A supramolecular twist to the structures of bis(polyfluorophenyl) mercurials

The crystal structure of Hg(C6F4-o-NO2)(2) 1 is planar with intramolecular Hg-O coordination whereas those of the polymorphs of Hg(C6F4-m-NO2)(2) 2a and 2b have the two aryl rings rotated relative to each other (87 degrees and 59 degrees). At a supramolecular level, both complexes exhibit weak Hg center dot center dot center dot O interactions. Theoretical calculations (B3LYP and MP2) for gas-phase Hg(C6F4-o-NO2)(2) and Hg(C6F4-m-NO2)(2) molecules predict non-planar conformations in both complexes corresponding to one polymorph of the latter (2a). However, when the supramolecular Hg center dot center dot center dot O interactions are included, using a dimeric model, the calculations more accurately predict the observed structures of 1 and 2b.