Reaction of 1,3-diynes with the electron rich iron complex (η5-C5Me5)(η2-dppe)FeCl. A new and direct access to the iron butadiynyl complex (η5-C5Me5)(η2-dppe)FeCCCCSiMe3

The electron rich iron complexes (C5Me5)Fe(dppe)Cl (3) and (C5Me5)Fe(dppe)Br (4) do not react with Li(CC)nSiMe3 (n=1, 2). Treatment of the chloro iron complex 3 with Me3SiCCCCSiMe3 in methanol and in the presence of NaBPh4 provides the binuclear complex (C5Me5)(dppe)FeCCCCFe(dppe)(C5Me5) (10) as the unique product of this clean reaction (73%). Reaction of the chloro iron derivative 3 with one equivalent of trimethylsilyl(1,3-butadiyne) in triethylamine as a solvent and in the presence of NaBPh4 yields 82% of the mononuclear iron trimethylsilyl-1,3-butadiyne compound. The triethylamine acts as a base to selectively deprotonate the putative butatrienylidene intermediate.