Decacyclene as Complexation Manifold: Synthesis, Structure and Properties of Its Fe₂ and Fe₄ Slipped Triple‐Decker Complexes

Abstract

Reaction of [(eta(5)-Me4EtC5)Fe(II)Cl(tmeda)] (tmeda = N,N,N'N'-tetramethylethylenediamine) with a polyanion solution of decacyclene (1) results in the formation of the triple-deckers [{(eta(5)-Me4EtC5)Fe}2-mu2-(eta(6):eta(6)-decacyclene)] (3) and [{(eta(5)-Me4EtC5)Fe}4-mu4-(eta(6):eta(6):eta(6):eta(6)-decacyclene)] (4). Metal complexation in 3 and 4 occurs on opposite faces of the pi perimeter in an alternating mode. The decacyclene ring adopts a gently twisted molecular propeller geometry with twofold crystallographic symmetry (C2). Complex 4 crystallizes in the chiral space group C222(1); the investigated crystal only contains decacyclene rings with M chirality. The handedness can be assigned unambiguously to the presence of the iron atoms. Cyclovoltammetric studies revealed quasireversible behavior of the redox events and a strong interaction of the Fe atoms in 3 and 4, exemplified by potential differences deltaE of 660 and 770(780) mV between the first and the second individual oxidation processes. This corresponds to a high degree of metal-metal interaction for 3 and 4. The successful syntheses of 3 and 4 together with earlier results from our laboratory proves that all five- and six-membered pi subunit sets of 1 are prone to metal complexation. A clear site preference in 1 towards the complexation of [Cp(R)]iron, -cobalt, and -nickel fragments exists.

C−H Bond Activation of Heteroarenes Mediated by a Half-Sandwich Iron Complex of N-Heterocyclic Carbene

“…Their molecular structures are very similar, and Figure shows only an ORTEP drawing of 2a , while selected bond distances and angles for 2a and 2b are given in the figure caption. These are coordinatively unsaturated half-sandwich 16e complexes, and the Fe−Cl distances of 2a and 2b are shorter by 0.02−0.10 Å than those of analogous 18e complexes of iron . While numerous half-sandwich iron complexes have been crystallographically characterized, those with 16 electrons are still limited .…”

ChemInform Abstract: An Oxidative Coupling for the Synthesis of Arylated Quaternary Stereocenters and Its Application in the Total Synthesis of Powelline and Buphanidrine.

“…Reduction of metal halides with polyarenemetalates has proven to be useful to synthesize polyarene complexes of low‐valent metals,8 and this procedure has been applied to prepare di‐ to tetranuclear iron complexes of decacyclene (C 36 H 18 )9 and a {(Cp*)Fe 0 } naphthalene complex [K([18]crown‐6){Cp*Fe(η 4 ‐C 10 H 8 )}] 10. Expecting similar chemistry, we treated [FeCl(Cp*)(tmeda)] ( 1 ; TMEDA= N , N , N′ , N′ ‐tetramethylethylenediamine)11 with potassium naphthalenide (KC 10 H 8 ) in tetrahydrofuran (THF) to give a dark‐green solution, from which a dinuclear Fe I Fe I complex with a bridging naphthalene, 2 , was isolated as dark‐green crystals in 40 % yield (Scheme…”

High‐Yielding Synthesis and Full Spectroscopic Characterization of 5,6:11,12‐Di‐o‐phenylenetetracene and Its Synthesis Intermediates

“…For instance, we have already identified a systematic coordination scheme for the PAH decacyclene, depending on the coordinating metalligand fragments introduced. [7][8][9] We found that metal coordination occurs at those positions that result in the highest aromaticity for the remaining conjugated PAH fragment of the parent hydrocarbon. According to these results, a preferred coordination to the peripheral phenylene groups is expected for DOPT and will be a focus of future studies.…”

“…[7][8][9][10][11] The extended conjugation of the title molecule in an isolated yield of >70 %. Re-aromatization of the annulated π-ring system occurred following the reductive elimination of the two phenyl groups from the DOPT precursor.…”

“…Our previous studies in the field of organometallic chemistry of polycondensed aromatics focused on the reactions of PAH anion (PAH [7] as well as cobalt and nickel, for example, [ [8,9] Our attention was drawn to the coordination behavior and electron-transfer characteristics of the resulting multidecker metal complexes. [7][8][9][10][11] The extended conjugation of the title molecule in an isolated yield of >70 %.…”