Abstraction of Methyl from Neutral Fischer-Type Carbene Complexes:  A New Site for Nucleophilic Attack

1997 ◽  
Vol 16 (3) ◽  
pp. 490-493 ◽  
Author(s):  
Laurence M. Toomey ◽  
Jim D. Atwood
Keyword(s):  
Nucleophilic Attack ◽  
Carbene Complexes

The reactivity of cyclic germoxycarbene complexes of manganese and rhenium towards nucleophiles

1976 ◽  
Vol 54 (16) ◽  
pp. 2557-2562 ◽  
Author(s):  
M. J. Webb ◽  
W. A. G. Graham
Keyword(s):  
Infrared Spectra ◽  
Empirical Formula ◽  
Sodium Methoxide ◽  
Lithium Bromide ◽  
Subsequent Treatment ◽  
Nucleophilic Attack ◽  
Tetraethylammonium Bromide ◽  
Carbene Complexes ◽  
Methoxide Ion

Several acylate salts and noncyclic carbene complexes of manganese and rhenium, containing organogermanium ligands, have been prepared via the reactions of the cyclic germoxycarbene complexes of empirical formula Ph2GeM(CO)4COMe (M = Mn, Re) with the nucleophiles methyllithium or methoxide ion. In each case the observed product could be rationalized in terms of nucleophilic attack at germanium. Treatment of Ph2GeRe(CO)4COMe with methyllithium, followed by ethylation with aqueous Et3OBF4, afforded cis-Ph2MeGeRe(CO)4C(OEt)Me. The manganese analog of this product could be obtained if excess methyllithium were used in the first step. The use of a deficit of methyllithium, however, followed by ethylation, yielded cis-Ph2FGeMn(CO)4C(OEt)Me. Solution infrared spectra have indicated that lithium methoxide and lithium bromide impurities in the methyllithium are involved in this reaction. The reaction of Ph2GeMn(CO)4COMe with sodium methoxide is presumed to involve nucleophilic attack at germanium to give a methoxygermanium species. Subsequent treatment with aqueous tetraethylammonium bromide gave the hydroxygermanium complex, [cis-Ph2(HO)GeMn(CO)4C(O)Me][Et4N]. Ethylation of the same species with aqueous Et3OBF4 afforded cis-Ph2FGeMn(CO)4C(OEt)Me.

Übergangsmetall-Carbin-Komplexe, LI Neue Carben-Komplexe des Mangans durch Umsetzung kationischer Carbin-Komplexe mit Nukleophilen /Transition Metal Carbyne Complexes, LI Novel Carbene Complexes of Manganese by Reaction of Cationic Carbyne Complexes with Nucleophiles

1979 ◽  
Vol 34 (9) ◽  
pp. 1186-1189 ◽  
Author(s):  
Ernst Otto Fischer ◽  
Gerhard Besl
Keyword(s):  
Transition Metal ◽  
Nucleophilic Attack ◽  
Carbene Complexes ◽  
Carbene Complex ◽  
Spectroscopic Investigations ◽  
Carbyne Complexes

Abstract Noveldicarbonyl(π-cyclopentadienyl)-or dicarbonyl (π-methylcyclopentadienyl)-(methylcarbyne)manganese tetrachloroborates (4 or 4 a)result from the reaction of dicarbonyl(π-cyclopentadienyl)-ordicarbonyl(π-methylcyclopentadienyl)[methoxy(methyl)- carbene]manganese (3 or 3 a)with boron trichloride.The reactions of 4 or 4 a with potassium isothiocyanate and of 4 a with lithium cyclopentadienide lead via nucleophilic attack of the anions to neutral carbene complexes.Dicarbonyl(π-cyclopentadienyl) (phenyl-carbyne) manganese tetrachloroborate (1) reacts with cyanate yielding a isocyanate-(phenyl)carbene complex. Conditions of preparation, properties and spectroscopic investigations are reported.

Mechanochemical changes on cyclometalated Ir(iii) acyclic carbene complexes – design and tuning of luminescent mechanochromic transition metal complexes

2020 ◽  
Vol 7 (3) ◽  
pp. 786-794 ◽  
Author(s):  
Jingqi Han ◽  
Kin-Man Tang ◽  
Shun-Cheung Cheng ◽  
Chi-On Ng ◽  
Yuen-Kiu Chun ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Carbene Complexes ◽  
New Class

A new class of luminescent cyclometalated Ir(iii) complexes with readily tunable mechanochromic properties derived from the mechanically induced trans-to-cis isomerization have been developed.

A Conserved Asparagine in a Ubiquitin Conjugating Enzyme Positions the Substrate for Nucleophilic Attack

2018 ◽  
Author(s):  
Walker M. Jones ◽  
Aaron G. Davis ◽  
R. Hunter Wilson ◽  
Katherine L. Elliott ◽  
Isaiah Sumner
Keyword(s):  
Molecular Dynamics ◽  
Quantum Mechanics ◽  
Molecular Mechanics ◽  
Reaction Rates ◽  
Nucleophilic Attack ◽  
Classical Molecular Dynamics ◽  
Ubiquitin Conjugating Enzyme ◽  
Conjugating Enzyme

We present classical molecular dynamics (MD), Born-Oppenheimer molecular dynamics (BOMD), and hybrid quantum mechanics/molecular mechanics (QM/MM) data. MD was performed using the GPU accelerated pmemd module of the AMBER14MD package. BOMD was performed using CP2K version 2.6. The reaction rates in BOMD were accelerated using the Metadynamics method. QM/MM was performed using ONIOM in the Gaussian09 suite of programs. Relevant input files for BOMD and QM/MM are available.

Atom Condensed Fukui Function for Condensed Phases and Biological Systems and Its Application to Enzymatic Fixation of Carbon Dioxide

2019 ◽  
Author(s):  
Javier Oller ◽  
David A. Sáez ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Molecular System ◽  
Chemical Reactivity ◽  
Nucleophilic Attack ◽  
Stable Conformation ◽  
Fukui Functions ◽  
Reactivity Descriptors ◽  
Dynamics Simulations ◽  
Fixation Of Carbon Dioxide

<div><div><div><p>Local reactivity descriptors such as atom condensed Fukui functions are promising computational tools to study chemical reactivity at specific sites within a molecule. Their applications have been mainly focused on isolated molecules in their most stable conformation without considering the effects of the surroundings. Here, we propose to combine QM/MM Born-Oppenheimer molecular dynamics simulations to obtain the microstates (configurations) of a molecular system using different representations of the molecular environment and calculate Boltzmann weighted atom condensed local reac- tivity descriptors based on conceptual DFT. Our approach takes the conformational fluctuations of the molecular system and the polarization of its electron density by the environment into account allowing us to analyze the effect of changes in the molecular environment on reactivity. In this contribution, we apply the method mentioned above to the catalytic fixation of carbon dioxide by crotonyl-CoA carboxylase/reductase and study if the enzyme alters the reactivity of its substrate compared to an aqueous solution. Our main result is that the protein en- vironment activates the substrate by the elimination of solute-solvent hydrogen bonds from aqueous solution in the two elementary steps of the reaction mechanism: the nucleophilic attack of a hydride anion from NADPH on the α, β unsaturated thioester and the electrophilic attack of carbon dioxide on the formed enolate species.</p></div></div></div>

Metal-N-Heterocyclic Carbene Complexes as Anti-Tumor Agents

2014 ◽  
Vol 21 (10) ◽  
pp. 1220-1230 ◽  
Author(s):  
Chunqi Hu ◽  
Xin Li ◽  
Wei Wang ◽  
Ruoyu Zhang ◽  
Liping Deng
Keyword(s):  
Carbene Complexes
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