Secondary interactions - Cement in trinuclear calcium complexes

Sorin-Claudiu Rosca (1) , Vincent Dorcet (1) , Jean-François Carpentier (1) , Yann Sarazin (1)

1 ISCR - Institut des Sciences Chimiques de Rennes

The trinuclear calcium complex [Ca-3(mu(2)-{RO1})(2)(mu(2)-N(SiMe2H)(2))(2)(N(SiMe2H)(2))(2)] (2) was synthesised upon stoichiometric or substoichiometric reactions between [Ca[N(SiMe2H)(2)](2)center dot(THF)] and the aminoflu-oroalcohol CH2=CH-(CH2)(2)N(Bu-t)CH2C(CF3)(2)OH, {RO1}H. This unusual calcium cluster was characterised by X-ray diffraction crystallography. It contains bridging alkoxides and amides, and is stabilised by a remarkable pattern of intramolecular beta-Si-H center dot center dot center dot Ca agostic and C-F center dot center dot center dot Ca interactions which are amongst the shortest known to date. Bond valence sum analysis showed that far from being negligible, these secondary interactions amount to about 20% of the overall bonding pattern about the calcium atoms in 2. These results provide further evidence of the importance of non-covalent interactions in the coordination chemistry of alkaline earths, as a useful tool to design original molecular edifices.

Keywords: Calcium; Secondary interactions; Fluoroalkoxide; Agostic bonding; Calcium-fluorine interactions

Domains: Chemical Sciences; Coordination chemistry; Chemical Sciences; Inorganic chemistry

Sorin-Claudiu Rosca, Vincent Dorcet, Jean-François Carpentier, Yann Sarazin. Secondary interactions - Cement in trinuclear calcium complexes. Inorganica Chimica Acta, 2018, 475, pp.59-64. ⟨10.1016/j.ica.2017.08.038⟩. ⟨hal-01771100⟩