A nitrogen-arsenic-nitrogen (NAN) ligand, phenyldiquinolinylarsine (pdqa), was newly synthesized by utilizing diiodophenylarsine as a key precursor. The copper(I) halide (CuX, X = Cl, Br, I) and gold(I) chloride (AuCl) complexes of pdqa were synthesized and their structures were analyzed by NMR spectroscopy and X-ray crystallography. [CuX(pdqa)] formed Development of novel ligands is a pivotal process for advancement of coordination chemistry. Numerous backbones and elements have been investigated for superior catalysts, luminophores, magnetic materials, redox systems, etc. Pincer ligands are a particularly important class because the pincertype complexes can offer high stability and unique reactivity as catalysts. [1,2] Nitrogen, phosphorus, and carbon atoms are typically employed for the three coordination sites. For further diversity of pincer ligands, various elements, e.g., boron [3] and silicon, [4] have been introduced so far. Moreover, incorporation of heavy elements is an emerging strategy toward new class of pincer ligands. [5-7] Germylenes (Figure 1a) [6] and stannylenes (Figure 1b), [7] being analogues of carbene, are used for phosphorus-germanium-phosphorus and phosphorus-tin-phosphorus pincer ligands, respectively. Such carbene-like species require intramolecular donor-stabilization as represented by Nheterocyclic carbenes. For simpler ligand design, heavy element-containing pincer ligands can be constructed by using group 15 elements such as arsenic, antimony, and bismuth. Among them, arsenic is favorable because arsenic(III) has sufficient stability against inversion, oxidation, and decomposition. In comparison, nitrogen has low inversion barrier to cause racemization at room temperature, phosphorus is easily oxidized to be pentavalent state in air, and molecular design for organoantimony and organobismuth compounds is restricted due to relatively unstable Sb-C and Bi-C bonds.

We have recently developed a series of arsenic ligands based on practical synthetic strategies. Herein, three kinds of bidentate arsenic ligands with rigid linkers were selected to construct dinuclear rhombic copper(I) iodide (CuI) complexes, whose structures were analyzed by X-ray crystallography. They had sufficient solubility in organic solvents, and it was confirmed that their coordination forms were kept in the solutions. Intense solid-state emissions were observed even at room temperature, and the emission colors were varied from yellow to red by the ligands.

Aryldiphenylarsines, diarylphenylarsines, and triarylarsines were synthesized by practical methods to utilize the heavy atom effect for phosphorescence. 1‐Naphthyl, 2‐naphthyl, 9‐phenanthryl, and 1‐pyrenyl groups were introduced in the present work. The obtained arene‐substituted arsines showed phosphorescence in solutions at 77 K. On the other hand, 1‐pyrenyl‐substituted arsines showed only fluorescence in the solid states at 77 K, whereas the others exhibited phosphorescence. In addition, oxidation of the arsenic atom promoted fluorescence instead of phosphorescence. X‐ray crystallography and computational calculations were conducted to understand the luminescence behaviors of the arene‐substituted arsines.

Dithieno[3,2-b:2',3'-d]arsole (DTA) is one of the representative arsenic-containing conjugated units. In this work, the effects of the As-substituent on the structure, photophysical properties, and stability were investigated. Surprisingly, the As-substituent...

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