176174-70-2Relevant academic research and scientific papers
Linking metal centres with 1,4-bis(diphenylphosphino)-2,5-difluorobenzene (dpfb): Syntheses and molecular structures of [{Mo(CO)4(μ-dpfb)}2] and [{Mo(CO)4}2(μ-dpfb)(μ-dppa)] (dppa = Ph2PC≡CPPh2)
Hogarth, Graeme,Norman, Tim
, p. 1077 - 1085 (1996)
The rigid diphosphine 1,4-bis(diphenylphosphino)-2,5-difluorobenzene (dpfb) has been prepared via addition of 2 equivalents of lithium diphenylphosphide to 1,2,4,5-tetrafluorobenzene and characterised by multinuclear NMR spectroscopy. Reaction with cis-[Mo(CO)4(pip)2] (pip = piperidine) afforded doubly bridged [{Mo(CO)4(μ-dpfb)}2] 1, while with equimolar amounts of dpfb and bis(diphenylphosphino)acetylene (dppa) the mixed-ligand complex [{Mo(CO)4}2(μ-dpfb)(μ-dppa)] 2 was isolated. Both 1 and 2 have been characterised crystallographically. The dfpb ligand always adopts a syn-type configuration. Complex 1 shows a weak π-stacking interaction between the bridging aryl rings, while in 2 the dppa ligand adopts an anti conformation. Variable-temperature multinuclear NMR experiments revealed that 1 undergoes two fluxional processes in solution; twisting of the central core of the molecule and a low-energy process involving the flipping up and down of molybdenum tetracarbonyl units which interconverts the anti and syn conformations of the diphosphines.
