10.1021/ic0508730.s001 Mohammad A. Omary Mohammad A. Omary Manal A. Rawashdeh-Omary Manal A. Rawashdeh-Omary M. W. Alexander Gonser M. W. Alexander Gonser Oussama Elbjeirami Oussama Elbjeirami Tom Grimes Tom Grimes Thomas R. Cundari Thomas R. Cundari Himashinie V. K. Diyabalanage Himashinie V. K. Diyabalanage Chammi S. Palehepitiya Gamage Chammi S. Palehepitiya Gamage H. V. Rasika Dias H. V. Rasika Dias Metal Effect on the Supramolecular Structure, Photophysics, and Acid−Base Character of Trinuclear Pyrazolato Coinage Metal Complexes<sup>†</sup> American Chemical Society 2005 cyclic trinuclear pyrazolate complexes luminescence thermochromic changes form isomorphous crystals Pz acid coinage metal DFT CF Ag Cu energy phosphorescence band trimer Remarkable luminescence properties M 3 complexes 2005-11-14 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Metal_Effect_on_the_Supramolecular_Structure_Photophysics_and_Acid_Base_Character_of_Trinuclear_Pyrazolato_Coinage_Metal_Complexes_sup_sup_/3257410 Varying the coinage metal in cyclic trinuclear pyrazolate complexes is found to significantly affect the solid-state packing, photophysics, and acid−base properties. The three isoleptic compounds used in this study are {[3,5-(CF<sub>3</sub>)<sub>2</sub>Pz]M}<sub>3</sub> with M = Cu, Ag, and Au (i.e., <b>Cu</b><b><sub>3</sub></b>, <b>Ag</b><b><sub>3</sub></b>, and <b>Au</b><b><sub>3</sub></b>, respectively). They form isomorphous crystals and exist as trimers featuring nine-membered M<sub>3</sub>N<sub>6</sub> rings with linear two-coordinate metal sites. On the basis of the M−N distances, the covalent radii of two-coordinate Cu<sup>I</sup>, Ag<sup>I</sup>, and Au<sup>I</sup> were estimated as 1.11, 1.34, and 1.25 Å, respectively. The cyclic {[3,5-(CF<sub>3</sub>)<sub>2</sub>Pz]M}<sub>3</sub> complexes pack as infinite chains of trimers with a greater number of pairwise intertrimer M···M interactions upon proceeding to heavier coinage metals. However, the intertrimer distances are conspicuously short in <b>Ag</b><b><sub>3</sub></b> (3.204 Å) versus <b>Au</b><b><sub>3</sub></b> (3.885 Å) or <b>Cu</b><b><sub>3</sub></b> (3.813 Å) despite the significantly larger covalent radius of Ag<sup>I</sup>. Remarkable luminescence properties are found for the three <b>M</b><b><sub>3</sub></b> complexes, as manifested by the appearance of multiple unstructured phosphorescence bands whose colors and lifetimes change qualitatively upon varying the coinage metal and temperature. The multiple emissions are assigned to different phosphorescent excimeric states that exhibit enhanced M···M bonding relative to the ground state. The startling luminescence thermochromic changes in crystals of each compound are related to relaxation between the different phosphorescent excimers. The trend in the lowest energy phosphorescence band follows the relative triplet energy of the three M<sup>I</sup> atomic ions. DFT calculations indicate that {[3,5-(R)<sub>2</sub>Pz]M}<sub>3</sub> trimers with R = H or Me are bases with the relative basicity order Ag ≪ Cu < Au while fluorination (R = CF<sub>3</sub>) renders even the Au trimer acidic. These predictions were substantiated experimentally by the isolation of the first acid−base adduct, {[<b>Au</b><b><sub>3</sub></b>]<sub>2</sub>:toluene}<sub>∞</sub>, in which a trinuclear Au<sup>I</sup> complex acts as an acid.