Abstract
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 1JCa-C, and 2JCa-C-H are not mentioned and there is no mass
spectrometry nor IR spectroscopy studies
Keywords: Calcium ether cleavage THF, Degradation mechanism, Durability in ethereal solutions, Ether degradation, Hydroamination, Hydrosilylation, IpsoCarbon atom, Lewis acid, Mixture titration, NMR reaction monitoring, NMR spectroscopy, Organocalcium catalyst, Organocalcium inverse sandwich complex, π-Bond calcium coordination, π-Bond polarization, Polymerization reaction, THF degradation, THF α-deprotonation, Trojan horses, X-ray
