Coordination, Degrading Agent, Catalyst Property and Spectroscopy of Organocalcium Compounds

Résumé fourni par la source

In addition to the coordination of the calcium to the n electron pairs, some examples of coordination to the π electron pairs are observed resulting from calcium interactions with highly conjugated systems. The complex structures vary from ordinary to close to the unexpected organocalcium inverse sandwich. The organocalcium Ca-C bond containing compounds are highly reactive. They degrade and act as degrading agents on the solvent. The study of the effect of five factors: temperature, concentration, organic group, counter ion and coordinated donor solvent, shows an intramolecular degradation mechanism. Organocalcium complexes are more stable in the THP than in the THF ethereal media. Calcium and organocalcium Ca-Cσ-bond containing derivatives are described as efficient pre-catalysts for catalytic conversions of alkenes by polymerization, hydroamination, hydrosilylation, hydrogenation, and hydrophosphination. The activation process is suggested as an electrostatic interaction between the alkene and Lewis acidic calcium metallic species, leading to both vertical and horizontal polarization of the π bond electron density, resulting in an incentive for nucleophilic attack. Some researchers illustrate that the organocalcium derivatives may be described as “Trojan horses” X-ray constitutes the most efficient technique to characterize the organocalcium structures for crystalized compounds, affording interesting information about angle values and bond lengths. The 43Ca, 13C and 1H NMR spectroscopy constitutes an alternative, secondary and complementary tool for characterizing both soluble, and even insoluble compounds, monitoring the reaction progress and making specific experimental manipulations. The coupling constants 1 JCa-C, and 2 JCa-C-H are not mentioned and there is no mass spectrometry nor IR spectroscopy studies

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