STRUCTURAL METHODS OF CHARACTERIZATION

Because nearly every element in the fluorine and polyanion species studied contains at least one NMR-active nuclide, multi-NMR is extensively used for structural characterization in solution. Low-temperature Raman spectroscopy and X-ray crystallography are used to arrive at detailed structural characterizations in the solid state. We have developed methods in our laboratory to mount air-sensitive and thermally unstable crystals of strongly oxidizing compounds at low temperature for low-temperature single crystal X-ray diffraction which have provided us access to the detailed structures of large number of highly reactive air-sensitive species, e.g., salts of KrF⁺, Kr₂F₃⁺, ClF₆⁺, BrF₆⁺ as well as the volatile, highly air-sensitive and radioactive molecule, TcOF₅. Quantum-chemical calculations are routinely used to determine if the energy-minimized geometries are consistent with those obtained experimentally in solution and in the solid state and to understand their thermochemical behavior. This wedding of synthetic structural chemistry and computational methods also provides a nearly unambiguous method for making full vibrational (Raman and infrared) assignments of the compounds we study.

 

TRAINING OF HIGHLY QUALIFIED PERSONNEL

All research programs involve the combination of challenging synthetic and structural characterization work that employ an arsenal of structural techniques (multi-NMR spectroscopy, X-ray crystallography, Raman and infrared spectroscopies and radiochemical methods). Characteristically, nearly all of the compounds that are targeted are at the very edge of existence and are extremely difficult to synthesize, handle and structurally characterize. The rigors of fluorine chemistry, in particular, demand an "apprenticeship" style approach to teach the use of specialized equipment and procedures. The diversity of characterization techniques and the rigors of challenging chemistry routinely dealt with in our laboratory provide co-workers with a broad outlook and training that enables them to better innovate problem solving strategies in the technical environments they will encounter in both industry and academia.

There are currently few research groups worldwide in which students and postdoctoral fellows can be trained in the basics and rigors of “hardcore”, fluorine chemistry that deals with highly reactive fluoride materials and elemental fluorine. Imparting such knowledge and skills is vitally important to the fluorochemical industry where former coworkers are making significant contributions to contemporary industrial fluorine chemistry. Some areas these individuals have already impacted are fluorinating agents for fluorinated drugs such the leading asthma medications, fluorinated glasses for fiberoptics, hydrogen fluoride production (the precursor and basis for the entire fluorochemical industry and of major importance to the petrochemical industry), fluorinated materials, to name a few. In addition, this laboratory has spawned academics who actively pursue research programs related to ¹⁸F-labelled radiopharmaceuticals, inorganic main-group and transition metal fluoride chemistry, and solid-state NMR spectroscopy of inorganic fluorides.