A variety of fluoro-olefins react with RhCI(PPh,), and Rh, CI , L, to give the carbonyl complexes RhCI(CO)L, [L = Ph3P, (C6F&P, (C,F,),PhP, or (C6F5)Ph2P]. It is suggested that the carbon monoxide is formed by the action of small traces of water present in the reactions on fluoro-olefin complexes of the type RhCl(f1uoro-olefin) L, .The action of hydrogen chloride on RhCI(C,F,X) (PPh,), gives the fluoroethyl complexes RhCI,( CFX*CF,H) (PPh,),, (X = H, F, or CI) and it is proposed that this type of rearrangement occurs in some of the hydrolysis reactions of the complexes RhCl(f1uoro-olefin) L, .N.m.r. data on the fluoroethyl complexes are given.WHILE the complex chlorotris(tripheny1phosphine)rhodium(1) reacts with tetrafluoroethylene at room temperature in methylene chloride to form an olefin complex RhCl(C,F,)(PPh3),,1 it was observed that at 120" in benzene both RhCl(PPh,), and Rh,c12[c6F5)3P]4 react with t etrafluoroe thylene to give quantitative yields of the carbonyl complexes trans-RhCl(CO)L, [L = Ph,P or (C,F,),P] . , The formation of carbonylrhodium complexes under such unusual conditions has led us to investigate this reaction further. Under similar conditions te t rafluoroe t hylene and trans-P t HCl (Et,P) , give small yields of a carbonyl cation trams-PtCl(C0) (Et,P), and the complex Rh(acac) (C,F,) (C2H4) catalyses the acetic acid solvolysis of tetrafluoroethylene to give carbon m ~n o x i d e . ~ A variety of fluoro-olefins and phosphine-rhodium( I) complexes react under varying conditions in sealed vessels to give the carbonylrhodium complexes trans-RhCl(CO)L, [L = (