Cyclopentadienyl Ring Metathesis with Organocalcium and Organopotassium Compounds

Cyclopentadienyl ring metathesis occurs between [Ca(C 5 Me 5 ) 2 ] and [Ln(C 5 H 5 ) 3 ] complexes in toluene to generate the mixed ring compounds [Ln(C 5 Me 5 ) 2 (C 2 H 5 )] (Ln 1 ‐La, 1 ‐Nd). 1 ‐Nd has been characterized with X‐ray diffraction as a sterically crowded monomer. Only one ring is exchanged between [Ca(C 5 Me 5 ) 2 (thf) x ] and [La(C 5 H 5 ) 3 (thf) x ] in toluene to yield [La(C 5 Me 5 )C 5 H 5 ) 2 (thf)] ( 2 ). In reaction with [M(C 5 H 5 ) 2 ] (MSn, Pb, Mn), [Ca(C 5 M 5 ) 2 (thf) x ] yields the corresponding [M(C 5 Me 5 ) 2 ] complexes. K[C 5 Me 5 ] reacts with [La(C 5 H 5 ) 3 (thf)], [Sn(C 5 H 5 ) 2 ] and [Pb[C 5 H 5 ) 2 ] in toluene to yield the ring‐exchanged products 2 , [Sn(C 5 Me 5 ) 2 ], and [Pb(C 5 Me 5 ) 2 ], respectively.