Ligands equilibria involving

Two equiv. of 6,6-di(cyclopropyl)fulvene react at 60 °C over a period of a week with Ca[N(SiMe3)2]2-(THF)2 bis in THF to yield the metallocene 170. The heteroleptic amido complex 171 is detected as an intermediate with 111 and 13C 1H NMR spectroscopy. A 1 1 reaction of the calcium amide and 170 also produces 171 in solution, an equilibrium involving these three derivatives exists (Equation (30)). The calcocene 170 crystallizes at — 20 °C from THF as colorless cuboids. The metal center is surrounded by the four ligands in a distorted tetrahedral manner, and the cyclopentadienyl group and the propylidene fragment are coplanar with each other.393... 

This equilibrium may be used to define an extraction constant (Kex) in the usual way. It should be noted that under some conditions, especially when larger ions are involved, a second equilibrium involving complexation of a further molecule of (non-deprotonated) ligand may also be present. 

Mo2(H20)8+ is one of only three dimeric aqua ions with no bridging ligands (Hgf and Rh are the others). The structure 5 is eclipsed with 6-bond formation and quadruple metal-metal bonding. A rapid pre-equilibrium involving substitution of anion into the axial (end) waters. 

An efficient and selective Cu-assisted ortho-hydroxylation procedure for the conversion of benzoate to salicylate has been described, involving trimethylamine N-oxide (TMAO) as the oxidant [191,192]. The reaction was assumed to proceed via oxidation of a Cu carboxylate complex by TMAO to produce the active species (postulated to be a Cu hydroxo complex, but with only circumstantial evidence), followed by oxygen transfer to the benzoate group (Scheme 14). Using a set of different amide derivatives of benzoic acid, Comba and co-workers gained additional mechanistic hints in support of a reactive Cu-oxo or Cu-hydroxo intermediate that is stabilized by a five-membered chelate [193]. A pre-equilibrium involving Cu the ligand, and TMAO was proposed, but details of the reaction are far from clear. 

Removal of metals by immobilized ligands frequently involves a choice of two techniques, a batch method or column chromatography. The batch method can be faster when samples are taken from the supernatant for replicate analyses. This method also can establish when equilibrium (or stasis) has been established. One flaw is that the sample of solid may not be... 

Hydrolysis of Pd(MeCOCHMe)2 in aqueous methanol is considered to involve Pd(0,0-MeCOCHCOMe)(0-MeCOCHCOMe)(MeOH) as an intermediate from which the monodentate acetylacetonate ligand is then solvolyzed.221 Subsequent studies on Lewis base complexes of palladium bis(diketonate) complexes provide ample support for the proposed intermediate. A pulse radiolysis study of the kinetics of aquation of M(MeCOCHCOMe) " (M = Cr, Co) indicates that an 17,-172 equilibrium involving one or more of the acetylacetonate ligands occurs, associated with an acid-catalyzed removal of the monodentate ligand.222 Treatment of Cu(MeCOCHCOMe)2 with picric acid in moist dichloromethane affords a partially hydrolyzed material, Cu(MeCOCHC-0Me)(H20)2[C6H2(N02)30], proposed to contain square pyramidal five-coordinate copper with the oxygen atom from the picrate moiety at the apex.223... 

Inhibitors are often included in formulations to increase the pot life and cure temperature so that coatings or moldings can be conveniendy prepared. An ideal silicone addition cure may combine instant cure at elevated temperature with infinite pot life at ambient conditions. Unfortunately, real systems always deviate from this ideal situation. A proposed mechanism for inhibitor (I) function is an equilibrium involving the inhibitor, catalyst ligands (L), the silicone—hydride groups, and the silicone vinyl groups (177). 

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