Krahe Oliver, Neese Frank, Engeser Marianne
Max-Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr (Germany).
Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn (Germany).
Chempluschem. 2013 Sep;78(9):1053-1057. doi: 10.1002/cplu.201300182. Epub 2013 Jul 5.
The Fe azide complexes [Fe (N )cyclam-ac]PF (1⋅PF ), [Fe (N )Me cyclam-ac]PF (2⋅PF ), and trans-[Fe (N ) cyclam]ClO (3⋅ClO ) (cyclam=1,4,8,11-tetraazacyclotetradecane; cyclam-ac=1,4,8,11-tetraazacyclotetradecane-1-acetate; Me cyclam-ac=4,8,11-trimethyl-1,4,8,11-tetraazacyclotetra-decane-1-acetate) are studied in the gas phase with special emphasis on the formation of high-valent iron nitrides by collision-induced dissociation. Whereas the azide complex with unsubstituted cyclam-acetate 1 as major fragmentation expels N to form a high-valent Fe nitride complex, a similar process is not observed for its methyl-substituted congener. In contrast, loss of an azide radical results in iron reduction to Fe . Thus, the gas-phase behavior is parallel to the results obtained in spectroscopic studies of photolyzed frozen solution. The diazide complex 3 mainly fragments via consecutive losses of HN without change in the iron oxidation state. However, small amounts of dinitrogen loss and thus Fe nitride formation are also observed. While it is assumed that the Fe nitride complex detected by Mössbauer spectroscopy in frozen solution is still coordinated by an azide in the trans position to the nitride, both the complex [Fe (N)(N )(cyclam)] still bearing an intact second azide and the coordinatively unsaturated [Fe (N)(cyclam-H)] are observed in the gas phase.
研究了叠氮铁配合物[Fe(N₃)cyclam-ac]PF₆(1·PF₆)、[Fe(N₃)Me₃cyclam-ac]PF₆(2·PF₆)和反式-[Fe(N₃)₂cyclam]ClO₄(3·ClO₄)(cyclam = 1,4,8,11-四氮杂环十四烷；cyclam-ac = 1,4,8,11-四氮杂环十四烷-1-乙酸酯；Me₃cyclam-ac = 4,8,11-三甲基-1,4,8,11-四氮杂环十四烷-1-乙酸酯)在气相中的情况，特别强调了通过碰撞诱导解离形成高价铁氮化物。未取代的环四胺乙酸酯的叠氮配合物1主要通过排出N₂形成高价铁氮化物配合物，而其甲基取代的同类物未观察到类似过程。相反，叠氮自由基的损失导致铁还原为Fe²⁺。因此，气相行为与光解冷冻溶液的光谱研究结果相似。二叠氮配合物3主要通过连续损失HN₃进行碎片化，铁的氧化态不变。然而，也观察到少量的氮气损失，从而形成了铁氮化物。虽然假设在冷冻溶液中通过穆斯堡尔光谱检测到的铁氮化物配合物在氮化物的反位仍由一个叠氮配位，但在气相中观察到仍带有完整的第二个叠氮的配合物[Fe(N₃)(N₂)(cyclam)]和配位不饱和的[Fe(N₂)(cyclam-H)]。
