Liquid-Assisted Solid-State Reaction: Formation of a Three-Dimensional Hydrogen-Bonded Network and Evidence for Proton Induced Electron Transfer

Abstract

We describe the first observation of the quantitative and rapid synthesis of a (10,3)-b three-dimensional hydrogen bonded network {[Ru(H 2 biim) 3 ](TMA)} 3 5H 2 O (1 3 H 2 O) (H 2 biim = 2,2 0 -biimidazole; H 3 TMA = trimesic acid) via a "liquidassisted" solid-state reaction approach. The reaction occurs within minutes of grinding together [Ru(H 2 biim) 3 ](PF 6 ) 2 and Na 2 HTMA with a few drops of H 2 O 2 as an oxidant and solvent, concomitant with a color change from yellow (Ru(II) ion) to blue-green (Ru(III) ion). The characterization of the solid-state product was achieved by a combination of a single crystal obtained via seeding and powder diffraction experiments. To compare with the solid-state reaction, similar reactions were also carried out in an EtOH solution. Two complexes {[Ru(H 2 biim) 3 ](TMA)} 3 10H 2 O (2 3 H 2 O) and [Ru(H 2 biim) 3 ](HTMA) (3) were isolated in the presence of a polypyridine base, such as 2,2-dipyridylamine or 2,2 0 :6 0 ,2 00 -terpyridine or 1,10-phenanthroline. Complex 2 is a (6,3) honeycomb two-dimensional hydrogen-bonded network. Complexes 1 and 2 are topological isomers. The formation of multiple robust hydrogen bonds between [Ru(H 2 biim) 3 ] 3þ and TMA may trigger the proton transfer from H 2 biim to TMA, then electron transfer, resulting in Ru(III) status. This may provide an effective approach for the generation of high status metal complexes via supramolecular interactions. Importantly, our experiments suggest that solution crystallization may at times offer more product diversity than grinding.

Interaction between biimidazole complexes of ruthenium and acetate: hydrogen bonding and proton transfer

“…Meanwhile, strong hydrogen bonding interaction between these complexes and OAc − anion is observed by ESI-MS experiment in solution 46 and single crystal X-ray determination in the solid state. 22,[48][49][50][51] These two different kinds of interaction (deprotonation and hydrogen bonding) have confused us for a long time, and we could not tell the difference between them spectrally.…”

Lighting up solid states using a rubber

“…In recent decades, various solid-state reaction methods have been developed, most of which rely on the principle of topochemical reactions for creating new substances and materials [32][33][34] . The preorganization of the reactants for minimal atom displacement during the breaking and making of bonds is key to topochemistry, and so highly ordered circumstances or systems with complex technical efforts are necessary 35 .…”