Over or under: hydride attack at the metal versus the coordinated nitrosyl ligand in ferric nitrosyl porphyrins
作者:E. G. Abucayon、R. L. Khade、D. R. Powell、M. J. Shaw、Y. Zhang、G. B. Richter-Addo
DOI:10.1039/c6dt03860c
日期:——
Hydride attack at a ferric heme-NO to give an Fe–HNO intermediate is a key step in the global N-cycle. We demonstrate differential reactivity when six- and five-coordinate ferric heme-NO models react with hydride. Although Fe–HNO formation is thermodynamically favored from this reaction, Fe–H formation is kinetically favored for the 5C case.
Role of active oxygen and NOx species in N2O decomposition over Fe-ferrierite
作者:Zdeněk Sobalík、Edyta Tabor、Jana Nováková、Naveen K. Sathu、Karel Závěta
DOI:10.1016/j.jcat.2012.02.007
日期:2012.5
Fe(III)–O species were formed; these species are known to be highly active in oxidations at low temperatures. A transformation of Fe(III)–O into Fe–NOx species occurred when the reaction temperature was increased or when the reaction time was increased at low temperatures. This resulted in the disappearance of the oxidation activity of iron ferrierite. In contrast, the formation of Fe–NOx species enhanced
The interaction of NO with Pt(410) was studied using high-energy resolution fast XPS and temperature programmed desorption/reaction mass spectroscopy. LEED studies show that the surface in the clean state restructures, which results in the formation of some larger 100} terraces. STM measurements show, that most terraces are small, similar to 1 nm. Two different binding energy (BE) components were observed in the N Is region of the core level spectra, both assigned to molecular forms of NO. NO dissociation starts between 350 and 400 K. This is a significantly higher temperature than previous literature reports suggested. This difference is thought to be caused by the restructuring of the surface used in our experiments. The reaction of NO with H-2, NH3 and CO was also studied. The onset of these NO reduction reactions is determined by the NOad dissociation temperature (between 350 and 400 K) and NOad dissociation is the rate limiting step for all the reactions that were studied. Reaction with H2 yields NH3 below 600 K, but the selectivity shifts towards N-2 at higher temperatures. We did not find any indication that reaction between NOad and NH3 ad proceeds via a special NONH3 intermediate. A new surface species was detected during the reaction between NO and CO, both in the N 1s and the C 1s spectrum. It is tentatively assigned to either CN or CNO. The reactivity of NO on Pt(4 10) is compared with the reactivity that was observed for Pt(100) and other noble metal surfaces, such as I'd and Rh. (c) 2006 Elsevier B.V. All rights reserved.
Infrared spectra of (NO)2+, (NO)2−, and (NO)3− trapped in solid neon
作者:Catherine L. Lugez、Warren E. Thompson、Marilyn E. Jacox、Anders Snis、Itai Panas
DOI:10.1063/1.478967
日期:1999.6
New studies of the infrared spectra of the products which result on codeposition at approximately 5 K of a Ne:NO sample with Ne atoms that have been excited in a microwave discharge have led to new and revised assignments for several ionic species. The appearance of the ν1 absorption of ONNO+ for several new species with asymmetric isotopic substitution, but for no symmetrically substituted species, confirms the trans ground-state configuration for ONNO+. The behavior of a neon-matrix product absorption at 1227.5 cm−1 parallels that of an argon-matrix absorption at 1221.0 cm−1 which has recently been assigned to trans-ONNO−. The identity of the carrier of a product absorption at 1424.1 cm−1, contributed by a vibration of two symmetrically equivalent NO groups, has not been definitively established. This absorption exhibits complex photodestruction behavior. Three absorptions are assigned to cis,cis-(NO)3−, which has C2v symmetry, with the aid of density functional calculations of the isotopic substitution pattern for the vibrational fundamentals of this species. Similar calculations of the isotopic substitution patterns for other structures result in poor agreement with the experiments. Photodestruction of cis,cis-(NO)3− trapped in solid neon yields the N2O⋯NO2− complex.
Non-Heme Diiron Model Complexes Can Mediate Direct NO Reduction: Mechanistic Insight into Flavodiiron NO Reductases
作者:Hai T. Dong、Corey J. White、Bo Zhang、Carsten Krebs、Nicolai Lehnert
DOI:10.1021/jacs.8b08567
日期:2018.10.17
present a new diiron model complex, [Fe2((Py2PhO2)MP)(OPr)2](OTf), with bridging propionate ligands (OPr-) that is capable of directly reducing NO to N2O in quantitative yield without the need to (super)reduce the complex. We first prepared the diferric precursor and characterized it by UV-vis, IR, NMR and Mössbauer spectroscopies, cyclic voltammetry, and mass spectrometry. This complex can then conveniently
Flavorodiiron 一氧化氮还原酶 (FNORs) 是一种常见的酶家族,存在于各种类型的病原菌中,能够将一氧化氮 (NO) 还原为一氧化二氮 (N2O),作为一种保护性解毒机制。在病原菌中利用 FNORs 有助于它们在人体内存活和增殖,从而导致慢性感染。在本文中,我们提出了一种新的二铁模型复合物 [Fe2((Py2PhO2)MP)(OPr)2](OTf),具有桥接丙酸配体 (OPr-),能够直接将 NO 以定量产率还原为 N2O,而无需需要(超级)减少复杂性。我们首先制备了二铁前体,并通过紫外-可见光、红外、核磁共振和穆斯堡尔光谱、循环伏安法和质谱法对其进行了表征。然后可以使用 CoCp2 方便地将该复合物还原为二铁复合物。尽管这种二铁复合物具有很高的反应性,但我们已经使用 X 射线晶体学和各种光谱技术成功地分离和表征了该物种。最重要的是,在这种二铁复合物与 NO 气体反应后,我们通过红外气体顶空分析观察到