Influence of the difluoromethylene group (CF2) on the conformation and properties of selected organic compounds

The CF2 group has found applications as a substituent in all classes of organic chemical products from medicinal products to materials, although it is less frequently encountered than the C-F and CF3 substituents. In this review, the geometric influence of placing two fluorine atoms on carbon is considered and in particular, deviations from tetrahedral geometry are noted. The incorporation of the CF2 group into CF2 phosphonates as phosphate mimics is reviewed and the geometric and steric influences of the CF2 group are considered when the substituent is placed within aliphatic chains and aliphatic ring (cyclo dodecane) systems.