Ligand, additivity exchange

Preparations from Other Organocobalt III) Compounds a. Addition, Exchange, or Removal of an Axial Ligand. This reaction is frequently used to prepare organocobalt(III) complexes with different ligands (usually neutral bases) in the sixth coordination position. The... 

Dissociation of a ligand from a complex may be spontaneous, acid-catalyzed, or consequent on the addition of an appropriate metal ion or ligand. Metal exchange, viz. ML+M ->M L+M, involves either dissociation of a complex (ML M+L) followed by formation of a new complex (M +L M L), or reaction through a... 

One must bear in mind that if the initial complex would be able to exchange more than one ligand molecule to give rise to M(L ) 2(L2)2, M(L ) 3(L2)3, and so on, the cyclic voltammogram would display a number of reduction peaks in addition to the more cathodic one shown in Figure 29b, equal to the further number of ligand molecules exchanged. 

In this case, it is believed that the tricycloalkylphosphine gel modification additive exchanges with the triphenyl phosphine ligands leading to a more active catalyst. The situation is reverse from the case discussed before. However, even when the catalyst becomes more active, as the concentration of gel modification additive is increased, the additive will compete with the monomer for coordination sites on the metal center and the additive may eventually act to decrease the rate of reaction. 

In [1677] complex alkoxides and alkoxide-carboxylates were compared as precursors for preparation ofBST films. In contrast to the introduction of alkaline earth carboxylates in the form of preliminary isolated salts, in this work metal alkoxide solution in methoxyethanol containing titanium and alkaline-earth metal was modified by addition of 2-ethylhexanoic acid with subsequent slow distilling off the solvent and repeated dilutions with fresh portions of methoxyethanol. During the distillation process, part of the alkoxide groups are substituted by the 2-ethylhexanoate ligands. The exchange reaction of Ti(OPr )4 with acid was studied in different solvents, and it was demonstrated that in the course of distillation the titanium oxoisopropoxy-2-ethylhexanoate is formed with elimination of ester ... 

Cyclohexane is oxygenated into cyclohexanone as the major product,[94] pointing to the occurrence of Mn-oxo type catalysis. HC1 treatment of the zeolite prior to ion exchange and ligand addition, shows a 4-fold increase in TOF, indicating that creation of mesopores with access to the external crystal rim enhances mass transfer without affecting the specific zeolitic sites needed for complex retention.1951... 

The dynamic behavior of tris-chelates was of considerable interest due to the additional constraint of a third bidentate ligand, relative to the extensively studied bis-chelates, with two monodentate ligands (Section III.A.3). Also the question of whether N-Si dissociation takes place during multi-step ligand-site exchange processes was considered. 

Triethylamine easily deprotonates the ring. The deprotio metalla-cyclobutadienes are more easily isolated after addition of pyridine ligands. Deuterium exchange on the p carbon of W(C3-/-Bu2D)[OCH(Cp3)2]3 with HOCH(Cp3)2 was demonstrated. Proton exchange probably occurs via elimination of DOCH(Cp3)2 and readdition of HOCH(Cp3)2. Even the presence of dimethoxymethane causes the elimination of HOCH(Cp3)2 [Eq. (206)]. In this case an equilibrium between the metallacyclobutadiene and its deprotonated counterpart could be observed. Por the phenyl-sub-... 

For the H2 ligand, additional solution dynamics can include equilibrium dissociation of H2, equilibria between i/2-H2-dihydride tautomers, ligand exchange via trihydrogen-like structures, and rotational motion of ij2-H2 (Scheme 1). The first... 

The stereochemistry of the reaction products of Scheme 7 again suggests that these reactions involve single-metal additions preceded by dihydrogen coordination to equatorial positions. In this respect, it has been shown that complex 9 can readily dissociate its acetonitrile ligands, and exchange them from axial to equatorial positions with low kinetic barriers.[28] Such vacancy rearrangements... 

Some alkyldiazenido complexes of nickel, palladium, molybdenum, and ruthenium were obtained by ligand exchange or by ligand addition. They were later demonstrated not to have end-on structures, but a side-on (t ) coordination at both diazo N-atoms. Itsuka and coworkers demonstrated that in bis( r butylisocyanide)... 

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