Halogen-involving weak interactions manifested in the crystal structures of silver(i) or gold(i) 4-halogenated-3,5-diphenylpyrazolato trimersElectronic supplementary information (ESI) available: 1H NMR (1, 2, 5, 6, 7), IR spectra (1-7), TG analysis (1), ellipsoid diagrams of the asymmetric units (1-7), packing diagrams (1, 2, 3, 6, 7), PXRD patterns of 1 and 4, diagrams of the MEP surfaces and LUMO/HOMOs of [Ag(IPh2pz)]3 and [Au(ClPh2pz)]3, and tables of selected bond distances (Å) and bond angl

• Main Authors: Chen, Jing-Huo, Liu, Ya-Mei, Zhang, Jin-Xue, Zhu, Yan-Yan, Tang, Ming-Sheng, Ng, Seik Weng, Yang, Guang
• Format: Journal Article
• Language: English
• Published: 20.05.2014
• ISSN: 1466-8033
• DOI: 10.1039/c4ce00029c

Six triangular silver( i ) or gold( i ) 4-chloro/iodo-3,5-diphenyl pyrazolates, as well as a triangular silver( i ) 4-methyl-3,5-diphenyl pyrazolate, have been synthesized and structurally characterized by single-crystal X-ray diffraction. Comparison and inspection of the Ag/Au Cl/I distances, geometries of C-Cl/I bonds with respect to the Ag 3 or Au 3 triangles, and crystal packing diagrams verify the existence of Ag 3 Cl/I or Au 3 I interactions in some of the structures of the trimers, which are strong enough to impart a substantial effect on the spatial arrangement of the trimers in their solid states. Density function theory (DFT) calculations on the trimers give the molecular electrostatic potential (MEP) surfaces and HOMO/LUMOs, which support that the observed M 3 X structural motifs can be understood on the basis of a weak acid-base interaction having contributions from both ionic δ + δ − attraction and covalent LUMO-HOMO overlap. Calculations also show the existence of the so-called "σ-hole" and the secondary effect to it on the halogen atoms; the structural roles played by them were discussed based on the crystal structures. The Au 3 I interactions are strong enough to dictate the packing diagram of the triangular molecules of gold( i ) 4-iodo-3,5-diphenylpyrazolate in its crystal structure.