Studies on the reactions of (η5cyclopentadienyl)dicarbonylcobalt with phenyl-1-naphthylacetylene and with phenyl-2-naphthylacetylene, and an X-ray crystallographic determination of one of the products: (η5cyclopentadienyl)-[η4-3,3-di-(1-naphthyl)-2,4diphenylcyclobutadiene]cobalt

Abstract The reactions of (η 5 -C 5 H 5 )Co(CO) 2 with both phenyl-1-naphthylacetylene and phenyl-2-naphthylacetylene have been shown to produce all four possible η 5 -cyclobutadiene-cobalt complexes and all six possible η 4 -cyclopentadienone-cobalt derivatives. The structures of the η 4 -cyclobutadiene-cobalt complexes have been assigned on the basis of proton NMR and mass spectral studies, and unequivocally established by means of an X-ray diffraction investigation for one of the isomers as (η 5 -cyclopentadienyl)[η 4 -1,3-di(1-naphthyl)-2,4-diphenylcyclobutadiene]cobalt. This compound is triclinic, a = 10.88(2), b = 15.710(6), c = 8.728(4) A, α = 95.09(4)°, β = 101.94(2)°, γ = 86.93(3)°. The space group is P 1 with Z = 2. The structure was solved by Patterson and Fourier methods and refined by full-matrix least squares methods (4128 reflections above 3σ) to a final R = 0.036. Bond distances and angles are normal but the cyclobutadiene ring is not quite planar. One of the atoms is 0.047 A out of the plane of the other three apparently to relieve steric stress. The two phenyl rings are almost coplanar with the cyclobutadiene ring (torsion angles 3.9 and 20.4°) while the naphthyl rings are almost perpendicular to it (torsion angles 63.8, 64°).