Reactions of some substituted phenols with chromyl and vanadyl chlorides

1980 ◽  
Vol 58 (7) ◽  
pp. 686-693 ◽  
Author(s):  
John F. Harrod ◽  
Asha Pathak
Keyword(s):  
Metal Complexes ◽  
Oxidation Potential ◽  
Lewis Acidity ◽  
Substituted Phenols ◽  
Phenoxyl Radicals ◽  
Organic Group ◽  
Product Distributions ◽  
Carbenium Ion ◽  
Electron Withdrawal ◽  
Ligand Transfer

The oxidation of 2,4,6-tritertbutylphenol and several other alkyl and halophenols by CrO2Cl2 and VOCl3 was studied. The products of CrO2Cl2 oxidation are mostly quinones and diphenoquinones, whilst those of VOCL3 oxidation also include major amounts of dealkylated phenols and C—C coupled dimers. The product distributions are interpreted in terms of a mechanism involving phenoxyl radicals, ligand transfer from metal to radical, and either phenoxonium ions or metallate esters where there is sufficient electron withdrawal from the organic group for it to exhibit carbenium ion properties. The differences in behaviour between CrO2Cl2, VOCl3, and CuCl2 are attributed to different balances between the oxidation potential and Lewis acidity of the metal complexes. It is concluded that CrO2Cl2 is not a good model for proposed ferryl intermediate in heme oxidase systems since it induces 1 → 3 rather than 1 → 2 halogen shifts and an NIH shift that is best explained by carbenium ion-like intermediates.

Molecular assemblies based on strong axial coordination in metal complexes of saddle-distorted dodecaphenylporphyrins

2015 ◽  
Vol 19 (01-03) ◽  
pp. 32-44 ◽  
Author(s):  
Tomoya Ishizuka ◽  
Shunichi Fukuzumi ◽  
Takahiko Kojima
Keyword(s):  
Electron Transfer ◽  
Metal Ions ◽  
Metal Complexes ◽  
Photoinduced Electron Transfer ◽  
Oxidation Potential ◽  
Metal Center ◽  
Lewis Acidity ◽  
Central Metal ◽  
Axial Coordination ◽  
Keggin Type

In this mini-review, we have highlighted our works on metal complexes having saddle-distorted dodecaphenylporphyrin (DPP) and its derivative as ligands in the light of enhancement of the Lewis acidity of a metal center coordinated by the porphyrin. The important point through this mini-review is ill-overlap of the out-of-plane lone pairs of pyrrole nitrogen atoms with σ-orbitals of the metal center bound to the saddle-distorted porphyrin core. The enhanced Lewis acidity of the central metal ions enabled us to construct stable molecular complexes through axial coordination using metal–DPP (M(DPP)) moieties ( M = Mo V or Sn IV ) and molecular or ionic entities with Lewis-basic coordination sites, including Keggin-type polyoxometallates (POM), which are known to have weak Lewis basicity and thus hard to coordinate to metal ions. A discrete 1:2 complex with a Ru -substituted POM performs catalytic substrate oxidation reactions in organic solvents. A 1:1 complex between Sn IV ( DPP ) and a Keggin-type POM exhibited photoinduced electron transfer, in which the Sn IV ( DPP ) moiety acts as an electron donor and the POM as an electron acceptor. Besides POM, other electron acceptors, including μ3-oxo trinuclear Ru III clusters and anthraquinone, having carboxyl groups as a linker unit also formed stable complexes with DPP-metal complexes as axial ligands to perform photoinduced electron transfer. Successful photoreactions of the M(DPP)-acceptor complexes are mainly enabled by the enhanced Lewis acidity of the DPP-metal complexes for the stabilization of the assemblies and also by lowering the oxidation potential of the porphyrin ligand to gain larger driving force of electron transfer to form an electron-transfer state with avoiding intersystem crossing. The stability and photochemical behavior are in sharp contrast to those for metal complexes with planar porphyrins as ligands.

Evaluation of the Lewis acidity of metal complexes using ESI mass spectrometry

2020 ◽  
Vol 26 (5) ◽  
pp. 332-340
Author(s):  
Rong Zhang ◽  
Ping-Ping Li ◽  
Ge-Ge Gu ◽  
Wei-Min Ren
Keyword(s):  
Mass Spectrometry ◽  
Metal Complexes ◽  
Density Functional ◽  
Lewis Base ◽  
Lewis Acidity ◽  
Ionization Mass ◽  
Base Pairs ◽  
Esi Ms ◽  
Tetradentate Schiff Base ◽  
Schiff Base Metal Complexes

Metal complexes have extensive applications in catalysis, however, the efficient evaluation of Lewis acidity of metal complexes is still a challenge. Herein, we report a method by using electrospray ionization mass spectrometry (ESI-MS) to evaluate the Lewis acidity of metal complexes in the presence of a reference Lewis base, in which the value of the Lewis acidity can be quantized by the bond dissociation energy (BDE) of the resultant Lewis acid-base pairs. Using this method, the Lewis acidity of tetradentate Schiff-base metal complexes (designated as salenMX), a class of common metal complexes in the homogeneous catalysis, was studied in detail. For the salenM(III)X complexes (M = Al, Cr, Fe, Co), the Lewis acidity tendency is Al > Cr > Fe > Co due to a strong affinity between the Al complex and the reference Lewis base while a weak affinity concerning on the Co complex. Additionally, the effect of ligand steric and electronic nature on the Lewis acidity was studied by using Co complex. Furthermore, density functional theory (DFT) was employed to calculate the BDE, which consists with the results obtained from ESI-MS. The ESI-MS method provides a convenient and efficient method for evaluating the Lewis acidity of metal complexes.

Übergangsmetallkomplexe mit Schwefelliganden, LXXVIII. H+-, Lewis-Säure-Basen- und Ligandentransferreaktionen von Thioether-Thiolat-Nickelkomplexen. Röntgenstrukturanalysen von [Mo(O)(′OS4′ )] und [Mo(O)(′NhS4′)]/Transition Metal Complexes with Sulfur Ligands, LXXVIII. H+-, Lewis Acid-Base and Ligand Transfer Reactions of Thioether-Thiolato-Nickel Complexes. X-Ray Structure Determinations of [Mo(O)('OS4')] and [Mo(O)('NHS4')]

1992 ◽  
Vol 47 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Dieter Sellmann ◽  
Stefan Fünfgelder ◽  
Falk Knoch
Keyword(s):  
Metal Complexes ◽  
Acid Methyl Ester ◽  
Transfer Reactions ◽  
Side Chain ◽  
X Ray ◽  
Thiolate Ligands ◽  
Convenient Synthesis ◽  
Structure Determinations ◽  
Ligand Transfer ◽  
Amino Propionic Acid

In order to elucidate specific properties of nickel sulfur complexes, reactions of recently synthesized [Ni('S5')], [Ni('OS4')]2, [Ni('NHS4')]2, [Ni('S4-C5')]2 and [Ni('S4-C3')] were investigated ('OS4'2- = 2,2'-bis(2-mercaptophenylthio)diethylether(2-), 'NHS4'2- = 2,2'-bis(2-mercaptophenylthio)diethylamine(2-), 'S5'2- = 2,2'-bis(2-mercaptophenylthio)diethylsulfide(2-), 'S4-C5'2- = 1,5-bis(2-mercaptophenylthio)pentane(2-), 'S4-C3'2- = 1,3-bis(2-mercaptophenylthio)propane(2-)).Reactions with proton acids, CH3COCl and cyanide led to de-coordination of the sulfur ligands, thus providing a convenient synthesis of multidentate thioether-thiolate ligands.The reactions of these Ni complexes with metal salts or metal complexes led to ligand transfer from nickel to Pd(II), Mo(IV ) and Hg(II), [Pd('S4-C3')], [Hg('S5')], [Hg('S4-C3')]. [Hg('S4-C5')], [Mo(O)('S5')], [Mo(O)('NHS4')] and [Mo(O)('OS4')] were synthesized by this method. X-ray structure analysis proved that [Mo(O)('OS4')] and [Mo(O)('NHS4')] have a pseudooctahedral Mo coordination with cis-thiolate atoms and trans-ether or amine and oxogroup donors.Template alkylation of [Fe(CO)2(S2C6H4)2]2- by 3-(N, N-bis-(2-bromoethyl)-amino)-propionic acid methyl ester leads to a multidentate ligand that contains functional groups in the side chain.

Cyclobutadiene–metal complexes. XI. Tetramethylcyclobutadienecobalt(I) complexes

1967 ◽  
Vol 45 (18) ◽  
pp. 2017-2021 ◽  
Author(s):  
R. Bruce ◽  
P. M. Maitlis
Keyword(s):  
Metal Complexes ◽  
Low Temperatures ◽  
Transfer Reaction ◽  
Quantitative Yield ◽  
Dicobalt Octacarbonyl ◽  
Nickel Tetracarbonyl ◽  
Ligand Transfer

The ligand-transfer reaction of tetramethylcyclobutadienenickel chloride dimer with dicobalt octacarbonyl gave tetramethylcyclobutadienedicobalt hexacarbonyl [Me4C4Co(CO)2Co(CO)4] and nickel tetracarbonyl. Triphenylphosphine replaced one carbonyl in Me4C4Co(CO)2·Co(CO)4 to give Me4C4Co(CO)2·Co(CO)3PPh3. Both Me4C4Co(CO)2·Co(CO)4 and Me4C4Co(CO)2·Co(CO)3PPh3 underwent cleavage with iodine at low temperatures to give tetramethylcyclobutadienecobalt dicarbonyl iodide (Me4C4Co(CO)2I); this was also obtained in quantitative yield from [Me4C4NiI2]2 and Co2(CO)8. One carbonyl in Me4C4Co(CO)2I was replaced on reaction with triphenylphosphine, giving Me4C4Co(CO)(PPh3)I. Me4C4Co(Co)2I reacted with both sodium cyclopentadienide and [C5H5Fe(CO)2]2 to give (π-cyclopentadienyl)-(π-tetramethylcyclobutadiene) cobalt.

scholarly journals New acid dyes and their metal complexes based on substituted phenols for leather: Synthesis, characterization and optical studies

2017 ◽  
Vol 15 (4) ◽  
pp. 346-355 ◽  
Author(s):  
Ghulam Hussain ◽  
Nasir Abass ◽  
Ghulam Shabir ◽  
Makshoof Athar ◽  
Aamer Saeed ◽  
...  
Keyword(s):  
Metal Complexes ◽  
Substituted Phenols ◽  
Acid Dyes ◽  
Optical Studies

Metal Complexes in Oxidic Matrices

1992 ◽  
Vol 271 ◽  
Author(s):  
Ulrich Schubert ◽  
Boris Breitscheidel ◽  
Hermann Buhler ◽  
Christian Egger ◽  
Wlodzimierz Urbaniak
Keyword(s):  
Metal Complex ◽  
Metal Complexes ◽  
Sol Gel ◽  
Ceramic Matrix ◽  
Metal Particles ◽  
Homogeneous Catalysts ◽  
Organic Group ◽  
Catalytically Active ◽  
Group A ◽  
Gel Processing

ABSTRACTAlkoxides of the type (RO)nE-X-A in which a functional organic group A is connected to the alkoxide moiety via an inert and hydrolytically stable spacer X, are used to bind metal complex moieties. Sol-gel processing of the resulting metal complexes [(RO)nE-X-A]yMIm under standard conditions results in the formation of metal complex containing gels. If the metal complex moiety MLm is catalytically active, this method results in the heterogenization of homogeneous catalysts. Another application of the metal complex substituted gels is the preparation of composites containing uniform, nanometer-sized metal particles homogeneously dispersed in a ceramic matrix.

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