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

Abstract

Hexafluorocyclopentadiene is known to form binuclear complexes with metal carbonyls, for example ( 2 , 2 -C 5 F 6 )Fe 2 (CO) 8 and trans-( 3 , 1 -C 5 F 6 )Co 2 (CO) 7 . In order to evaluate the prospects for related manganese carbonyl chemistry, the C 5 F 6 Mn 2 (CO) n (n = 10, 9, 8, 7) systems were investigated using density functional theory. For the C 5 F 6 Mn 2 (CO) 10 system, structures with the Mn(CO) 5 units bonded to non-adjacent ring carbon atoms and/or on opposite sides of the C 5 F 6 ring are energetically preferred over isomeric structures with the Mn(CO) 5 units bonded to adjacent ring carbon atoms and/or on the same side of the C 5 F 6 ring. For the unsaturated C 5 F 6 Mn 2 (CO) n (n = 9, 8, 7) systems, structures containing dative FMn bonds from one or both CF 2 fluorine atoms to one or both manganese atoms are energetically preferred over structures containing formal Mn-Mn bonds. In this way the manganese systems differ significantly from the previously studied iron and cobalt systems.