Na(C5H5) in tetrahydrofuran byproducts: P(C6H5)3; under inert atm.; addn. of solid Co-complex to soln. of Na-salt in THF,stirred (room temp., 1.5 h), red soln.; filtration, evapn. to leave an oil, volatile material collected in a liquid N2 trap (Co(CO)2-complex), extn. of oil into pentane, chromy. (alumina, 1. pentane: PPh3, 2. toluene: evapn.: Co(CO)(PPh3));