Preparation and Properties of 1,2-Diferrocenyl-Substituted 3,4-Diphosphinidenecyclobutenes and Their Complexes: The First Application of a Diphosphinidenecyclobutene Unit as a Linker of Functional Moieties

Abstract

Compounds with two ferrocenyl units connected with 3,4-diphosphinidenecyclobutene (DPCB) linkers at the 1,2-positions (1) and their transition metal chelate complexes (2) were prepared, and the spectroscopic and electrochemical properties were studied. The compounds were examined by cyclic voltammetry, and ΔE1/2 values (the separation between successive Fe2+/Fe3+ oxidation potentials) were determined. Being fully conjugated with DPCB linkers, those compounds demonstrated electrochemical communication: the Cr(CO)4 complex of 1 (2Cr) showed a strong interaction (ΔE1/2 = 350 mV), whereas PdCl2 and PtCl2 complexes of 1 (2Pd and 2Pt) displayed a decreased interaction compared to that of 1.