The synthesis and structural analysis of the bis-Co2(CO)6 adduct of the cyclic tetrayne C20H8

The reaction of the cyclic tetrayne 2 with Co-2(CO)(8) at 25 degrees C has yielded the double addition product, C20H8[Co-2(CO)(6)](2), 3 in a 39% yield. Compound 3 was characterized by a single crystal X-ray diffraction analysis. The two Co-2(CO)(6) groupings have been added to two alkyne groups on opposite sides of the tetrayne ring in order to minimize steric interactions. The molecule is centrosymmetrical and the central C-12 ring is planar. The two Go-Co bonds are oriented perpendicular to the plane of the C-12 ring. (C) 1999 Elsevier Science S.A. All rights reserved.