Reactions of complexes Co2(CO) 6(RC 2R′) with Group V 0 donor ligands; synthesis and spectroscopic characterization of substituted derivatives Co 2(CO) 6− n(L) n(RC 2R′)

Abstract

The reactions of Co 2(CO) 8 with asymmetrically substituted alkynes lead to derivatives Co 2(CO) 6(RC 2R′) ( 1). Substitution reactions of complexes 1 with PPh 3, Ph 2P · CH 2CH 2 · AsPh 2 (arphos) and Ph2P · CH 2 · PPh 2 (dppm) have been attempted. With PPh 3 monosubstituted chiral tetrahedral molecules, characterized by two differently substituted acetylenic 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.