The synthesis and isolation of d-block metallocenes with more than 18-electron is challenging since metal–carbon bonds become weaker with increasing deviation from the 18-electron configuration. Here the authors report a formal 21-electron cobaltocene derivative by coordination of a two-electron donor to a 19-electron cobaltocene derivative while maintaining the cobalt-carbon bonds.
- Satoshi Takebayashi
- Jama Ariai
- Kazunobu Sato
