| Abstract: | The reaction of (η5-cyclopentadienyl)(η4-1,3-diphenylcyclobutadiene)cobalt ( I ) with excess Cr(CO)3py3 in BF3OEt2 yielded two identified heterometallic compounds. Compounds II and III with one and two phenyl rings complcxed with Cr(CO)3 fragment(s), respectively. These compounds were characterized by mass, infrared, 1H and 13C NMR spectra and elemental analysis. The crystal structure of II was determined. The Cr(CO)3 fragment bends inward toward the cyclobutadicne ring due to its electron-withdrawing ability, in accord with Hunter's postulate. A sharp line due to the non-complexed phenyl ring was observed in the 1HNMR spectrum, which implies that five protons are magnetically equivalent. The chemical shifts of two protons of the cyclobutadiene ring decreased from I to II then to III , possibly because of diminished deshielding effect from the phenyl ring in (arene)Cr(CO)3. |
