We recently reported the formation of a bridging carbonate complex [{(((ArO)-Ar-Ad)(3)N)U}(2)(mu-eta(1):kappa(2)-CO3)] via reductive cleavage of CO2, yielding mu-oxo bridged complex, followed by the insertion of another molecule of CO2. In a similar strategy, we were able to isolate and characterize a series of mixed carbonate complexes U-CO2E-U, U-CS2E-U, and even U-OC(S)Se-U, by reacting bridged chalcogenide complexes [{(((ArO)-Ar-Ad)(3)N)U}(2)(mu-E)] (E = S, Se) with CO2, CS2, and COS. These chalcogenido mixed-carbonate complexes represent the first of their kind.