A click approach to polymetallic chromium(0) and tungsten(0) Fischer-carbene complexes and their use in the synthesis of functionalized polymetallic metal-carbene complexes

Alkynylamino Cr and W Fischer carbenes undergo a CuAAC reaction with a diverse range of di-, tri-, and tetra-azides to produce polymetallic chromium(0) and tungsten(0) (Fischer)-carbene complexes in good-to-excellent yields. This method is simple, versatile, and is suitable for the preparation of a diverse range of structures with a high level of symmetry. Moreover, the resulting polymetallic carbene complexes are suitable partners for the peripheral functionalization of the metal nuclei, whilst retaining the metal fragment. This fact has been demonstrated in a simultaneous Pauson-Khand reaction, which, in some cases, allows for the generation of four bicyclic [5,5] rings on the periphery of a tetrametallic molecule in a process that involves the formation of 12 new C-C bonds, with four simultaneous CO-insertion processes. The electrochemistry of the polymetallic Fischer carbenes show completely independent behavior for each nucleus, as well as an anomalous observation of the reversible oxidation of the allyl substituents, which has not been reported before in this class of chemistry. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.