Transition metal complexes of substituted alkynes. VIII. Complexes of cobalt derived from 1,1,1-Trifluorobut-2-yne

Abstract

The complex Co4(CO)10(CF3C2CH3) is formed at room temperature from dodecacarbonyltetracobalt and 1,1,1-trifluorobut-2-yne. Another monoalkyne complex Co2(CO)6(CF3C2CH3) has been prepared from octacarbonyldicobalt and 1,1,1-trifluorobut-2-yne at room temperature. Treatment with triphenylphosphine converts the complex into Co2(CO)4[P(C6H5)3]2(CF3C2CH3). At 150�, reaction of Co2(CO)6(CF3C2CH3) and 1,1,1-trifluorobut-2-yne gives a small amount of a purple complex which is believed to be Co2(CO)4(CF3C2CH3)3. Similar reactions involving Co2(CO)4(CF3C2CH3) and the alkynes hexafluorobut-2-yne and 3,3,3-trifluoropropyne give the complexes Co2(CO)4(CF3C2CH3)(CF3C2CF3)2 and Co2(CO)4(CF3C2CH3)(CF3C2H)2. Spectroscopic studies have led to an assignment of the substitution pattern in these latter complexes. Tris-alkyne complexes were not isolated from similar reactions between 1,1,1-trifluorobut-2-yne and the complexes Co2(CO)6(CF3C2CF3) and Co2(CO)6(CF3C2H). Three isomers of the π-cyclopentadienone-π-cyclopentadienylcobalt complex, [(CF3C2CH3)2CO]Co(π-C5H5), were obtained from (π-C6H6)Co(CO)2 and 1,1,1-trifluorobut-2-yne after U.V. irradiation for several days. The isomers vary in the arrangement of the substituents attached to the cyclopentadienone ring. All reactions involving 1,1,1-trifluorobut-2-yne have been compared with similar reactions involving the related alkynes hexafluorobut-2-yne and but-2-yne.