A NEW BOW-TIE - SYNTHESIS AND X-RAY STRUCTURE OF CO2RU3(MU(5)-ETA(2)ETA(2)-PHC(2)C(2)PH)(CO)(14), WHICH SHOWS A REMARKABLE AND UNUSUAL ASYMMETRY IN THE SOLID-STATE

The reaction between Ru-3(mu(3)-eta(2)-PhC(2)C(2)Ph)(mu-CO)(CO)(9) and Co-2(CO)(8) affords the pentametal cluster Co2Ru3(mu(5)-eta(2)-PhC(2) C(2)Ph)(CO)(14) in quantitative yield. The X-ray determined molecular structure consists of a Co2Ru3 bow-tie cluster which is straddled by t he PhC(2)C(2)Ph ligand, interacting with all five metal atoms via the two C drop C triple bonds, each of which is attached in the 2 sigma(2R u),pi(Co) bonding mode. Of the 14 CO groups, one bridges one Co-centra l Ru bond in one half of the molecule, while two are found semibridgin g the central Ru-Co and -Ru vectors in the other half of the molecule. In the solid state, there is thus a curious and remarkable asymmetry between the two halves of the molecule, although in solution at room t emperature the molecule appears to be symmetrical.