eta(2)-alkinyl and vinylidene transition metal complexes .3. Reactivity of acetylide [(eta(5)-C5H5)(CO)(NO)W(C C-R)](-) with [(eta(5)-C5H5)(CO)(2)Fe(THF)]BF4: Synthesis, structure and photochemical behavior of a tungsten iron acetylide

Reaction of metalate anion [(eta(5)-C5H5)(CO)(NO)W(C=C-R)](-) (6a R = C6H5, 6b R = C6H4-CH3, 6c R = C(CH3)(3), 6d R = Si(CH3)(3)) with [(eta(5)-C5H5)(CO)(2)Fe(THF)]BF4 as electrophile leads to bimetallic eta(2)-alkyne complexes {[(eta(5)-C5H5)(CO)(NO)W]eta(2)-(eta(5)-C5H5)(CO)(2)Fe-C=C-R]} 8a-d in 47-57% yields as brown-red, air-stable crystals. These complexes are converted to the diastereomeric mixtures of bridged sigma, pi-acetylides 9a-d/10a-d upon photodecarbonylation. The crystal structures of {[(eta(5)- C5H5)(CO)(NO)W]eta(2)-[(eta(5)-C5H5)(CO)(2)Fe-C=C-C6H5]} 8a and ([(eta(5)-C5H5)mu-(CO)(NO)W]eta(2)-(eta(5)-C5H5)(CO)Fe-C=C-C6H5)]} 10a were determined.