Organocalcium (Ca-C) σ-bond Containing Compounds

Compared to other organometallics, the number of organocalcium compounds and their related publications are limited. In this chapter, we grouped different Ca-Cσ-bond containing organocalcium compounds described in the literature, (Alkyl, silyl, cycloalkyl, benzyl, alkenyl, alkynyl, diene, diyne, phenyl, biphenyl, anthracene, halo thiophene and picoline derivatives) with the specificity for each kind of compounds. We discuss the stabilizing factors of structures including: conjugation, hyperconjugation, complexing heteroatom lone pairs and π-bonding electron pairs. The different synthetic processes used to avoid synthetic problems of substrate and calcium source reactivity, intermediate and product stability and solubility, reaction temperature, yields and decomposition reactions of both intermediates and products, as well as the orientation of the reaction sides in some reactions, are also grouped (thiophene and picoline derivatives). The halo aromatic organocalcium compounds are described to be the most stable intermediates, giving the best yields. Some calculations that correlate with experimental results are mentioned. Particular calcium reagents, such as Ca*, CaI2 and particular reactions as well as exchange (transmetalation) reactions are also examined. Some examples of the geometrical structures, which give C-Ca-C bent angles, and bond lengths obtained from X-ray are gathered.

Keywords: Activated calcium, Calcium complexes, Calcium coordination, Calcium derivatives, Calcium halides, Calcium halo intermediates, Calcium insertion reaction;, Calcium-Carbon bent angle, Calcium-Carbon σ-bond, Direct and indirect synthesis, Ethereal coordination, Ethereal medium, Exchange reaction, Ipso-carbon atom, Metathesis reaction, Organocalcium complex, Organocalcium degradation, Organylcalcium, Schlenk equilibrium, Transmetalation.