carbon monoxide in chloroform-d1 Bubbling of CO through frozen soln. of Co-compd. (dry, degassed CDCl3).; Monitoring of react. by NMR over 5 days. After 15 min intermediate is obsd. in increasing concn. during following 22 h. CpCo(CO)2 and org. compd. appear in increasing concn. after 30 h, concurrent with the decrease of intermediate.;