Polyterthiophene π-conjugated by organomolybdenum complex (II):: electropolymerization of erythro-[(η5-C5H5)2Mo2-(O)2(μ-O){μ-η2:η2-C(Ph)C[C4HS(C4H3S-2)2-2,5]}]

Terthiophene, to which the organomolybdenum oxide cluster complex is pi-conjugated, erythro-[eta(5)-C5H5)(2)Mo-2(O)(2){mu-eta(2):eta(2)-C(Ph)=C[C4HS(C4H3S-2)(2)-2,5]}] (2) was prepared by treatment of erythro -[(eta(5)-C5H5)(2)Mo-2(CO)(4){mu-eta(2):eta(2)-C(Ph=C[C4HS(C4H3S-2)(2)-2,5]}] (1) with air in the presence of trimethylamine N-oxide in 1:1 MeCN-CH2Cl2. The structure of 2 was identified by spectroscopic methods and elemental analysis. CV of 2 in TBAP-CH2Cl2 solution exhibits three discrete electrode processes. Two reversible processes, at E-pa = 0.89 and 1.08 V, are associated with the oxidation of the cluster core to the radical cation, [Mo(2)core](.+) and dication, [Mo(2)core](2+), respectively. Irreversible process at E-pa = 1.30 V can be assigned to the terthiophene moiety. Electrochemically active, polymer film of 2 shows an electrochromic switching between shiny purple (undoped) and transparent blue (doped), which is sharply discerned form the color contrast of the typical polythiophenes as well as 1. Such a unique electrochormism can be ascribed to the direct pi-electronic interaction between the conjugated organomolybdenum cluster and the polythiophene backbone. (C) 2000 Elsevier Science S.A. All rights reserved.