A series of 2, 6-ethynylpyridyl compounds BrC5H3N (C2) R, C5H3N [(C2) R] 2, BrC5H3N [RC2Co2 (CO) 4dppm], C5H3N {[R′ C2Co2 (CO) 4dppm] C2R} and C5H3N [(R2C2Co2 (CO) 4dppm)] 2 (R′= H, SiMe3, Fc), C5H3N (C2SiMe3)(C2R) R= H, Fc,{C5H3N (C2SiMe3) 2} and {C5H3N [C2C5H3N (C2SiMe3)] 2} have been prepared in order to study through- space and through-bond interactions between the ethynyl arms. The structure of BrC5H3N ...