Complexes of aluminum

It has been suggested that alkene or alkyne complexes are mechanistically important intermediates in hydroalumination and carboalumination reactions (124-126). Clear spectroscopic evidence for n interactions stems from investigations of alkenylaluminum compounds having a suitable intramolecular separation between the aluminum center and the double bond (127). IR and NMR data of these compounds show comparably lower alkene stretching frequencies and deshielded vinylic protons. Furthermore, these molecules are monomeric in solution this indicates that the tendency toward 7i-complex formation is stronger than that toward the dimeric bonding usual in aluminum alkyls. 

The known dialkyl(cyclopentadienyl)aluminum compounds are all highly fluxional 124,133) IR and NMR data are therefore not conclusive evidence for their ground-state structures. We restrict ourselves to those compounds where X-ray crystal structure or gas phase electron diffraction data are available. 

Compound XXXVI undergoes thermal rearrangement in the vapor phase at 410°C to the isomer XXXVII in high yield (141). When XXXVI is dissolved in TFIF the crystalline complex EtAlC2H2B9H9-2THF (XXXVIII) is obtained. 

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Destruction of the masking ligand by chemical reaction may be possible, as in the oxidation of EDTA in acid solutions by permanganate or another strong oxidizing agent. Hydrogen peroxide and Cu(II) ion destroy the tartrate complex of aluminum. 

The Complexity of Aluminum-DNA Interactions Relevance to Alzheimer s and Other Neurological Diseases... 

The colors of flowering plants such as hydrangeas are highly sensitive to soil acidity. At pH > 6.5, these showy flowers are deep pink, but at pH < 5, the blossoms are vivid blue. The chemistry of these changes involves complexation of aluminum by pigments that have acidic groups, as the structures show. 

Complexes of tetravalent zirconium with organic acids, such as citric, tartaric, malic, and lactic acids, and a complex of aluminum and citric acid have been claimed to be active as dispersants. The dispersant is especially useful in dispersing bentonite suspensions [288]. Polymers with amine sulfide terminal moieties are synthesized by using aminethiols as chain transfer agents in aqueous addition polymerizations. The polymers are useful as mineral dispersants [1182]. 

Groups attached to aluminum or boron in this way have the expected increased electrophilic and decreased nucleophilic reactivities. For example, the complex of aluminum triphenyl and phenyl lithium lacks the usual Grignard-like reactivity of phenyl lithium towards-carbonyl compounds.800... 

Figure 17 Bimetallic ferrocene and nickelocene complexes of aluminum. 

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