Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex Ross F. Koby1, Nicholas R. Rightmire1, Nathan D. Schley1, Timothy P. Hanusa*1 and William W. Brennessel2 Full Research Paper Open Access Address: Beilstein J. Org. Chem. 2019, 15, 1856–1863. 1Department of Chemistry, Vanderbilt University, PO Box 1822, doi:10.3762/bjoc.15.181 Nashville, TN 37235, USA and 2X-ray Crystallographic Facility, B51 Hutchison Hall, Department of Chemistry, University of Rochester, Received: 01 March 2019 Rochester, NY 14627, USA Accepted: 18 July 2019 Published: 02 August 2019 Email: Timothy P. Hanusa* -
[email protected] This article is part of the thematic issue "Mechanochemistry II". * Corresponding author Guest Editor: J. G. Hernández Keywords: © 2019 Koby et al.; licensee Beilstein-Institut. caesium; entropy; intermolecular forces; mechanochemistry; License and terms: see end of document. metathesis; potassium Abstract As a synthesis technique, halide metathesis (n RM + M'Xn → RnM' + n MX) normally relies for its effectiveness on the favorable formation of a metal halide byproduct (MX), often aided by solubility equilibria in solution. Owing to the lack of significant thermodynamic driving forces, intra-alkali metal exchange is one of the most challenging metathetical exchanges to attempt, espe- cially when conducted without solvent. Nevertheless, grinding together the bulky potassium allyl [KA']∞ (A' = [1,3- – (SiMe3)2C3H3] ) and CsI produces the heterometallic complex [CsKA'2]∞ in low yield, which was crystallographically character- ized as a coordination polymer that displays site disorder of the K+ and Cs+ ions. The entropic benefits of mixed Cs/K metal … … centers, but more importantly, the generation of multiple intermolecular K CH3 and Cs CH3 interactions in [CsKA'2]∞, enable an otherwise unfavorable halide metathesis to proceed with mechanochemical assistance.