Photoluminescent Coinage Metal Pyrazolates And Some Group Fourteen Derivatives Of Amino Troponiminates

Fascinating luminescence properties are associated with multinuclear pyrazolato complexes of monovalent coinage metals. Synthetic details, solid-state structures, and photophysical properties of a series of neutral trinuclear, dinuclear, and mononuclear complexes have been studied. Examples include {[3,5-(CF3)2Pz]M}3, {[3,5-(CF3)2Pz]M(L)}2, and H2B[3,5-(CF3)2Pz]2M(L) where M=Cu, Ag, or Au while L=a neutral N-, P-, or C- donor ligand. We have also discovered a series of new tetranuclear complexes, which are unique for these metal ions. Trinuclear complexes exhibit dramatic "luminescence thermochromism". solvatochromism, and "concentration luminochromism",
where different emission colors were obtained by varying the temperature, solvent and concentration, respectively. Monomers, H2B[3,5-(CF3)2Pz]2Ag(L) and H2B[3,5-(CF3)2Pz]2Cu(L) as well as dimers, {[3,5-(CF3)2Pz]Cu(L)}2 and {[3,5-(CF3)2Pz]Ag(L)}2 with L=collidine showed structured blue phosphorescent emissions The nucleophilic and electrophilic character of these complexes can be tuned by varying the substituents on the Pz rings, which also tuned the luminescence in a predictable manner. The phosphorescent nature of the tunable luminescence of these solid adducts and the ease of their sublimation (due to fluorination) are among the desired features that render them attractive candidates as emitting materials in molecular light-emitting devices (MOLEDs) as well as in solvatochromic sensors. Neutral three-coordinate group 14 compounds are expected to show unique properties which make them promising alternatives for phosphines and nucleophilic carbenes as ligands in organometallic chemistry. We are in the process of preparing three-coordinate compounds based on group 14 elements (Ge, Sn, and Pb) using aminotroponiminates [(R1R2)ATI]-. They are excellent ligands in stabilizing divalent group 14 compounds. We have synthesized, a series of such complexes, {[(R1R2)ATI]X} (Where; R1 and R2 = C6H5CH2, 3,5-(CH3)2C6H3, (OCH3)C6H4; M = Ge, Sn, and X = Cl ) containing group 14 elements by varying the N-substituents of the ligand. Synthesis, structures as well as initial studies on coordination chemistry have been carried out by preparing adducts with copper(I) and rhodium(I) complexes.