Synthesis and characterization of novel covalent biphenyldiyl Sm(II) and Yb(II) complexes

Article abstract of DOI:10.1016/0022-328X(93)80192-E

Biphenylene reacts with activated Sm and Yb powders in ethers giving 2,2'-biphenyldiyl-Sm(II) and -Yb(II) complexes by opening of the C4 ring.They have been characterized by reactions with electrophiles such as the proton and dimethyldichlorosilane, and by 1H, 13C and 171Yb NMR measurements.The Yb complex can be obtained by reaction of 2,2'-dilithiobiphenyl with YbI2.Octamethylbiphenylene, the reduction potential of which is much more negative than that of biphenylene, does not react with Yb powder.In contrast, tricarbonyloctamethylbiphenylenechromium reacts with metal powder due to the presence of the electron-withdrawing Cr(CO)3 group.This suggests that an electron transfer from the metal precedes the opening of the cyclobutane ring.