Ligand-replacement reactions

The adducts B10H12L2 (structure 40) can be prepared by direct reaction of B10H14 with L or by ligand replacement reactions ... 

The molecule has an almost linear N3 group and an angle C-N-N of 112.4° (Fig. II.4a).( ) The (linear) azide ion, N3", is isoelectronic with N2O, CO2, OCN", etc. and forms numerous coordination complexes by standard ligand replacement reactions. Various coordination modes have been established, including end-on bridging... 

Reduction of the pH of solutions of carbonylate anions yields a variety of protonated species and, from acid solutions, carbonyl hydrides such as the unstable, gaseous H2Fe(CO)4 and the polymeric liquids H2Fe2(CO)g and H2Fe3(CO)n are liberated. The use of ligand-replacement reactions to yield hydrides of higher nuclearity has already been noted. 

The argument against Scheme 1 is a negative one. Its basis derives from extensive studies carried out on the ligand replacement reactions of oxorhenium complexes of the family MeReO(dithiolate)L (20,34-37). Those studies (Sections V.B and V.C) show that all such processes studied to date proceed by direct displacement reactions without a recognizable intermediate from unassisted Re-L dissociation. (Indeed, in an early work, a dissociative step was written, but that formulation has since been revised see Section V.D.)... 

The thermochemistry of the ligand replacement reaction 10.10, where pip indicates piperidine, was investigated by Adamson s group, using cyclohexane as solvent [183]. 

Ligand replacement reactions, which have been little studied, are strongly associative, as with other square-planar complexes. Replacement, as the first step in oxidative addition, has been detected by ir and conductivity monitoring in the reaction ... 

Investigations continue of ligand replacement reactions of the two coordinated solvent molecules of iron(II) phthalocyanine, (154), in It has been confirmed that both steps can be... 

Several synthetic procedures have been developed for the preparation of complexes with phosphines, arsines and stibines, and the most convenient or historically important ones are summarized in Table 3. They can be grouped in three main types of reaction the direct reactions of nickel with ligands, ligand replacement reactions and reduction reactions of nickel(H) complexes. 

Nickclocene. on the tuber hantl. is more slowly oxidized and undergoes addition ot suitable activated olefins to one ring convening it to a bicyclic ligand. Sumc ligand replacement reactions arc also known for nickclnccne. 

It has already been stated that chromium complexes of tridentate metallizable azo compounds occupy their position as the single most important class of metal complex dyestuffs because of their high stability. It should be noted, however, that in this context the term stability is not used in the thermodynamic sense but relates to the kinetic inertness of the complexes.25 Octahedral chromium(III) complexes have a tP electronic configuration and the ligand field stabilization energy associated with this is high.26 Ligand replacement reactions involve either a dissociative... 

Kinetics and Mechanisms of Ligand Replacement Reactions in Trigonal Bipyramidal Nickel(II) Complexes of a Tetradentate Ligand Containing an Apical Phosphorus Donor Atom... 

The cycloaurated benzyl bipyridine complexes 112 114 undergo ligand replacement reactions of the chloride ligand with a wide range of C-, N-, O- and S-donor... 

The oxidation state +3 is readily accessible via ligand replacement reactions on UI3(L) [L = tetrahydrofuran (thf), 1,2-dimethoxyethane (dme), pyridine (py)] (15), which in turn can be conveniently prepared by direct oxidation of U turnings with I2 in either THF or DME. Subsequent exchange of coordinated solvent with pyridine or acetonitrile can be accomplished via simple exposure to... 

From these many other MX4L2 complexes may be obtained by ligand replacement reactions. In some cases coordination number 7 is reached, as in the MCl4(PMe2Ph)3 complexes. 

For molybdenum(III), the MoCyU complexes with L = THF or RCN are useful reactants, as is also MoI3(THF)3. These molecules have meridional structures and readily undergo ligand replacement reactions with phosphines. 

The vast majority of ligand-replacement reactions fit into this category. Most conform to a simple two-term rate law of Eq. (1) ... 

Despite the long-standing and overwhelming dominance of associative pathways in ligand replacement reactions at square-planar mole-... 

The possible assistance given to leaving groups by electrophiles in the form of solvent or metal ions represents one part of a ligand replacement reaction normally referred to as SE2(cyclic). Structure 19 shows the interaction at the transition state. It can be seen as simultaneous attack of the electrophile E at the leaving group X and of the... 

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