Research on carbon-carbon coupling reactions of haloaromatic compounds mediated by zerovalent nickel complexes. Preparation of cyclic oligomers of thiophene and benzene and stable anthrylnickel(II) complexes

Article abstract of DOI:10.1016/0022-328X(91)83247-2

Dehalogenative carbon-carbon coupling reactions of 3,4-dibromothiophene, 1,2-dihalobenzenes and 9-bromoanthracene using zerovalent nickel complexes as a dehalogenating reagent produced respectively cyclotetrathiophene, triphenylene and 9,9'-bianthracene in good yields.However, two extremely stable arylnickel(II) complexes, Ni(10-X-9-anthryl)X(PPh3)2 (X = Br, Cl), where the 10-C-X bond in the anthryl groups was inert against excess Ni⁰ complexes, were obtained by oxidative addition of 9,10-dihaloanthracenes to the Ni⁰ complexes.Under similar reaction conditions 9,10-dihaloanthracenes did not undergo carbon-carbon coupling reactions.