This Part 2 of  acids and bases illustrates the implementation of the “Research for the Classroom” program in this 4610/5560 course “Research for the Classroom” is a program I am currently implementing as proposed in the Educational Component of my active NSF-CAREER proposal. Some classroom students perform a small research project instead of writing a term paper. The classroom students’ findings are incorporated into research papers that relate the findings to experimental and computational data in my and my collaborators’ labs or from the literature. Three success stories are illustrated here by students in this 4610/5560 class.

M = Cu; Ag; Au Metal effect??… R= e-withdrawing (e.g., CF 3 )  Should make it a  acid R= e-releasing (e.g., Me; i-Pr; t-Bu)  should make it a  base

Project given as a classroom assignment to: Alex Gonser: Chem 5560 student in Fall 2003 (in collaboration with his advisor, Dr. Cundari)

DFT-calculated electrostatic potentials mapped on the electron density surfaces of M 3 Pz 3 complexes. Color code: blue=most positive=  acid red=most negative=  base Yellow = weak  base Green = very weak  base Cu 3 Pz’ 3 Ag 3 Pz’ 3 Au 3 Pz’ 3 Pz’ have Me groups on the Pz rings (inductive effect of Me renders all trimers basic)

These triangles are unsubstituted M 3 Pz 3 trimers with M = Cu, Ag, Au Positive charge {PzAu}

All strong  acids: The inductive effect of CF 3 renders all trimers acidic, even the Au trimer. Contrast the following: {[3,5-(CF 3 ) 2 Pz]Au} 3 {PzAu} 3

These findings by Alex combined with other experimental data led to a paper just published in Inorganic Chemistry (the premier journal in inorganic chemistry) that was selected to be featured on the JOURNAL COVER… Trinuclear pyrazolate ring complexes of coinage metals exhibit startling luminescence thermochromism due to intertrimer M-M excimeric bonding in their supamolecular stacks. Though unsubstituted {[Pz]M}3 trimers are bases (Au> Cu >> Ag), fluorination renders even the Au trimer acidic, leading to the isolation of the first acid-base adduct in which a trinuclear AuI complex acts as an acid. See M. A. Omary, M. A. Rawashdeh-Omary, M. W. A. Gonser, O. Elbjeirami, T. Grimes, T. R. Cundari, H, V. K. Diyabalanage, C. S. Palehepitiya Gamage, and H. V. R. Dias, p 8200.

M= Cu; Ag; Au Substituent effect: R= e-withdrawing (e.g., CF 3 )  makes it more of a  acid R= e-releasing (e.g., Me; i-Pr; t-Bu)  makes it more of a  base Metal effect: Relative  basicity: Au>Cu>Ag Relative  acidity: Ag>Cu>Au SUMMARY If you want to react with naphthalene (  base), what would you choose for R and M to form an acid-base adduct?

Maha Eldabaja (4610 student here doing research in the Omary group)….just got crystals of an adduct for [Ag(3,5-(CF 3 ) 2 Pz)] 3 with naphthalene and found that it has green emission, consistent with naphthalene phosphorescence

(let’s hear it for Maha!!) Chi2: Durbin Watson: 1.85 Z: Pre-exp. 1: 825.2±1.638E+001 Lifetime 1: 1.575E+004  s ±6.652E+002 Offset: 26.5  = 15.8 ± 0.7 ms

OK so we studied substituent and M effects, how about the effect of the bridging ligand itself? Project THIS SEMESTER for Samer Tekarli

{PzAu} 3 {(carb)Au} 3 {(im)Au} 3 {TzAu} 3 {(C 6 H 4 )Hg} 3

NeutralAniondHNeutralAniondH Carbeniate Imidazolate Pyrazolate Tyrazolate Triphenyl (-1) Triphenyl (-2)

Ag

Au

Cu

HOMO_1 (54=53)

HOMO_2 (53=54)

LUMO (55)