《科学》（20240719出版）一周论文导读
Science, 19 July 2024, Volume 385，Issue 6706
《科学》2024年7月19日，第385卷，6706期
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化学Chemistry
Synthesis of a stable crystalline nitrene
一种稳定结晶亚硝烯的合成
▲ 作者：MARVIN JANSSEN, THOMAS FREDERICHS, MARIAN OLARU, ENNO LORK, EMANUEL HUPF, AND JENS BECKMANN
▲链接：
https://www.science.org/doi/10.1126/science.adp4963
▲摘要：
氮在其化合物中通常形成三个键。在某些情况下，它可以存在于只有一个键的基序中，但这些亚硝基分子往往具有极短的寿命，并且通过时间分辨光谱可以短暂地观察到。
最近，一类笨重的芳基框架稳定了氮的重同系物，锑和铋的亚硝基类似物。研究者发现，这样的框架也可以稳定亚硝基。该化合物被分离并进行了晶体学表征，电子顺磁共振波谱支持三重态基态。
▲ Abstract：
Nitrogen most commonly forms three bonds in its chemical compounds. In certain cases, it can persist in motifs with just one bond, but these nitrene molecules tend to have extremely short lifetimes and are seen transiently by time-resolved spectroscopy. Recently, a class of bulky aryl frameworks has stabilized nitrene analogs of nitrogen’s heavier congeners, antimony and bismuth. Janssen et al. now report that such a framework can stabilize a nitrene as well. The compound was isolated and characterized crystallographically, and electron paramagnetic resonance spectroscopy supported a triplet ground state.
Ph3PCN2: A stable reagent for carbon-atom transfer
Ph3PCN2: 稳定的碳原子转移试剂
▲ 作者：TAICHI KOIKE, JHEN-KUEI YU, AND MAX M. HANSMANN
▲链接：
https://www.science.org/doi/10.1126/science.ado4564
▲摘要：
在单原子水平上对分子中的化学位点进行精确修饰是化学中最优雅但又最困难的转化之一。为单原子碳的化学选择性引入而专门设计的试剂是一项特别艰巨的挑战。
研究者报告了一个直接的、无叠氮化物的结晶和可分离的化合物Ph3PCN2，这是一种稳定的化合物，其碳原子会连接到两个不稳定的化学基团，PPh3和N2。在不添加任何添加剂的情况下，重氮磷酰化作为包括Ph3PCN在内的片段的高选择性转移试剂，传递端磷酰化的杂环烯和CN2，生成多取代吡唑。
在与醛、无环酮和环酮（R2C=0）的反应中，碳原子取代形成偏乙烯（R2C=C），然后生成炔或丁腈。
▲ Abstract：
Precise modification of a chemical site in a molecule at the single-atom level is one of the most elegant yet difficult transformations in chemistry. A reagent specifically designed for chemoselective introduction of monoatomic carbon is a particularly formidable challenge. Here, we report a straightforward, azide-free synthesis of a crystalline and isolable diazophosphorus ylide, Ph3PCN2, a stable compound with a carbon atom bonded to two chemically labile groups, triphenylphosphine (PPh3) and dinitrogen (N2). Without any additives, the diazophosphorus ylide serves as a highly selective transfer reagent for fragments, including Ph3PCN, to deliver phosphorus ylide–terminated heterocumulenes and CN2 to produce multisubstituted pyrazoles. Ultimately, even exclusive carbon-atom transfer is possible. In reactions with aldehydes and acyclic and cyclic ketones (R2C=O), the carbon-atom substitution forms a vinylidene (R2C=C:) en route to alkynes or butatrienes.
Defective TiOx overlayers catalyze propane dehydrogenation promoted by base metals
由非贵金属促进的有缺陷的TiOx覆盖层催化丙烷脱氢
▲ 作者：SAI CHEN, YIYI XU, XIN CHANG, YUE PAN, GUODONG SUN, XIANHUI WANG, DONGLONG FU, CHUNLEI PEI, ZHI-JIAN ZHAO, AND JINLONG GONG
▲链接：
https://www.science.org/doi/10.1126/science.adp7379
▲摘要：
丙烷脱氢（PDH）制丙烯的工业催化剂是石油基裂化工艺的重要替代品，要么使用昂贵的金属，要么使用对环境不利的金属氧化物。钛纳米片通常是相对较差的丙烷脱氢催化剂，当它们完全包裹金属镍时变得非常活跃。
研究者报道了一种典型的活性较低的氧化物，氧化钛（TiO2），可以与地球上丰富的金属镍（Ni）结合，形成一种非常规的Ni@TiOx催化剂，用于高效的PDH。他们将镍离子装载到氧化铝支撑的氧化钛纳米片上，然后在600°C的氢气气氛中还原它们。
