New [2]Boraferrocenophane and Diferrocenyldiborane(4) Derivatives

The new [2]boraferrocenophane derivative [Fe(η 5 ‐C 5 H 4 )–B(Mes)–B(Mes)–(η 5 ‐C 5 H 4 )] ( 2 ) was prepared by reaction of 1,1′‐dilithioferrocene with B 2 (Mes) 2 Cl 2 . In addition, the diborane(4) B 2 (NMe 2 ) 2 Fc 2 ( 3 ) was isolated from the reaction of B 2 (NMe 2 ) 2 Cl 2 and monolithioferrocene. Both species were fully characterized including X‐ray diffraction analyses. While B 2 (NMe 2 ) 2 Fc 2 ( 3 ) adopts an unstrained geometry, [2]boraferrocenophane 2 features notable molecular ring strain manifested in the tilt‐angle a = 10.5(2)°.