Clusters containing carbene ligands. Novel example of carbene ligand transfer from a metal atom to a carbon atom

1990 ◽  
Vol 9 (11) ◽  
pp. 2882-2883 ◽  
Author(s):  
Richard D. Adams ◽  
Gong Chen
Keyword(s):  
Carbon Atom ◽  
Metal Atom ◽  
Carbene Ligands ◽  
Ligand Transfer

scholarly journals Carbones and Carbon Atom as Ligands in Transition Metal Complexes

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4943 ◽  
Author(s):  
Lili Zhao ◽  
Chaoqun Chai ◽  
Wolfgang Petz ◽  
Gernot Frenking
Keyword(s):  
Carbon Atom ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Metal Atom ◽  
Lanthanide Complexes ◽  
Theoretical Studies ◽  
Complete Coverage ◽  
Review Reports ◽  
Experimental And Theoretical Studies

This review summarizes experimental and theoretical studies of transition metal complexes with two types of novel metal-carbon bonds. One type features complexes with carbones CL2 as ligands, where the carbon(0) atom has two electron lone pairs which engage in double (σ and π) donation to the metal atom [M]⇇CL2. The second part of this review reports complexes which have a neutral carbon atom C as ligand. Carbido complexes with naked carbon atoms may be considered as endpoint of the series [M]-CR3 → [M]-CR2 → [M]-CR → [M]-C. This review includes some work on uranium and cerium complexes, but it does not present a complete coverage of actinide and lanthanide complexes with carbone or carbide ligands.

Oxygen uptake and evolution by iron porphyrin enzymes

1959 ◽  
Vol 12 (1) ◽  
pp. 47
Author(s):  
NK King ◽  
ME Winfield
Keyword(s):  
Ascorbic Acid ◽  
Carbon Atom ◽  
Oxygen Uptake ◽  
Cytochrome Oxidase ◽  
Metal Atom ◽  
Iron Porphyrin ◽  
Reduction Step ◽  
The Third ◽  
Catalase Peroxidase ◽  
Electron Deficiency

Three detailed mechanisms are considered for the catalatic decomposition of H2O2. It is shown that the first of these, akin to the earlier hypotheses for catalase action, cannot satisfy the magnetic, titrimetric, and kinetic evidence. The second mechanism involves oxidation of the FeIII porphyrin to the equivalent of FeV. The electron deficiency is distributed over the ligands so that even in the most oxidized complex the iron is in the FeIV or possibly even the FeIII state. In the third scheme it is suggested that the reduction step (in which O2 is liberated) takes place at a carbon atom, while the site of the oxidation is the metal atom as commonly supposed. The liberation of O2 from H2O2 can be catalysed by 6-coordinate ruthenium II complexes. In the catalytic cycle, the metal appears to be oxidized to Rdv, then reduced to RuII. Ethanol or ascorbic acid can substitute for H2O2 in the reduction. Evidence for H2O2 attack on the ligands is suggestive but not conclusive. A brief comment is made on the bonding of oxygen to haemoglobin and myoglobin. The accumulated evidence for the structures of catalase, peroxidase, and myoglobin complexes is utilized in a scheme for the uptake of oxygen by cytochrome oxidase.

Pseudohalogeno-Metallverbindungen, LXVIII [1]. Reaktionen der Cyanometallsäuren NCAuCNH, (NC)4Pt(CNH)2, (NC)2M(CNH)4(M = Fe, Ru, Os) und Co[bis(dimethyIglyoximato)](CN)CNHmit Epoxiden: 2-Hydroxyalkylisocyanid- und Oxazolidin-2-yIiden-MetalIkomplexe / Pseudohalogeno Metal Compounds, LXVIII [1]. Reaction of Cyano Metal Acids NCAuCNH, (NC)4Pt(CNH)2, (NC)2M(CNH)4 (M = Fe, Ru, Os) and Co[bis(dimethylglyoximato)](CN)CNH with Epoxides: 2-Hydroxyalkylisocyanide and Oxazolidine-2-ylidene Metal Complexes

1988 ◽  
Vol 43 (3) ◽  
pp. 328-338 ◽  
Author(s):  
Wolfgang Weigand ◽  
Ulrich Nagel ◽  
Wolfgang Beck
Keyword(s):  
Crystal Structure ◽  
Carbon Atom ◽  
Metal Complexes ◽  
Structure Determination ◽  
Ring Opening ◽  
Crystal Structure Determination ◽  
Carbene Ligands ◽  
Metal Compounds

NCAuCNH reacts with expoxides to give oxazolidine-2-ylidene (2) and 2-hydroxyalkyl complexes (3), respectively. Complexes with cyclic carbene ligands [XXX] (5) and [XXX] (7) are formed from the corresponding isocyanic metal compounds and oxiranes. 5b has been characterized by crystal structure determination. Ring opening of phenyloxirane occurs at the phenyl substituted carbon atom. (NC)2M(CNH)4 (M = Fe, Ru, Os) and oxirane yield mixtures of [XXX] and [XXX].

An atomic resolution study of a carbide phase in platinum

1992 ◽  
Vol 50 (1) ◽  
pp. 20-21
Author(s):  
M.J. Witcomb ◽  
M.A. O'Keefe ◽  
CJ. Echer ◽  
C. Nelson ◽  
J.H. Turner ◽  
...  
Keyword(s):  
Solid Solution ◽  
Carbon Atom ◽  
Carbide Phase ◽  
Structural Changes ◽  
Critical Role ◽  
Alloy System ◽  
Atomic Resolution ◽  
Excess Carbon ◽  
Interstitial Carbon ◽  
Resolution Study

Under normal circumstances, Pt dissolves only a very small amount of interstitial carbon in solid solution. Even so, an appropriate quench/age treatment leads to the formation of stable Pt2C {100} plate precipitates. Excess (quenched-in) vacancies play a critical role in the process by accommodating the volume and structural changes that accompany the transformation. This alloy system exhibits other interesting properties. Due to a large vacancy/carbon atom binding energy, Pt can absorb excess carbon at high temperatures in a carburizing atmosphere. In regions rich in carbon and vacancies, another carbide phase, Pt7C which undergoes an order-disorder reaction was formed. The present study of Pt carburized at 1160°C and aged at 515°C shows that other carbides in the PtxC series can be produced.

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