Synthesis of (O2CEPh)1- Ligands (E = S, Se) by CO2 Insertion into Lanthanide Chalcogen Bonds and Their Utility in Forming Crystallographically Characterizable Organoaluminum Complexes [Me2Al(μ-O2CEPh)]2

CO2 inserts into the Sm−S and Sm−Se bonds of [(C5Me5)2Sm(μ-EPh)]2 (E = S, Se) to form the first crystallographically characterized (O2CEPh)1- complexes, [(C5Me5)2Sm(μ-O2CEPh)]2. These complexes are structurally analogous to [(C5Me5)2Sm(μ-O2CR)]2 complexes, but they are less soluble. This feature was utilized in the reaction of Me2AlCl with [(C5Me5)2Sm(μ-O2CEPh)]2, which forms crystallographically characterizable [Me2Al(μ-O2CEPh)]2 complexes. Such complexes could not be isolated from an analogous carboxylate reaction. [(C5Me5)2Sm(μ-O2CSePh)]2 decarboxylates in THF to form (C5Me5)2Sm(SePh)(THF). The loss of CO2 rather than COSe with formation of (C5Me5)2Sm(OPh)(THF) was established by 13CO2 studies and independent synthesis of (C5Me5)2Sm(OPh)(THF) from (C5Me5)2Sm[N(SiMe3)2] and PhOH.