A Heterodimetallic Monomeric Complex with a Uranium–Cobalt Triple Bond

Abstract The crystal structure of heterodimetallic monomeric complexes featuring a U–M triple bond has been rarely reported. Here, we present an example of a heterodimetallic monomeric complex [(Trapen CH2PPh2 )U(Co)] ( 4 ) containing a U–Co triple bond, which was synthesized by the reaction of [(Trapen CH2PPh2 )U(Cl)] ( 2 ) or [(Trapen CH2PPh2 )U] ( 3 ) with CoCl 2 in the presence of KC 8 . The crystal structure of 4 reveals a highly symmetrical geometry with a linear Co–U–N amine axis line, and the U–Co bond length 2.1890(11) Å is slightly longer than the sum of the covalent triple‐bond radii of uranium and cobalt (2.14 Å). The U–N amine bond length (2.439(6) Å) is significantly shortened compared to that of precursors 2 and 3 . The significant contraction of the U–N amine bond demonstrates electronic reinforcement via the inverse trans‐influence (ITI). Detailed computational investigations further support the existence of a U≡Co triple bond in 4 , and the formal oxidation states of uranium and cobalt appear to be U(IV) and Co(‐I). The low‐temperature magnetic moments of 4 are approaching 2.1 μ B , which is attributed to its near‐doubly degenerate spin‐orbit ground states in the pseudo‐C 3v symmetry. Remarkably, 4 served as the catalyst for the hydroboration and dimerization of terminal alkynes under mild conditions.