We report on a new crystal modification of (CuIPy 2 ) n (Py = pyridine), a compound first reported by White et al. In contrast to White’s orthorhombic structure, which is comprised of rhomboid iodide- bridged dimers, Cu 2 I 2 Py 4 , our new tetragonal crystal structure in space group P4 1 2 1 2 is disordered and can be interpreted as either iodide-bridged dimers or helical chains. To determine the structure type, variable temperature X-ray diffraction and luminescence measurements were carried out. The photoluminescence spectrum shows a distinct cluster-centered transition at high excitation energies which is consistent with the dimer structure. DFT and TD-DFT calculations were performed to explain the difference between the emission spectrum at high energies compared to low energies. Furthermore, correlation of the luminescence spectrum with the X-ray results as temperature is varied demonstrates that the cluster-centered luminescence band in Cu 2 I 2 Py 4 arises from close Cu ... Cu distances which vary with temperature. A low temperature X-ray crystallographic redetermination of the cubane tetrameric Cu 4 I 4 Py 4 is also presented. Both Cu 2 I 2 Py 4 and Cu 4 I 4 Py 4 structures show distortion of the Cu n I n core cluster at low temperature resulting in reduced Cu … Cu distances, but with I … I distances roughly unchanged.
JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS
Journal Article URL
Kelly, Andrew W.; Handy, Joseph V.; Nicholas, Aaron; Barnes, Francis; Patterson, Howard H.; Wojtas, Lukasz; and Pike, Robert D., Tetragonal Diiodotetrapyridinedicopper(I): Structure, Luminescence, and Computational Modeling (2017). JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS, 27(Special Issue), 90-100.
This is a post-peer-review, pre-copyedit version of an article published in the Journal of Inorganic and Organometallic Polymers and Materials. The final authenticated version is available online at: 10.1007/s10904-017-0584-y.