REACTIONS OF COMPLEXES CO-2(CO)(6)(RC(2)R') WITH GROUP V-O DONOR LIGANDS - SYNTHESIS AND SPECTROSCOPIC CHARACTERIZATION OF SUBSTITUTED DERIVATIVES CO-2(CO)(6-N)(L)(N)(RC(2)R')

The reactions of Co-2(CO)(8) with asymmetrically substituted alkynes lead to derivatives Co-2(CO)(6)(RC(2)R') (1). Substitution reactions of complexes 1 with PPh(3), Ph(2)P . CH2CH2 . AsPh(2), (arphos) and Ph(2)P . CH2 . PPh(2) (dppm) have been attempted. With PPh(3) monosubstituted chiral tetrahedral molecules, characterized by two differently substituted acety]enic carbon atoms and by two cobalt atoms with different ligand arrangement have been obtained (complexes 2); some disubstituted derivatives have also been observed (complexes 3). The equatorial or axial position of the phosphines is discussed. With dppm bridged Co-2(Co)(4)(dppm)(PhC=C . C(=O)Me) (5) is obtained, whereas with arphos a chelate compound (4) is the main product. The complexes have been characterized by means of elemental analyses, mass spectrometry and spectroscopic techniques.