Fluorine as a ligand substituent in organometallic chemistry: A second chance and a second research career

Energetic preference of dative fluorine manganese bonds over direct manganese manganese bonds in binuclear hexafluorocyclopentadiene manganese carbonyls

“…Since these pioneering studies the chemistry of fluoroolefin metal carbonyl complexes has developed extensively as suitable fluoroolefin ligands became available. 8,9 Co C F 2 In view of this metal carbonyl chemistry of tetrafluoroethylene, the perfluorinated diolefin hexafluorocyclopentadiene, C 5 F 6 , is of interest. The five-membered ring of perfluorocyclopentadiene forces cis geometry simplifying stereochemical issues in its metal complexes.…”

“…In fact, efforts by Seppelt and coworkers to synthesize C 5 F 5 metal complexes from hexafluorocyclopentadiene were unsuccessful. 10 Thus the C 5 F 6 complexes ( 2 , 2 -C 5 F 6 )Fe 2 (CO) 8 and trans-( 3 , 1 -C 5 F 6 )Co 2 (CO) 7 are obtained from reactions of hexafluorocyclopentadiene with Fe 2 (CO) 9 and Co 2 (CO) 8 , respectively ( Figure 2). 11,12 For comparison, the corresponding reaction of Fe 2 (CO) 9 with cyclopentadiene (C 5 H 6 ) under mild conditions gives initially the tetrahapto diene complex 13 ( 4 -C 5 H 6 )Fe(CO) 3 .…”

“…10 Thus the C 5 F 6 complexes ( 2 , 2 -C 5 F 6 )Fe 2 (CO) 8 and trans-( 3 , 1 -C 5 F 6 )Co 2 (CO) 7 are obtained from reactions of hexafluorocyclopentadiene with Fe 2 (CO) 9 and Co 2 (CO) 8 , respectively ( Figure 2). 11,12 For comparison, the corresponding reaction of Fe 2 (CO) 9 with cyclopentadiene (C 5 H 6 ) under mild conditions gives initially the tetrahapto diene complex 13 ( 4 -C 5 H 6 )Fe(CO) 3 . However, under more vigorous reaction conditions the  4 -C 5 H 6 ligand loses hydrogen to give a  5 -C 5 H 5 ligand leading ultimately to ( 5 -C 5 H 5 ) 2 Fe 2 (CO) 2 (µ-CO) 2 as the apparent thermodynamic sink in such systems.…”

“…Previous papers have explored such possibilities for both the iron 18 and cobalt 19 systems using density functional theory. In order to gain further insight regarding possible bonding modes of the hexafluorocyclopentadiene ligand in binuclear metal complexes, we have now used similar density functional methods to study the corresponding manganese carbonyl complexes (C 5 F 6 )Mn 2 (CO) n (n = 10,9,8,7). This research has led to the discovery of a new structural feature in low-energy (C 5 F 6 )Mn 2 (CO) n (n = 8, 7) structures, namely the coordination of a CF 2 fluorine atom as well as the C=C double bonds of the hexafluorocyclopentadiene ligand to the central Mn 2 unit, as indicated by bonding Mn-F distances.…”

Triple decker sandwiches and related compounds of the first row transition metals with cyclopentadienyl and hexafluorobenzene rings: remarkable effects of fluorine substitution

“…19,20 Particularly interesting synthetic targets are the fluorinated analogues of sandwich compounds such as ferrocene. 19,20 Particularly interesting synthetic targets are the fluorinated analogues of sandwich compounds such as ferrocene.…”