Synthesis of Phospholyltetrahydroboratouranium Complexes. Crystal Structure of [(η5‐C4Me4P)2U(BH4)2]

P-NMR chemical shifts of δ = 3471(!) and δ = 227 reflect the unusual bonding situation in the dimeric, paramagnetic organouranium(III) complex 1. The signal shifted extremely downfield can be assigned to the P atom of the bridging phospholyl ligand. 1 can be oxidized with TlBH4 to the uranium(IV) sand-°Ch [(C4Me4P)2U(BH4)2], which on reduction with Na-amalgam forms 1 again.