Öffnung der Valenzschale: Ein T‐förmiges Eisen(I)‐Metalloradikal und sein Potential als Atomabstraktor

Abstract

Ein thermisch stabiler, T‐förmiger d7‐High‐Spin‐Eisen(I)‐Komplex wurde durch die Reduktion eines PNP‐stablisierten Eisen(II)‐Chlorido‐Komplexes erhalten. Paramagnetische NMR‐Spektroskopie, gekoppelt mit einer DFT‐Modellierung, ermöglichte die Analyse der elektronischen Struktur dieser koordinativ hochgradig ungesättigten Verbindung. Der Metalloradikalcharakter der Verbindung wurde durch die Bildung eines Ketyl‐Radikalkomplexes unter Versetzen mit Benzophenon gezeigt. Außerdem weist der Komplex eine reichhaltige Chemie als Sauerstoffatom‐Abstraktor von Epoxiden unter Bildung eines zweikernigen, Oxo‐verbrückten Eisen(II)‐Komplexes auf.

Cobalt and Iron Stabilized Ketyl, Ketiminyl and Aldiminyl Radical Anions

“…Interestingly, using an excess of 1,4-CHD in the presence of [2] À led, besides some C 6 H 6 , to the formation of the anionic sandwich complex [Co À I (1,3-CHD) 2 ] À , [9] À , and concomitantly [Co(NR 2 ) 3 ] À which speaks to redox and ligand rearrangement. [9] À resembles the related anthracenide or butadiene cobaltates(-I) from Ellis and co-workers (Scheme 2). [37] The presence of the ketyl ligand is thereby not necessary for the formation of [9] À as it can be directly obtained via reaction of either 1,3-or 1,4-CHD and [Co(N(SiMe 3 ) 2 ) 2 ] À .…”

“…[9] À resembles the related anthracenide or butadiene cobaltates(-I) from Ellis and co-workers (Scheme 2). [37] The presence of the ketyl ligand is thereby not necessary for the formation of [9] À as it can be directly obtained via reaction of either 1,3-or 1,4-CHD and [Co(N(SiMe 3 ) 2 ) 2 ] À . The formation of the 1,3-CHD complex [9] À is accompanied by a sigmatropic H-atom shift of 1,4-CHD.…”

“…Details concerning the syntheses of all complexe, the spectroscopic and physical properties, in situ spectroscopic data and X-ray diffraction data are given in the Supporting Information. Deposition Numbers 2093093 ([K{18c6}][1]), 2093094 ([K{18c6}] [2]), 2093095 (K {18c6} [3]), 2093096 (K{18c6}[4]), 2093097 (K{18c6} [5]), 2093086 (1), 2093087 (2), 2093088 (5), 2093089 (6), 2093090 (7), 2093091 (8), 2093098 (K{18c6} [9]), 2093099 ([K{18c6}] 2 [10]), 2093100 ([K {18c6}] 2 [11]), 2093092 (K{18c6} [12]) contain the supplementary crystallographic data for this paper. These data are provided free of charge by the joint Cambridge Crystallographic Data Centre and Fachinformationszentrum Karlsruhe Access Structures service.…”

“…[37] The presence of the ketyl ligand is thereby not necessary for the formation of [9] À as it can be directly obtained via reaction of either 1,3-or 1,4-CHD and [Co(N(SiMe 3 ) 2 ) 2 ] À . The formation of the 1,3-CHD complex [9] À is accompanied by a sigmatropic H-atom shift of 1,4-CHD. The metal bound radical anions thus intriguingly act in two roles: a) as a facilitator for HAA abstraction and b) as an electron reservoir that reversibly masks a metal(I) ion.…”

“…However, examples for metal-bound carbonyl or iminyl radical anions are scarce and mostly restricted to diaryl ketones as illustrated for the isolation of the alkali metal salts the benzophenone or fluorenone radical anion. [7,8] Few additional examples of other metal complexes bearing simple diaryl ketyl or fluorenyl radical anions were authenticated in case of transition-(Fe, Zr) [9][10][11] and rare earth metals (Sm, Eur, Yb, La) [12,[13][14][15][16] as well as uranium [17] and alkali (earth) metals. [18,19] Here, the intermolecular coupling of the substrate occurs in the absence of sufficient steric protection or blocking of susceptible substrate positions, which in rare cases is found to be reversible.…”