SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF COBALT COMPLEXES DERIVED FROM CONJUGATED TETRAYNES

Some novel tetrayne complexes RC(2)[Co-2(CO)(4)dppm]C=CC=CC2[CO2(CO)(4)dppm]R (5) (where R = SiMe(3), a; 4-MeC(6)H(4), b; C6H5, c; 4-MeOC(6)H(4), d; 4-FC6H4, e; dppm = 1,2-bis(diphenylphosphino)methane) have been synthesized either by oxidative coupling of RC(2)[Co-2(CO)(4)dppm]C=CH (4) or by lithiation and subsequent hydrolysis of RC(2)[Co-2(CO)(4)dppm]CH = CHCl (8). An X-ray structure determination of 5a reveals that the two Co-2(CO)(4)dppm units are trans to each other. The cobalt units can be removed from 5 by oxidizing reagents.