Reactions of a partially fluorinated diphenylacetylene with some carbonyl complexes of cobalt and rhodium

Abstract

The alkyne C6F4HC~CC6Hs has been isolated from the reaction of phenylethynylcopper(~) with 1,2-diiodotetrafluorobenzene in refluxing pyridine. Spectroscopic properties indicate the alkyne is phenyl(2,3,4,5-tetrafluoropheny1)ethyne. The reactions of C6F4HGCC6H5 with (q-C5H,)Co(CO), and (q-C5H5)Rh(CO), have been compared. With (~-C,H,)CO(CO)~, three isomers of the cyclopentadienone complex (q-C5H5)Co[C4(C6F4H)Z(C6H5)2CO] were isolated in addition to the cyclobutadiene complex (q-C5HS)Co[C4(C6F4H)2(C6H5)2] and the substituted benzene C6(C6F4H)3(C6H5)3. The reaction with (q-C5H5)Rh(C0)2 also gives C6(C6F4H)3(C6H5)3 and three isomers of (q-C,H,)- Rh[C4(C6F4H)2(C6H5)2CO], but some additional organometallic and organic products are formed. These include the organorhodium complexes (C5H5)3Rh3(CO)(C6F4HC2C6H5), (CsH5)3Rh3(C6F4HC2C&) and (C5H5)2Rhz(C6F4HC2C6Hs)2, and an organic compound of formula (C6F4HC2C6H5)4. Treatment of CO~(CO)~ with C6F4HC~CC6H5 has given the'p-alkyne complex CO~(CO)~(C~F~H- C2C6H5). Thermal degradation at 180-190" of this complex yields a range of organic products including two isomers of the cyclopentadienone compound C4(C6F4H)2(C6H&C0, the substituted benzene C6(C6F4H)3(C6H5)3, and an oligomer (C6F4HC2C6H5),.