Redox reactions between halides and reducing metal complexes in non-aqueous solution. Part 1.—Derivatives of tetrakis(triphenyl phosphite)nickel(0)

1974 ◽  
Vol 70 (0) ◽  
pp. 330 ◽  
Author(s):  
Clement H. Bamford ◽  
Izumi Sakamoto
Keyword(s):  
Aqueous Solution ◽  
Metal Complexes ◽  
Redox Reactions ◽  
Triphenyl Phosphite ◽  
Derivatives Of

scholarly journals Evidence for catalytic dismutation of superoxide by cobalt(II) derivatives of bovine superoxide dismutase in aqueous solution as studied by pulse radiolysis

1982 ◽  
Vol 205 (1) ◽  
pp. 181-187 ◽  
Author(s):  
P O'Neill ◽  
E M Fielden ◽  
D Cocco ◽  
G Rotilio ◽  
L Calabrese
Keyword(s):  
Aqueous Solution ◽  
Superoxide Dismutase ◽  
Rate Constants ◽  
Redox Reactions ◽  
Pulse Radiolysis ◽  
Turnover Rate ◽  
Copper Site ◽  
Initial Interaction ◽  
Derivatives Of ◽  
Reaction Schemes

By using the technique of pulse radiolysis to generate O2-., it is demonstrated that Co(II) derivatives of bovine superoxide dismutase in which the copper alone and both the copper and zinc of the enzyme have been substituted by Co(II), resulting in (Co, Zn)- and (Co, Co)-proteins, are capable of catalytically dismutating O2-. with ‘turnover’ rate constants of 4.8×10(6) dm3.s-1.mol-1 and 3.1×10(6) dm3.s-1.mol-1 respectively. The activities of the proteins are independent of the pH (7.4-9.4) and are about three orders of magnitude less than that of the native (Cu, Zn)-protein. The rate constants for the initial interaction of O2-. with the Co-proteins were determined to be (1.5-1.6) X 10(9) dm3.s-1.mol-1; however, in the presence of phosphate, partial inhibition is apparent [k approximately (1.9-2.3) X 10(8) dm3.s-1.mol-1]. To account for the experimental observations, two reaction schemes are presented, involving initially either complex-formation or redox reactions between O2-. and Co(II). This is the first demonstration that substitution of a metal into the vacant copper site of (Cu, Zn)-protein results in proteins that retain superoxide dismutase activity.

New insights into the metal ion–peptide hydroxamate interactions: Metal complexes of primary hydroxamic acid derivatives of common dipeptides in aqueous solution

Polyhedron ◽  
2007 ◽  
Vol 26 (8) ◽  
pp. 1625-1633 ◽  
Author(s):  
Péter Buglyó ◽  
Eszter Márta Nagy ◽  
Etelka Farkas ◽  
Imre Sóvágó ◽  
Daniele Sanna ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Complexes ◽  
Metal Ion ◽  
Hydroxamic Acid ◽  
Derivatives Of ◽  
Hydroxamic Acid Derivatives

scholarly journals Neutron Scattering Techniques for Studying Metal Complexes in Aqueous Solution

ACS Omega ◽  
2021 ◽  
Author(s):  
Franco Scalambra ◽  
Silvia Imberti ◽  
Nicole Holzmann ◽  
Leonardo Bernasconi ◽  
Antonio Romerosa
Keyword(s):  
Aqueous Solution ◽  
Metal Complexes ◽  
Neutron Scattering

scholarly journals Quantum-Chemical Search for Keto Tautomers of Azulenols in Vacuo and Aqueous Solution

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 497
Author(s):  
Ewa D. Raczyńska
Keyword(s):  
Aqueous Solution ◽  
Quantum Chemical ◽  
Biologically Active ◽  
Deprotonation Reaction ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Scanty Information ◽  
Derivatives Of ◽  
Common Anion ◽  
Tautomeric Mixture

Keto-enol prototropic conversions for carbonyl compounds and phenols have been extensively studied, and many interesting review articles and even books appeared in the last 50 years. Quite a different situation takes place for derivatives of biologically active azulene, for which only scanty information on this phenomenon can be found in the literature. In this work, quantum-chemical studies have been undertaken for symmetrically and unsymmetrically substituted azulenols (constitutional isomers of naphthols). Stabilities of two enol (OH) rotamers and all possible keto (CH) tautomers have been analyzed in the gas phase {DFT(B3LYP)/6-311+G(d,p)} and also in aqueous solution {PCM(water)//DFT(B3LYP)/6-311+G(d,p)}. Contrary to naphthols, for which the keto forms can be neglected, at least one keto isomer (C1H, C2H, and/or C3H) contributes significantly to the tautomeric mixture of each azulenol to a higher degree in vacuo (non-polar environment) than in water (polar amphoteric solvent). The highest amounts of the CH forms have been found for 2- and 5-hydroxyazulenes, and the smallest ones for 1- and 6-hydroxy derivatives. The keto tautomer(s), together with the enol rotamers, can also participate in deprotonation reaction leading to a common anion and influence its acid-base properties. The strongest acidity in vacuo exhibits 6-hydroxyazulene, and the weakest one displays 1-hydroxyazulene, but all azulenols are stronger acids than phenol and naphthols. Bond length alternation in all DFT-optimized structures has been measured using the harmonic oscillator model of electron delocalization (HOMED) index. Generally, the HOMED values decrease for the keto tautomers, particularly for the ring containing the labile proton. Even for the keto tautomers possessing energetic parameters close to those of the enol isomers, the HOMED indices are low. However, some kind of parallelism exists for the keto forms between their relative energies and HOMEDs estimated for the entire molecules.

scholarly journals Functionalised Terpyridines and Their Metal Complexes—Solid-State Interactions

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 199-227
Author(s):  
Young Hoon Lee ◽  
Jee Young Kim ◽  
Sotaro Kusumoto ◽  
Hitomi Ohmagari ◽  
Miki Hasegawa ◽  
...  
Keyword(s):  
Solid State ◽  
Metal Complexes ◽  
Crystal Structures ◽  
Weak Interactions ◽  
Dispersion Interactions ◽  
Derivatives Of

Analysis of the weak interactions within the crystal structures of 33 complexes of various 4′-aromatic derivatives of 2,2′:6′,2″-terpyridine (tpy) shows that interactions that exceed dispersion are dominated, as expected, by cation⋯anion contacts but are associated with both ligand–ligand and ligand–solvent contacts, sometimes multicentred, in generally complicated arrays, probably largely determined by dispersion interactions between stacked aromatic units. With V(V) as the coordinating cation, there is evidence that the polarisation of the ligand results in an interaction exceeding dispersion at a carbon bound to nitrogen with oxygen or fluorine, an interaction unseen in the structures of M(II) (M = Fe, Co, Ni, Cu, Zn, Ru and Cd) complexes, except when 1,2,3-trimethoxyphenyl substituents are present in the 4′-tpy.

scholarly journals The Exchange of Cyclometalated Ligands

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 210
Author(s):  
Alexander D. Ryabov
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Cyclopalladated Complexes ◽  
Derivatives Of ◽  
Cyclometalated Ligand ◽  
Incoming Ligand

Reactions of cyclometalated compounds are numerous. This account is focused on one of such reactions, the exchange of cyclometalated ligands, a reaction between a cyclometalated compound and an incoming ligand that replaces a previously cyclometalated ligand to form a new metalacycle: + H-C*~Z ⇄ + H-C~Y. Originally discovered for PdII complexes with Y/Z = N, P, S, the exchange appeared to be a mechanistically challenging, simple, and convenient routine for the synthesis of cyclopalladated complexes. Over four decades it was expanded to cyclometalated derivatives of platinum, ruthenium, manganese, rhodium, and iridium. The exchange, which is also questionably referred to as transcyclometalation, offers attractive synthetic possibilities and assists in disclosing key mechanistic pathways associated with the C–H bond activation by transition metal complexes and C–M bond cleavage. Both synthetic and mechanistic aspects of the exchange are reviewed and discussed.

Pentaalkyl-Derivate des 2 ,3 - Dihiydro-1,3-diborols/Pentaalkyl Derivatives of the 2,3-Dihydro-1,3-diborole

1990 ◽  
Vol 45 (1) ◽  
pp. 15-18 ◽  
Author(s):  
G . Knörzer ◽  
W. Siebert
Keyword(s):  
Redox Reactions ◽  
Halogen Exchange ◽  
Derivatives Of

AbstractDouble hydroboration of acetylene, propyne-1 and t-butylacetylene with HBCl2 · OEt2/BCl3 leads to the 1,1-bis(dichloroboryl)alkanes 2d, e, f, in which halogen exchange is achieved by BI3 to give 3d, e, f. Redox reactions between butyne-2, hexyne-3 and 3 result in the formation of compounds 4, which are alkylated with AlMe3 and AlEt3 to give the pentaalkyl derivatives 1d, e, f. Reactions of 1 with [(C5H5)Co(C2H4)2] an [(C5H5)N iCO]2 lead to the complexes 5 and 6.

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