This poster will present analyses of a series of pseudosymmetrical transition metal oxide-fluoride compounds and their structural properties. Despite having very similar connectivity,some of the compounds are centrosymmetric (CS), while others are noncentrosymmetric (NCS).The knowledge of how NCS structures can be more stable than related CS structures is useful todevelop strategies for guided inorganic synthesis of new NCS materials. Organiccrystallography has demonstrated that lambda (?)-shaped molecules can reliably stack togenerate polar structures, and recently this concept has been applied to inorganic structures.Combining this concept with qualitative bond valence sum (BVS) structural analysis makes itpossible to explain the peculiarities of this class of oxide-fluoride materials.We hydrothermally synthesized several compounds with the general formulaK10(M2OnF11-n)3X (M = V, Nb; n = 2; X = (F2Cl)1/3, Br,(Br3Br)1/2,(I3I)1/2; M = Mo, n=4, X =Cl, (Br3Br)1/2,(I3I)1/2). Compounds crystallized either in CS space groups (P�3m1 or C2/m) or inan NCS space group (Pmn21). All compounds contain linear, (pseudo)hexagonally coordinatedchannels occupied by disordered halides, as well as having the same general structure of anionicbuilding units. The anionic building units present in these structures contain two transition metalions joined by a shared fluoride ion. In several of the compounds this M-F-M bridge is bent togive the building units a (?)-shape; this bend also makes the building unit polar. The occurrenceof the ? shape is explained using BVS analysis of the building unit and its environment andapplication of the distortion theorem. The implications of the influence that stabilize the ?distortion will be discussed to examine their possible application for synthesizing new NCScompounds.

Noncentrosymmetry in oxide-fluorides from stabilized polarizing distortions

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.