Formazans (Ar1-NH-N[double bond, length as m-dash]CR3-N[double bond, length as m-dash]N-Ar5), a class of nitrogen-rich and highly colored compounds, have been known since the late 1800s and studied more closely since the early 1940s. Their intense color has led to their widespread use as dyes, especially in cell biology where they are most often used to quantitatively assess cell-viability. Despite structural similarities to well-known ligand classes such as β-diketiminates, the deprotonated form of formazans, formazanates, have received relatively little attention in the transition metal and main group coordination chemistry arenas. Formazanate ligands benefit from tunable properties via structural variation, rich optoelectronic properties owing to their highly delocalized π-systems, low-lying frontier orbitals that stabilize otherwise highly reactive species such as radicals, and redox activity and coordinative flexibility that may have significant implications in their future use in catalysis. Here, we review progress in the coordination chemistry of formazanate ligands over the past two decades, with emphasis on the reactivity and applications of the subsequent complexes.

中文翻译：

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甲酸酯配合物：合成，反应性和应用。

甲（（Ar1-NH-N [双键，长度为m-虚线] CR3-N [双键，长度为m-虚线N-Ar5），是一类富氮且高度着色的化合物在1800年代后期，并从1940年代初期开始进行了更深入的研究。它们强烈的颜色导致它们被广泛用作染料，尤其是在细胞生物学中，它们最常用于定量评估细胞生存力。尽管与众所周知的配体类别（例如β-二酮）结构相似，但在过渡金属和主族配位化学领域，甲the的去质子化形式甲for却很少受到关注。甲maz酸盐配体因结构变化而具有可调节的特性，由于其高度离域的π系统而具有丰富的光电特性，可以稳定高反应性物种（例如自由基）的低洼边界轨道，以及氧化还原活性和配位柔性，这可能对其未来的催化使用产生重大影响。在这里，我们回顾了过去二十年甲酸酯配体配位化学的进展，重点是后续配合物的反应性和应用。