Improved access to{1ω-(phosphanyl)alkylcyclopentadienyl}cobalt(1) complexes: Decomplexation of the phosphane arm; alkyne complexes; synthesis of monouclear vinyiideneeobalt (I) complexes

Article abstract of DOI:10.1002/cber.19961290312

An improved synthesis of [(2-phosphanylethyl)cyclopentadienyl]cobalt(i) chelate complexes is presented, in which the paramagnetic chloride 3 is a precursor of the ethene complex 4. The latter readily undergoes ligand exchange reactions which in the case of bidendate reagents (1,5-cyclooctadiene, l,2-bis(diisopropylphosphanyl)ethane, 2,2′-bipyridine, norbornadiene) cause a decomplexation of the phosphane arm at room temperature with formation of 7, 5, 6, 8. The ethene ligand in 4 can be replaced by alkynes under equally mild reaction conditions {formation of 9, 11-16). The reaction with ethyne results in the formation of vinylidene complex 10. The yields of the reactions with nonarornatic alkynes could be improved by treating 3 with the alkyne in the presence of sodium amalgam. The unsubstituted vinylidene complex 10 and its fert-butyl derivative 17 were obtained by this route in 88 and 40 % yield, respectively. VCH Verlagsgesellschaft mbH, 1996.