Uranium rhodium bonding in heterometallic complexes† †Electronic supplementary information (ESI) available. CCDC 1519919–1519921. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6dt04570g Click here for additional data file. Click here for additional data file.

The heterotetra- and bimetallic uranium(iv)-rhodium(i) complexes [UIVI2(μ-OArP-1κ1O,2κ1P)2RhI(μ-I)]2 (2) (ArPO- = 2-(diphenylphosphino)-6-tert-butyl-4-methylphenoxide) and UIVI(μ-I)(μ-OArP-1κ1O,2κ1P)3RhI (3) were prepared by treatment of UIVI(OArP-κ2O,P)3 (1) with rhodium(i) iodide olefin complexes. The reaction of 1 with the monodentate cyclooctene (coe) rhodium(i) precursor [(coe)2RhII]2 gives only the bimetallic complex [UIVRhI] 3, and with the diene [(cod)RhII]2 (5) (cod = 1,5-cyclooctadiene), mixtures of [UIVRhI]2 complex 2 and [UIVRhI] 3 along with (cod)RhIOArP-κ2O,P (4), a RhI side-product from the formation of 2. The complexes were characterised by single crystal X-ray diffraction, NMR and UV-vis-NIR spectroscopy, and electrochemistry. The UIV-RhI intermetallic distances in 2 (2.7601(5) Å) and 3 (2.7630(5) Å) are among the shortest between f-elements and transition metals reported to date. Despite almost identical U-Rh bond lengths in the solid state, in solution only weak, and very different interactions between the metal centres are found.