A new robust and high-yielding synthesis of the valuable U-III synthon [U(BH4)(3)(THF)(2)] is reported. Reactivity in ligand exchange reactions is found to contrast significantly to that of uranium triiodide. This is exemplified by the synthesis and characterization of azamacrocyclic U-III complexes, including mononuclear [U(BH4)(L)] and dinuclear [Li(THF)(4)][{U(BH4)}(2)(mu-BH4)(L-me)] and [Na(THF)(4)][{U(BH4)}(2)(mu-BH4)(L-A)-(THF)(2)]. The structures of all complexes have been determined by single-crystal X-ray diffraction and display two new U-2(III)(BH4)(3) motifs.