Highly polarized ruthenium alkynyls with nitrothienyl substituents

Me3SiCCC4H2S-5-NO2 was synthesized in good yield by palladium-catalyzed cross-coupling of ethynyltrimethylsilane and 2-bromo-5-nitrothiophene or 2-iodo-5-nitrothiophene. Reactions of Me3SiCC(C4H2S)NO2 with a series of ruthenium chloride complexes [RuClLL′(Cp′)] gave the alkynyls [Ru(2-CCC4H2S-5-NO2)LL′(Cp′)] (L, L′=CO, PMe2Ph or PPh3; Cp′=C5H5 or C5Me5). These metal complexes, each with a strongly electron-donating metal center at one end and an electron-accepting organic substituent at the other end of a π-conjugated chain, are strongly polarized and are expected to demonstrate non-linear optical activity.