 This result further demonstrated the power of X-ray crystallography and accelerated the growth of organometallic chemistry.The best known members are the metallocenes of the formula M(C5H5)2 where M = Cr, Fe, Co, Ni, Pb, Zr, Ru, Rh, Sm, Ti, V, Mo, W, Zn.These species are also called bis(cyclopentadienyl)metal complexes.