Carbon Dioxide Capture and Functionalization from a Molecular Ti(III) Oxo Anion

Carbon dioxide capture and functionalization sequesters carbon dioxide in more robust products and offers a viable route to reducing greenhouse gas emissions. We present herein a unique molecular Ti III oxo anion that reversibly binds CO 2 to allow both its sequestration and functionalization. The reduction of [(PN) 2 Ti═O] ( 1 ) [PN = (2‐P i i Pr 2 ‐4‐methylphenyl)(mesityl)amide] with KC 8 and 2.2.2‐cryptand (crypt) resulted in formation of [K(crypt)][(PN) 2 Ti═O] ( 2 ), which was fully characterized and shown to contain a Ti‐centered radical. Complex 2 reacts with Al(CH 3 ) 3 to form [K(crypt)][(PN) 2 Ti{O(Al(CH 3 ) 3 }] ( 3 ), which can be independently prepared from [K(crypt)][(PN) 2 Ti(OCP)] and Al(CH 3 ) 3 . Whereas 1 does not react with CO 2 , 2 rapidly captures the gas (1 atm, 25 °C) to produce a Ti III carbonate [K(crypt)][(PN) 2 Ti(κ 2 ‐O 2 C═O)] ( 4 ). Chemical and electrochemical oxidation of 4 releases CO 2 to regenerate 1 while a soluble organic carbonate [Me 3 SiOC(O)OSiMe 3 , Me = CH 3 ] is obtained from reaction of 4 with ClSiMe 3 .