Homo- and heterobimetallic azines derived from ferrocene and cyrhetrene: Synthesis, structural characterization and electrochemical studies

A new series of asymmetrical heterobimetallic azines [(eta(5)-C5H5)Fe{(eta(5)-C5H4)-C(R) = N-N=C(R-1)-(eta(5)-C5H4)Re(CO)(3)}] (1-3) and symmetrical homobimetallic cyrhetrenyl azines [{(eta(5)-C5H4)-C(R) = N}Re(CO)(3)](2) (4, 5) have been synthesized and were spectroscopically characterized by FT-IR, NMR, EI-MS and cyclic voltammetry. The molecular structures of 1 and 4 were determined using single-crystal X-ray diffraction technique. Based on the oxidation potential of the ferrocenyl units and the high degree of planarity of the [(C5H4)-C(H) = N-N=C(H)-(C5H4)] system in complex 1, we inferred electronic communication between the electron-withdrawing cyrhetrenyl groups through the pi-conjugated azine bridge. The compounds display an (E,E)-configuration about the >C=N-bond, an s-trans conformation for the N-N bond and an anti-conformation for the two organometallic fragments. (C) 2018 Published by Elsevier B.V.