Two Mononuclear d10 Metal Coordination Compounds with m-phenol-1,2,4-triazole:Crystal Structures and Properties of Fluorescence and Diffuse Reflectance Spectrum

Although coordination compounds of 1,2,4-triazoles have been known for more than a century, the chemistry of the triazole complexes and the knowledge of their structures and properties have increased rather quickly since the early 1980s. The geometry of 1,2,4-triazole is similar to those of pyrazoles and imidazoles, which is a six-electron aromatic system of five-membered ring. Compared with pyrazoles and imidazoles, the bonding of the 1,2,4-triazole ring with metal complexes has one link more, thus resulting in more rich coordination modes. The triazole ring tends to adopt bidentate (bridging) or tridentate for trizolate anions to construct polynuclear or extending structures. Therefore, mononuclear metal-triazole complexes are rare especially for first-row transition metals. To our knowledge, there exist only a few papers about mononuclear metal-triazole complexes. Besides the coordination chemistry, triazoles have other applications in the wide fields, such as photography, agriculture, medicine and industry. As a readily available and inexpensive resource, 1,2,4-triazole is also a good candidate to synthesize suitable nitrenium ion precursors, and synthetic applications and implication as “ultimate carcinogens” from aromatic amines. In view of coordination character of 1,2,4-triazole, herein two mononuclear coordination compounds, [Cd(HCOOH)(ptr)I2]·H2NCH2NH2 (1) and [ZnCl2(ptr)2]·H2O (2) (ptr = m-phenol-1,2,4-triazole), were synthesized and the crystal structures and properties of fluorescence and diffuse reflectance spectrum were characterized.