Reactions of transition-metal .sigma.-acetylide complexes. 15. Cycloaddition of trans-1,2-bis(methoxycarbonyl)-1-cyanoethene: studies on the mode of ring opening of .sigma.-cyclobutenyl complexes. X-ray structures of two isomers of ruthenium complexes RuC:CPhCH(CO2Me)C(CN)(CO2Me)(CO)(PPh3)(.eta.-C5H5), RuC[:C(CN)(CO2Me)]CPh:CH(CO2Me)(CO)(PPh3)(.eta.-C5H5), and Ru.eta.3-CH(CO2Me)CPhC:C(CN)(CO2Me)(CO)(.eta.-C5H5) | Publicación