Structural Aspects of Halocuprate and Haloargentate Anions in Supramolecular Systems

Doctoral thesis, 2002

There is a growing interest in designing and engineering crystals of compounds with desired structures and properties. In this context, a better understanding of the intermolecular interactions present in crystals is of importance and much work is currently being directed towards this goal. The work in this thesis is centered on understanding the structure-determining forces in compounds containing halocuprate and haloargentate anions. Several new complexes have been synthesised and their structures determined using X-ray diffraction. Subsequently, the crystal packings have been analysed with respect to attractive intermolecular interactions. In some cases, computational calculations using Force Field methods or Density Functional methods were employed to better understand the energetics involved. Experimental work also included solution investigations using Mass Spectrometry. The results show that the systems studied are generally structurally flexible and the specific anionic species are often a consequence of attractive cation-cation and cation-halide interactions. These interactions are believed to be important both in the crystal and in solutions of the relevant species. Two new halocuprate anions of unusual geometry have been isolated: [Cu(II)X3]- (1 & 2) and [Cu(II)X3·MeCN]- (3), where X = Cl/Br. The geometry of 1 and 2 is distorted trigonal planar and in 3 the coordination number of copper is 3+1 and the anion has a distorted trigonal pyramidal geometry with the acetonitrile molecule situated at the apex of the pyramid.