Mechanistic studies on the reductive cyclooligomerisation of CO by U(III) mixed sandwich complexes;: the molecular structure of [(U(η-C8H6{SiiPr3-1,4}2)(η-Cp*)]2(μ-η1:η1-C2O2)

The stoichiometric reaction of 1 equiv of CO with [(U(eta-C(8)H(6){Si(i)Pr(3)-1,4}(2)) (eta-Cp(*))] affords the linear diuranium ynediolate complex [(U(eta-C(8)H(6){Si(i)Pr(3)-1,4}(2)(eta-Cp(*))](2)(mu-eta(1):eta(1)-C(2)O(2)) which does not react with further CO to give the deltate derivative [(U(eta-C(8)H(6){Si(i)Pr(3)-1,4}(2))(eta-Cp(*))](2)(mu-eta(1):eta(2)-C(3)O(3)). Spectroscopic and computational studies suggest a plausible mechanism for the formation of the deltate complex, in which a zig-zag diuranium ynediolate species is the key intermediate.