Modified molybdenum and tungsten metallocenes and ring-slippage reactions: new compounds and revisited concepts

Abstract

A systematic method for the synthesis of ringmodified metallocenes of Mo and W was developed producing a variety of substituted Cp-, indenyl-and fluorenyl-containing analogues Cp' 2 ML 2 . Preferred coordination of Z Z Z Z 3 -Flu in the exocyclic fashion was definitely established on experimental and theoretical grounds. The redox chemistry and electrochemistry of these complexes is coupled with ring-slippage between the extreme coordinations [Cp(Z Z Z Z 3 -Cp')ML 2 ] and [CpCp'ML 2 ] 2+ ; (Cp' = Cp, Ind). DFT calculations reveal thatring slippages are exothermic for both Cp and Ind rings. A subtle dependence of ring-slippage on the nature of the ancillary ligands has been explained with the help of DFT calculations.Figure 2 Endocyclic (left) and exocyclic (right) coordination modes of Z 3 -flu.