4. Conclusion

The first carbene complex was discovered and prepared by E.O. Fischer in 1964. It was undoubtedly to his great credit that he understood the need to work at low temperature to enable stabilization of the intermediate compound [(CO) ₅ W{C(OLi)CH ₃ }], essential for the preparation of this complex. No doubt he also understood the nature of the polarities carried by the atoms and their origin in order to bring about the doublet tipping necessary for the elaboration of this carbene complex.

These polarities and doublet flip-flops have been extensively described throughout this article to explain and exploit the exceptional properties of these compounds, as all these reactions take place at particularly low temperatures. The developments that followed were considerable; in particular,...