Crystallography in Canada 

Comments on QTAIM

T. Stanley Cameron

Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, Canada 
Reprinted from CNCC Newsletter No 1 (Canadian National Committee for Crystallography) September 2009

T. Stanely Cameron

The QTAIM approach to the examination of electron density has provided crystallographers with a remarkable tool to examine, experimentally, the fine details of the electron density throughout a crystal. Our group here at Dalhousie has been specializing in the collection of high-angle, low-temperature, multi-redundant X-ray diffraction data to examine the weak interactions present in crystals. In a series of papers we are beginning to see that although many of the C-H...X and even H...H interactions are weak, they are, with the insights from QTAIM, clearly detectable. Moreover for many of these weak interactions it begins to appear that they are far more logically organized that was ever suspected. The result is that the species in crystals are often held in place not just by the familiar conventional forces but also by a multitude of Lilliputian tethers.