The He I photoelectron spectrum of ε-CH2-[(η5-C5H4CH3)Mn(CO)2]2 in the ionization energy range below 11 eV is reported and compared with the ionizations of (η5-C5H4CH3)Mn(CO)3 and (η5-C5H4CH3)Mn(CO)2(C2H4). Excellent agreement is found between the observed ionizations and the predictions of parameter-free molecular orbital calculations. The valence orbitals of the µ- CH2 group appear to have near ideal matching with the frontier orbitals of the (η5-C5H4CH3)Mn(CO)2 fragments to produce the bonding and stability of this cyclopropane analogue. An effective charge transfer from the metals to the methylene occurs in this interaction which results in a high negative charge on the methylene carbon and formation of a net metal-metal bond. The bonding of the bridging methylene in this complex is also compared with the bonding of a terminal methylene with the analogous (η5-C5H5)Mn(CO)2 species. It is concluded that the formation of the metal-metal bond is an important factor in the greater stability of the bridging system.
ASJC Scopus subject areas
- Colloid and Surface Chemistry