Electronic Structure of Metallocarbenes

2) Nucleophilic or Schrock-type of carbenes [17-21]. The triplet carbine, however, has two unpaired electrons at its o(aj ) and it(bj ) orbitals that could 

We should emphasize that Fischer-Tropsch and Schrock type of carbenes are extreme representations of metal carbenoids [17-21]. Furthermore, representation of the metal-carbene bonds in terms of singlet and triplet carbenes is just a convenient way to describe these bonds. For example, both types of metallo-carbenes can be explained on the basis of a singlet carbene fragment very strong it-back donation would lead to the Schrock-type of metallocarbene, while no back donation or a weak n-back donation corresponds to the Fischer-Tropsch type of metallocarbene. Of course, it is also possible to understand both types of metallo-carbenes solely on the basis of the triplet carbene fragment. Once again, the use of either both models or only one of them to understand the nature of the M-carbene bond is just a matter of preference. 

we wish to take a step forward and use principles presented above to introduce a new concept - the designing of a complex with an earth-abundant 

On the basis of the aforementioned analyses, we had previously [25] hypothesized that a catalyst with a combination of earth-abundant transition metal iron 

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