Preparation, Structure, and Ether Cleavage of a Mixed Hapticity Allyl Compound of Calcium

• Published in: Organometallics Vol. 30; no. 19; pp. 5291 - 5296
• Main Authors: Jochmann, Phillip, Spaniol, Thomas P, Chmely, Stephen C, Hanusa, Timothy P, Okuda, Jun
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10.10.2011
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om200749f

The synthesis, characterization, and decomposition pathway of the 18-crown-6 adduct of bis(allyl)calcium [Ca(η1-C3H5)(η3-C3H5)(18-crown-6)] (2) are reported. The solid-state structure of adduct 2 features one σ- and one π-bonded allyl ligand at the metal center. 2 is the first structurally characterized example of a mononuclear calcium complex bearing a purely σ-bound allyl ligand. DFT calculations indicate that [Ca(η1-C3H5)(η3-C3H5)(18-crown-6)] and [Ca(η1-C3H5)2(18-crown-6)] conformations are close in energy. In THF solution, η3-allyl ligands are observed exclusively at both ambient temperature and −95 °C. 2 undergoes rapid cleavage of the crown ether to give vinyl-terminated alcoholates of different chain length with a half-life of t 1/2 = 2.5 h.