Crystalline Diuranium Phosphinidiide and μ‐Phosphido Complexes with Symmetric and Asymmetric UPU Cores

Reaction of [U(Tren TIPS )(PH 2 )] ( 1 , Tren TIPS =N(CH 2 CH 2 NSiPr i 3 ) 3 ) with C 6 H 5 CH 2 K and [U(Tren TIPS )(THF)][BPh 4 ] ( 2 ) afforded a rare diuranium parent phosphinidiide complex [{U(Tren TIPS )} 2 (μ‐PH)] ( 3 ). Treatment of 3 with C 6 H 5 CH 2 K and two equivalents of benzo‐15‐crown‐5 ether (B15C5) gave the diuranium μ‐phosphido complex [{U(Tren TIPS )} 2 (μ‐P)][K(B15C5) 2 ] ( 4 ). Alternatively, reaction of [U(Tren TIPS )(PH)][Na(12C4) 2 ] ( 5 , 12C4=12‐crown‐4 ether) with [U{N(CH 2 CH 2 NSiMe 2 Bu t ) 2 CH 2 CH 2 NSi(Me)(CH 2 )(Bu t )}] ( 6 ) produced the diuranium μ‐phosphido complex [{U(Tren TIPS )}(μ‐P){U(Tren DMBS )}][Na(12C4) 2 ] [ 7 , Tren DMBS =N(CH 2 CH 2 NSiMe 2 Bu t ) 3 ]. Compounds 4 and 7 are unprecedented examples of uranium phosphido complexes outside of matrix isolation studies, and they rapidly decompose in solution underscoring the paucity of uranium phosphido complexes. Interestingly, 4 and 7 feature symmetric and asymmetric UPU cores, respectively, reflecting their differing steric profiles.