral tricyclic compounds were prepared from the reactions of the cystine dimethyl ester and 4-substituted 2,6-bis(chloromethyl)phenol derivatives. The 1H-NMR and CD spectra showed the existence of chiral twisting of the cyclophane unit,
- Ito, Kazuaki,Ohba, Yoshihiro,Sone, Tyo
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p. 2203 - 2212
(2007/10/03)
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- Production of organic compounds
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Pyrogallol, and analogues thereof having an alkyl, carboxy or alkoxycarbonyl substituent in the benzene ring, and their salts, are prepared by oxidizing, preferably by hydrogen peroxide, the corresponding compounds in which 1 or 2 of the OH groups are replaced by --COR5 groups where R5 represents hydrogen, alkyl or phenylalkyl. The production of intermediates is also described and some of these are novel.
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