Reversible Uptake of CO₂by Pincer Ligand Supported Dimetallynes

Abstract

We report on the reversible uptake of carbon dioxide by dimetallynes featuring ancillary hemi-labile pincer ligands. Insertion into the GeÀ Ge/SnÀ Sn bonds yields species containing an E(CO 2 )E unit, with the mode of ligation of the CO 2 fragment determined crystallographically being found to be dependent on the identity of the Group 14 element. The thermodynamics of CO 2 uptake/loss can be established through VT NMR (ΔH°= + 24.6(2.3) kJ mol À 1 , ΔS°= + 64.9(3.8) J mol À 1 K À 1 , ΔG°2 98 = + 5.3(1.9) kJ mol À 1 for the loss of CO 2 in the Ge case), and the chemical consequences of reversibility demonstrated by thermodynamically-controlled exchange reactions.