Inverse cycloheptatrienyl sandwich complexes of uranium and neodymium

Reaction of UX 4 (X = NEt 2 or BH 4 ) with K[C 7 H 9 ] afforded the anionic complexes K[X 3 U(µ-η 7 ∶η 7 -C 7 H 7 )UX 3 ] whereas treatment of [Nd(BH 4 ) 3 (thf) 2 ] (thf = tetrahydrofuran) with K[C 7 H 9 ] gave the neutral compound [(thf)(BH 4 ) 2 Nd(µ-η 7 ∶η 7 -C 7 H 7 )Nd(BH 4 )(thf) 2 ]. The formation of the cycloheptatrienyl ligand resulted from the disproportionation reaction 3 C 7 H 9 - → C 7 H 7 3- + 2 C 7 H 10 . The crystal structure of [(thf)(BH 4 ) 2 Nd(µ-η 7 ∶η 7 -C 7 H 7 )Nd(BH 4 )(thf) 3 ], the first cycloheptatrienyl compound of a 4f element, has been determined.