Synthesis and Photoluminescence of Tetracyanidonitridorhenium(V) Complexes with Five-Membered N‑Heteroaromatic Ligands and Photoluminescence-Intensity Change
dataset
posted on 2019-12-17, 08:29 authored by Moe Seike, Kojiro Nagata, Hayato Ikeda, Akitaka Ito, Eri Sakuda, Noboru Kitamura, Atsushi Shinohara, Takashi YoshimuraNovel tetracyanidonitridorhenium(V)
complexes with five-membered
N-heteroaromatic ligands, (PPh<sub>4</sub>)<sub>2</sub>[ReN(CN)<sub>4</sub>L] [L = imidazole (Him) (<b>2</b>), 1-methylimidazole
(Mim) (<b>3</b>), and pyrazole (pyz) (<b>4</b>)] and (PPh<sub>4</sub>)<sub>2</sub>[ReN(CN)<sub>4</sub>L]·L [L = Him (<b>5</b>) and Mim (<b>6</b>)], were synthesized by the reactions
of (PPh<sub>4</sub>)<sub>2</sub>[ReN(CN)<sub>4</sub>] (<b>1</b>) with Him, Mim, and pyz, and their structures were determined by
single-crystal X-ray analysis. The complexes <b>2</b>, <b>3</b>, <b>4</b>, and <b>6</b> showed intense photoluminescence,
with the emission quantum yields (Φ<sub>em</sub>) being 0.65–0.75 in the solid state
at 296 K. In contrast, the Φ<sub>em</sub> and τ<sub>em</sub> values of <b>5</b> are significantly smaller and shorter,
respectively, than the relevant values of <b>2</b>. The interconversion
reactions among <b>1</b>, <b>2</b>, and <b>5</b> accompanied by large photoluminescence-intensity changes were accomplished
by solvent-free reactions and exposure of water. The mechanochemical
reaction of <b>2</b> with 1 mol equiv of Him in the solid state
gave <b>5</b>. Complex <b>5</b> was also obtained by the
mechanochemical reaction of <b>1</b> with 2 mol equivalents
of Him in the solid state. By placing solid of <b>5</b> in water,
the solid showed intense photoluminescence to give <b>2</b>.
Complex <b>1</b> was produced under vacuum at 185 °C from <b>2</b> or <b>5</b>.
