Beryllium complex chemistry

Chemistry of beryllium-m-oxoacetato complexes. A. I. Grigoriev and V. A. Sipachev, Inorg. Chim. Acta, 1976,16, 269-279 (55). 

What makes beryllium so special is the fact that in aqueous solution its cation, Be2+, is the only cation that is both habitually 4-coordinate and forms a range of complexes with simple ligands. This means that an understanding of the chemistry of this cation should... 

Halides other than fluoride form very weak complexes in aqueous solution there are no reliable equilibrium constants to be found in the literature. The solution chemistry of aqueous solutions of beryllium chloride, bromide, and iodide have been reviewed previously (9). Some evidence for the formation of thiocyanate complexes was obtained in solvent extraction studies (134). 

One of the surprising aspects of this and other studies using naked metal ions as models for electron-transfer catalysis are the many analogies found to known transition metal chemistry, either in the gas phase with naked ions or for complexes under more normal conditions. Clearly, such simple models as the beryllium cation cannot account for transition metal reactivity, but they do have the advantage that, because of their very simplicity, the reasons for their effects are relatively clear. The fact that Be can catalyze a given reaction does not necessarily mean that, for instance, a transition metal does not use d-orbitals to catalyze the same reaction but it does mean that d-orbitals are not a prerequi-... 

The study of coordination compounds of the lanthanides dates in any practical sense from around 1950, the period when ion-exchange methods were successfully applied to the problem of the separation of the individual lanthanides,131-133 a problem which had existed since 1794 when J. Gadolin prepared mixed rare earths from gadolinite, a lanthanide iron beryllium silicate. Until 1950, separation of the pure lanthanides had depended on tedious and inefficient multiple crystallizations or precipitations, which effectively prevented research on the chemical properties of the individual elements through lack of availability. However, well before 1950, many principal features of lanthanide chemistry were clearly recognized, such as the predominant trivalent state with some examples of divalency and tetravalency, ready formation of hydrated ions and their oxy salts, formation of complex halides,134 and the line-like nature of lanthanide spectra.135... 

Benzyl complexes metal hydroxides chemistry, 358 a-monooxime, 272 Benzylideneimine Schiff bases metal complexes, 721 Beryllium, alkylalkoxy synthesis, 340 ... 

Density functional theory studies arene chromium tricarbonyls, 5, 255 beryllium monocyclopentadienyls, 2, 75 chromium carbonyls, 5, 228 in computational chemistry, 1, 663 Cp-amido titanium complexes, 4, 464—465 diiron carbonyl complexes, 6, 222 manganese carbonyls, 5, 763 molybdenum hexacarbonyl, 5, 392 and multiconfiguration techniques, 1, 649 neutral, cationic, anionic chromium carbonyls, 5, 203-204 nickel rj2-alkene complexes, 8, 134—135 palladium NHC complexes, 8, 234 Deoxygenative coupling, carbonyls to olefins, 11, 40 (+)-4,5-Deoxyneodolabelline, via ring-closing diene metathesis, 11, 219... 

Beryllium chemistry includes its S-diketonate complexes formed from dimedone (9), acetylacetone and some other S-diketones such as a,a,a-trifluoroacetylacetone. However, unlike the monomeric chelate products from acetylacetone and its fluorinated derivative, the enolate species of dimedone (9) cannot form chelates and as the complex is polymeric, it cannot be distilled and is more labile to hydrolysis, as might be expected for an unstabilized alkoxide. However, dimedone has a gas phase deprotonation enthalpy of 1418 9 kJmoD while acetylacetone enol (the more stable tautomer) is somewhat less acidic with a deprotonation enthalpy of 1438 10 klmoD Accordingly, had beryllium acetylacetonate not been a chelate, this species would have been more, not less, susceptible to hydrolysis. There is a formal similarity (roughly 7r-isoelectronic structures) between cyclic S-diketonates and complexes of dimedone with benzene and poly acetylene (10). The difference between the enthalpies of formation of these hydrocarbons is ca... 

One of the most versatile classes of ligands in coordination chemistry is that of the /3-diketonates, of which the most common is the acetylacetonate, (acac), Figure 9.1. The coordination chemistry of this ligand first appears in the literature in work by Combes in 1887-1894. Alfred Werner also published on the chemistry of the acac ligand in 1901. The acac ligand is remarkable in that it forms complexes with virtually any metal, including beryllium, lead, aluminum, chromium, platinum, and gadolinium. 

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