Abstract
The nickel alkyne complexes (dippe)Ni(PhC⋮CPh), 1, (dippe)Ni(MeC⋮CMe), 2, (dippe)Ni(MeO2CC⋮CCO2Me), 3, (dippe)Ni(CH3OCH2C⋮CCH2OCH3), 4, and (dippe)Ni(CF3C⋮CCF3), 5, were synthesized (dippe = bis(diisopropylphosphino)ethane) and characterized by 1H, 31P, and 13C{1H} NMR spectroscopy. Complexes 1, 2, and 3 were characterized by X-ray crystallography. The thermolysis of complex 1 or 2 (120 °C) in the presence of excess biphenylene and excess alkyne results in very slow catalytic formation of the corresponding 9,10-disubstituted phenanthrene. However, addition of ∼6 mol % O2 (based on the metal complex) to the reaction mixture results in an acceleration in catalysis at lower temperatures (∼70−80 °C). The thermolysis of complexes 3 or 4 with excess biphenylene and excess alkyne leads to the alkyne cyclotrimerization product as the major organic species formed in the reaction. Fluorenone was catalytically produced by heating (dippe)Ni(CO)2, biphenylene, and CO. Catalytic insertion of 2,6-xylylisocyanide into the strained C−C bond of biphenylene was also achieved by heating (dippe)Ni(2,6-xylylisocyanide)2, excess biphenylene, and 2,6-xylylisocyanide. Mechanistic schemes are proposed for these reactions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.