The Pentaamminemethylcobalt(III) Cation: Synthesis and Spectroscopic Characterization

Kofod, Pauli

doi:10.1021/ic00114a040

Cited by 34 publications

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“…Pentaamminemethylcobalt(III) nitrate was prepared according to the method of Kofod, [27] but oxygen was bubbled through the reaction mixture for 4 h instead of exposure to air. The complex was stored under nitrogen in the dark.…”

Section: Methodsmentioning

confidence: 99%

“…The purity of the complex was checked by elemental analysis and 1 H NMR and UV/Vis spectroscopy. [27,28] Ϫ All solutions for the kinetic measurements were freshly prepared with Millipore water in the dark before use. 10% of the total concentration of en was protonated with nitric acid to use en-enH ϩ as buffer.…”

Section: Methodsmentioning

confidence: 99%

“…[4,5,7,9Ϫ26] The simplest model for the B 12 coenzyme was recently synthesized by Kofod and consists of a Co III metal centre surrounded by five ammonia ligands and one methyl group. [27] The X-ray structure shows a large increase in the length of the CoϪN bond trans to the metalϪcarbon bond compared to those of the equatorial positions. [28] An interesting question is to what extent the introduction of a single metalϪcarbon σ-bond affects the substitution behaviour of this Co III complex.…”

Section: Introductionmentioning

confidence: 99%

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Substitution Behaviour of an Alkylcobaltamine Complex − Evidence for a Limiting Dissociative Mechanism

Dücker-Benfer¹,

Hamza²,

Eckhardt³

et al. 2000

Eur. J. Inorg. Chem.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Substitution Behaviour of an Alkylcobaltamine Complex − Evidence for a Limiting Dissociative Mechanism

Dücker-Benfer¹,

Hamza²,

Eckhardt³

et al. 2000

Eur. J. Inorg. Chem.

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“…Much of the study with model complexes reveals that the active part of the coenzyme is the CoÀC bond cleavage, which initiates the enzymatic reaction. The pentammine(methyl)cobalt(III) complex is the simplest model for coenzyme B 12 [1], where four ammine ligands are bound to the Co-center in equatorial positions and one ammine and the methyl ligand are in axial positions trans to each other. Later, cobalamins and cobaloximes were extensively studied.…”

mentioning

confidence: 99%

“…(OC-6-32)-Aquabis(ethane-1,2-diamine-kN,kN')ethyl cobalt(III) (trans-[Co(en) 2 (Et)OH 2 ]) was prepared according to [1] [7b] with ethylhydrazine (R ¼ Et in Scheme 1).…”

mentioning

confidence: 99%

Biomimetic Model of Coenzyme B₁₂: Aquabis(ethane‐1,2‐diamine‐κN,κN′)ethylcobalt(III) – Its Kinetic and Binding Studies with Imidazoles and Amino Acids and Interactions with CT DNA

Pallavi

Nagababu

Satyanarayana

2007

Helvetica Chimica Acta

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Pseudo-first-order reaction kinetics and binding studies of trans-[Co(en) 2 (Et)H 2 O] complex with 1H-imidazole, substituted 1H-imidazoles, histidine, histamine, glycine and glycine ethyl ester were investigated by means of spectrophotometric techniques. Equilibrium constants were determined as a function of pH at 258. Binding and kinetic studies were correlated to basicity and steric hindrance. From the equilibrium data, it was found that the entering nucleophile is participating in the transition state, an I d mechanism is proposed. The effect of the incoming ligands on the complex was studied by molecular mechanics. The interaction of trans-[Co(en) 2 (Et)H 2 O] with CT DNA was studied spectrophotometrically.Introduction. -To understand the mechanistic aspect of coenzyme B 12 , which actively carries many enzymatic reactions, model complexes of the coenzyme are widely studied. Much of the study with model complexes reveals that the active part of the coenzyme is the CoÀC bond cleavage, which initiates the enzymatic reaction. The pentammine(methyl)cobalt(III) complex is the simplest model for coenzyme B 12 [1], where four ammine ligands are bound to the Co-center in equatorial positions and one ammine and the methyl ligand are in axial positions trans to each other. Later, cobalamins and cobaloximes were extensively studied.The carbanion ligand coordinated to the Co III center is influenced by the presence of other ligands in cis or trans position with respect to the carbanion ligand. A cis and trans effect on the CoÀC bond was reported for naturally occurring methylcobalamin [2] and various synthetic complexes such as those with tetrapyrrole, imine, oxime, mixed imine-oxime or ammine ligands [3 -7]. The data for the trans-[Co(DH) 2 (Me)L] (DH ¼ dmg ¼ dimethylglyoximato) revealed that the 13 C-NMR chemical shift, the

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Cobalt: Inorganic & Coordination ChemistryBased in part on the article Cobalt: Inorganic & Coordination Chemistry by David A. Buckingham which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Blackman

2005

Encyclopedia of Inorganic Chemistry

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This article provides a summary of the important and interesting aspects of the inorganic and coordination chemistry of cobalt. A brief history of the element, detailing its discovery and historical uses, is given, and some general information concerning the properties of elemental cobalt is detailed. The general chemistry of cobalt is then outlined, including an overview of the common oxidation states found in inorganic compounds and complexes, a discussion of the stereochemistry, spectra and magnetism of cobalt complexes, and an outline of some analytical methods used for cobalt. The inorganic chemistry of simple cobalt salts is then described, and the coordination chemistry of cobalt, which constitutes the majority of the article, is then outlined in some detail. Coordination complexes of cobalt are detailed according to the oxidation state of the metal ion, with complexes ranging from Co(−I) to Co(V) discussed. Brief descriptions of the chemistry of each oxidation state are given, and specific examples are then outlined according to the nature of the ligand donor atom(s), with extensive references to both the primary literature and to review articles given. Thus, Co(I), Co(0), and Co(−I) complexes containing aliphatic, aromatic, and macrocyclic amine ligands, as well as Schiff‐base, porphyrin, and P‐donor ligands are discussed, while Co(II) complexes of carboxylate, heterocyclic, and oxygen‐derived ligands are summarized. Co(III) ammine and amine complexes are described in detail, while Co(III) complexes containing O‐donor ligands are also discussed. The few known Co(IV) and Co(V) complexes are outlined.

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The Pentaamminemethylcobalt(III) Cation: Synthesis and Spectroscopic Characterization

Cited by 34 publications

References 0 publications

Substitution Behaviour of an Alkylcobaltamine Complex − Evidence for a Limiting Dissociative Mechanism

Substitution Behaviour of an Alkylcobaltamine Complex − Evidence for a Limiting Dissociative Mechanism

Biomimetic Model of Coenzyme B₁₂: Aquabis(ethane‐1,2‐diamine‐κN,κN′)ethylcobalt(III) – Its Kinetic and Binding Studies with Imidazoles and Amino Acids and Interactions with CT DNA

Cobalt: Inorganic & Coordination ChemistryBased in part on the article Cobalt: Inorganic & Coordination Chemistry by David A. Buckingham which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

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The Pentaamminemethylcobalt(III) Cation: Synthesis and Spectroscopic Characterization

Cited by 34 publications

References 0 publications

Substitution Behaviour of an Alkylcobaltamine Complex − Evidence for a Limiting Dissociative Mechanism

Substitution Behaviour of an Alkylcobaltamine Complex − Evidence for a Limiting Dissociative Mechanism

Biomimetic Model of Coenzyme B12: Aquabis(ethane‐1,2‐diamine‐κN,κN′)ethylcobalt(III) – Its Kinetic and Binding Studies with Imidazoles and Amino Acids and Interactions with CT DNA

Cobalt: Inorganic & Coordination ChemistryBased in part on the article Cobalt: Inorganic & Coordination Chemistry by David A. Buckingham which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Contact Info

Product

Resources

About

Biomimetic Model of Coenzyme B₁₂: Aquabis(ethane‐1,2‐diamine‐κN,κN′)ethylcobalt(III) – Its Kinetic and Binding Studies with Imidazoles and Amino Acids and Interactions with CT DNA