Insertion of Carbon Dioxide into Main‐Group Complexes: Formation of the [N(CO 2 ) 3 ] 3− Ligand

Under mild conditions CO 2 reacts with [Sr{N(PPh 2 ) 2 } 2 ](THF) 3 to oxidatively cleave PPh 2 groups, resulting in the new ligand [N(CO 2 ) 3 ] 3− in [Sr 6 {O 2 CN(PPh 2 ) 2 } 6 {N(CO 2 ) 3 } 2 ] (see core structure; Sr green, O red, N blue, C black). The Sr 6 framework chemically fixates twelve equivalents of CO 2 , half by the formation of two [N(CO 2 ) 3 ] 3− ligands and the other half by CO 2 insertion to form the unprecedented phosphanyl‐substituted carbamate ligand O 2 CN(PPh 2 ) 2 .