Octamethylbistibole (4a), octamethybibismole (4b), 2,2',5,5'-tetrakis(trimethylsilyl)-3,3',4,4'-tetramethylbibismole (5a), and 2,2',5,5'-tetrakis(trimethylsilyl)3, 3',4,4'-tetramethylbibismole (5b) have been prepared by the reductive coupling of their respective precursor phenyl- or bromopnictoles. The bibismoles are thermochromic, while the bistiboles are not. This is the first observation of differing behavior between analogous distibines and dibismuthines with regard to thermochromicity.
