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Synthesis, Structure and Electrochemistry of Macrocyclic Tetrametallic Group 6 (Fischer) Carbene Complexes


  • For a preliminary communication of a part of this work, see ref.1


The 1,4-addition of diamine dinucleophiles to dimetalliccarbene scaffolds 5 yields tetrametallic azamacrocycles 9 and 10 with exocyclic metal–carbene nuclei, in excellent yields and with high stereocontrol. All-Z stereoisomers are isolated in all cases, with the exception of the tungsten(0) macrocycle 10, which is obtained as a mixture of isomers. This methodology allows the preparation of a new type of homo- and heterocyclophane metallomacrocycles in which the geometry and the size of the cavity can be designed as a function of the biscarbene complexes employed and the diamines used as linkers. The X-ray structure of complex 10a showing the high stability of the Z configuration of these compounds and the electrochemistry of the metallomacrocycles prepared are also reported.