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As key intermediates in metal-catalyzed nitrogen-transfer chemistry, terminal imido complexes of iron have attracted significant attention for a long time. In search of versatile model compounds, the recently developed second-generation

Employing the newly developed, hepta-dentate tris(aryloxide) ligand cyclen(Me)(t-Bu,t-BuArOH)3 provides controlled access to the first U(iv/v) hydroxido and U(iv/v/vi) oxido complex pairs in a retained ligand environment.

Novel cobalt and zinc complexes with the tetradentate ppq (8-(1″,10″-phenanthrol-2″-yl)-2-(pyrid-2'-yl)quinoline) ligand have been synthesized and fully characterized. Electrochemical measurements have shown that the formal monovalent complex [Co(ppq)(PPh3)]+ (2) undergoes two stepwise ligand-based electroreductions in DMF, affording a [Co(ppq)DMF]-1 species. Theoretical calculations have described the electronic structure of [Co(ppq)DMF]-1 as a low-spin Co(II) center coupling with a triple-reduced ppq radical ligand. In the presence of triethylammonium as the proton donor, the cobalt complex efficiently drives electrocatalytic hydrogen evolution with a maximum turnover frequency of thousands per second. A mechanistic investigation proposes an EECC H2-evolving pathway, where the second ligand-based redox process (E), generating the [Co(ppq)DMF]-1 intermediate, initiates proton reduction, and the second proton transfer process (C) is the rate-determining step. This work provides a unique example for understanding the role of redox-active ligands in electrocatalytic H2 evolution by transition metal sites.

Octahedral coordination complexes of the general formula trans-[MX2(R2ECH2CH2ER2)2] (MII = Ti, V, Cr, Mn; E = N, P; R = alkyl, aryl) are a cornerstone of both coordination and organometallic chemistry, and many of these complexes are known to have unique electronic structures that have been incompletely examined. The trans-[CrCl2(dmpe)2] complex (dmpe = Me2PCH2CH2PMe2), originally reported by Girolami and co-workers in 1985, is a rare example of a six-coordinate d4 system with an S = 1 (spin triplet) ground state, as opposed to the high-spin (S = 2, spin quintet) state. The ground-state properties of S = 1 systems are challenging to study using conventional spectroscopic methods, and consequently, the electronic structure of trans-[CrCl2(dmpe)2] has remained largely unexplored. In this present work, we have employed high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy to characterize the ground-state electronic structure of trans-[CrCl2(dmpe)2]. This analysis yielded a complete set of spin Hamiltonian parameters for this S = 1 complex: D = +7.39(1) cm-1, E = +0.093(1) (E/D = 0.012), and g = [1.999(5), 2.00(1), 2.00(1)]. To develop a detailed electronic structure description for trans-[CrCl2(dmpe)2], we employed both classical ligand-field theory and quantum chemical theory (QCT) calculations, which considered all quintet, triplet, and singlet ligand-field states. While the high density of states suggests an unexpectedly complex electronic structure for this "simple" coordination complex, both the ligand-field and QCT methods were able to reproduce the experimental spin Hamiltonian parameters quite nicely. The QCT computations were also used as a basis for assigning the electronic absorption spectrum of trans-[CrCl2(dmpe)2] in toluene.

Iron compounds containing a bridging oxo or sulfido moiety are ubiquitous in biological systems, but substitution with the heavier chalcogenides selenium and tellurium, however, is much rarer, with only a...

Decarbonylation along with P-atom transfer from the phosphaethynolate anion, PCO

The synthesis of a tripodal, S-based ligand, namely the mesitylene-anchored, tris-thiophenolate-functionalized (mes(Me,AdArS)3)3- (1)3-, and its coordination chemistry with low-valent uranium to form [UIII((SArAd,Me)3mes)] (1-U) are reported. Single-crystal X-ray diffraction analysis reveals a C3-symmetric molecular structure. Full characterization of 1-U was performed using nuclear magnetic resonance, UV-vis-NIR electronic absorption, and electron paramagnetic resonance spectroscopies as well as SQUID magnetometry, thus confirming the U(III) oxidation state. Alternating current magnetic studies show that 1-U exhibits single-molecule magnet behavior at low temperatures in a non-zero external field. Comparison of these results to those of the previously reported mesitylene-anchored complexes, [UIII((OArAd,Me)3mes)] and [UIII((OArtBu,tBu)3mes)], indicates a drastic change in the electronic structure when moving from phenolate-based ligands to thiophenolate-based 1, which is further discussed by means of computational analysis (NBO, DFT, and QTAIM). Despite the U-O bonds being stronger, a much higher covalency was found for the U-S analogue.

The facile synthesis of the first bis‐N‐heterocyclic imine‐stabilized chlorosilyliumylidene 1 is reported. Remarkably, consecutive reaction of 1 with PPh3AuCl and K2Fe(CO)4 gives rise to the unique heterobimetallic complex 1,2‐(MesNHI)2‐C2H4‐ClSiAuFe(CO)4 (4). The overall neutral complex 4 bears an unusual linear Si−Au−Fe structure and a rare anagostic interaction between the d 10‐configured gold atom and a CH bond of the mesityl ligand. According to the computational analysis and 57Fe Mössbauer spectroscopy, the formal Fe‐oxidation state remains at −II. Thus, the electronic structure of 4 is best described as an overall neutral—yet zwitterionic—heterobimetallic “Si(II)+‐Au(I)+‐Fe(‐II)2−”‐silyliumylidene complex, derived from double anion exchange. The computational analysis indicates strong hyperconjugative back donation from the gold(I) atom to the silyliumylidene ligand., The selective synthesis of a silyliumylidene‐stabilized mononuclear Au−Fe complex, by a convenient one‐pot reaction starting from bis‐NHI silyliumylidene chloride, is reported. X‐ray crystallography, IR and 57Fe Mössbauer spectroscopy, as well as computations suggest a zwitterionic Si(II)+−Au(I)+−Fe(‐II)2− bonding motif with rare anagostic CH⋅⋅⋅Au contacts and considerable backbonding capabilities of the silyliumylidene.

With a view to developing multimetallic molecular catalysts that mimic the oxygen‐evolving catalyst (OEC) in Nature's photosystem II, the synthesis of various dicubanoid manganese clusters is described and their catalytic activity investigated for water oxidation in basic, aqueous solution. Pyridinemethanol‐based ligands are known to support polynuclear and cubanoid structures in manganese coordination chemistry. The chelators 2,6‐pyridinedimethanol (H2L1) and 6‐methyl‐2‐pyridinemethanol (HL2) were chosen to yield polynuclear manganese complexes; namely, the tetranuclear defective dicubanes [MnII 2MnIII 2(HL1)4(OAc)4(OMe)2] and [MnII 2MnIII 2(HL1)6(OAc)2] (OAc)2⋅2 H2O, as well as the octanuclear‐dicubanoid [MnII 6MnIII 2(L2)4(O)2(OAc)10(HOMe/OH2)2]⋅3MeOH⋅MeCN. In freshly prepared solutions, polynuclear species were detected by electrospray ionization mass spectrometry, whereas X‐band electron paramagnetic resonance studies in dilute, liquid solution suggested the presence of divalent mononuclear Mn species with g values of 2. However, the magnetochemical investigation of the complexes’ solutions by the Evans technique confirmed a haphazard combination of manganese coordination complexes, from mononuclear to polynuclear species. Subsequently, the newly synthesized and characterized manganese molecular complexes were employed as precursors to prepare electrode‐deposited films in a buffer‐free solution to evaluate and compare their stability and catalytic activity for water oxidation electrocatalysis., Film star: Cubanoid tetranuclear and octanuclear manganese complexes are synthesized and electrodeposited on an active surface to compare their electrocatalytic activity for the water oxidation reaction. A simple, direct relationship is derived between the manganese content in the precursor and the oxygen evolution activity of the deposited films.

Oxidation of the low-spin FeIV imido complex [{(tBupyrr)2py}Fe═NAd] (1) ((tBupyrr)2py2- = 2,6-bis(3,5-di-tert-butyl-pyrrolyl)pyridine, Ad = 1-adamantyl) with AgOAc or AgNO3 promotes reductive N-N bond coupling of the former imido nitrogen with a pyrrole nitrogen to form the respective ferric hydrazido-like pincer complexes [{(tBupyrrNAd)(tBupyrr)py}Fe(κ2-X)] (X = OAc-, 2OAc; NO3-, 2NO3). Reduction of 2OAc with KC8 cleaves the N-N bond to reform the FeIV imido ligand in 1, whereas acid-mediated demetalation of 2OAc or 2NO3 yields the free hydrazine ligand [(tBupyrrNHAd)(tBupyrrH)py] (3), the latter of which can be used as a direct entry to the iron imido complex when treated with [Fe{N(SiMe3)2}2]. In addition to characterizing these Fe systems, we show how this nitrene transfer strategy can be expanded to Co for the one-step synthesis of Co{(tBu-NHAdpyrr)(tBupyrr)py}] (4) ((tBu-NHAdpyrr)(tBupyrr)py2- = 2-(3-tBu-5-(1-adamantylmethyl-2-methylpropane-2-yl)-pyrrol-2-yl)-6-(3,5-tBu2-pyrrol-2-yl)-pyridine).

In recent years, the defect engineering of titania via reduction treatments has shown a high potential for enabling efficient and co-catalyst-free photocatalytic H2 generation from methanol/water solutions. However, defect engineering simultaneously alters several properties of TiO2. Here, we use pristine (white) and hydrogenated (gray) anatase nanosheets with dominant (001) facets. By comparing electrical conductivity, photocurrent spectra, transient photocurrent response, and photocatalytic H2 evolution, we show that the increased conductivity or broad visible light absorption of gray titania is not responsible for its increased activity. Instead, the true bottleneck is the hole transfer rate that is significantly accelerated while using gray instead of white modification. Moreover, the hole transfer reaction causes the accumulation of the reaction products in pure water, hindering the photocatalytic H2 evolution over time. These combined factors explain the superior performance of gray titania over white titania in photoelectrochemical or photocatalytic water splitting.

The present study provides a strategy for the determination of the viscosity and surface tension of high-viscosity fluids in the form of ionic liquids (ILs) at equilibrium conditions by combining surface light scattering (SLS) and the pendant-drop (PD) method within one experimental setup. Through the study of the same sample under identical conditions by both methods inside a closed system, the surface tension determined via the PD method can be directly used to evaluate the dynamics of surface fluctuations of ILs with an overdamped behavior probed by SLS for accessing their viscosity. In connection with the SLS experiments, variations in the applied detection geometries in reflection and transmission direction and in the probed wave vectors down to relatively small values were also addressed. The reliability and self-consistency of SLS and the PD method applied within the same sample cell has been proven by investigating the reference fluids tris(2-ethylhexyl) trimellitate (TOTM) and n-dodecane featuring relatively high and low viscosities. For the two studied model ILs of opaque to non-transparent color, i.e., the hydrophobic 1-methyl-3-octylimidazolium hexafluorophosphate ([OMIM][PF6]) and the hydrophilic 1,3-bis(2-(2-methoxyethoxy)ethyl)imidazolium iodide ([(mPEG2)2Im]I), the combination of PD measurements and SLS experiments in reflection direction performed at ambient pressure between (303 and 373) K allowed access to the viscosity and surface tension with typical relative expanded uncertainties of (4 and 2) %. These results agree well with own viscosity data from capillary viscometry and experimental data in the literature, demonstrating the performance of the novel approach for the contactless in-situ measurement of viscosity and surface tension of fluids with relatively high-viscosity such as ILs.

The "metathesis reaction" is a straightforward and often metal-catalyzed chemical reaction that transforms two hydrocarbon molecules to two new hydrocarbons by exchange of molecular fragments. Alkane, alkene and alkyne metathesis have become an important tool in synthetic chemistry and have provided access to complex organic structures. Since the discovery of industrial olefin metathesis in the 1960s, many modifications have been reported; thus, increasing scope and improving reaction selectivity. Olefin metathesis catalysts based on high-valent group six elements or Ru(IV) have been developed and improved through ligand modifications. In addition, significant effort was invested to realize olefin metathesis with a non-toxic, bio-compatible and one of the most abundant elements in the earth ' s crust; namely, iron. First evidences suggest that low-valent Fe(II) complexes are active in olefin metathesis. Although the latter has not been unambiguously established, this review summarizes the key advances in the field and aims to guide through the challenges., Chemistry - A European Journal, 28 (62), ISSN:0947-6539, ISSN:1521-3765

We describe a new type of nitrogen‐centered polycyclic scaffold comprising a unique combination of 5‐, 6‐, and 7‐membered rings. The compound is accessible through an intramolecular oxidative cyclodehydrogenation of tri(1‐naphthyl)amine. To the best of our knowledge this is the very first example of a direct 3‐fold cyclization of a triarylamine under oxidative conditions. The unusual ring fusion motif is confirmed by X‐ray crystallography and the impact of cyclization on the electronic and photophysical properties is investigated both experimentally and theoretically based on density‐functional theory (DFT) calculations. The formation of the unexpected product is rationalized by detailed mechanistic studies on the DFT level. The results suggest the cyclization to occur under kinetic control via a dicationic mechanism.

We report a series of uranium complexes stabilized by the pentakis-benzyl-derivatized cyclopentadienyl ligand, CpBn5. Treatment of [UCl4] and [UI3(1,4-dioxane)1,5] with 2 equiv of the potassium salt, CpBn5K, yielded the corresponding complexes [(CpBn5)2UIV(Cl)2] (1) and [(CpBn5)2UIII(I)] (4). Subsequently, tetravalent 1 is either methylated to give [(CpBn5)2UIV(Me)2] (2) or reduced to form trivalent [(CpBn5)2UIII(μ-Cl)2K(OEt2)3] (3). Oxidation of 4 with AgI yields [(CpBn5)2UIV(I)2] (5), which was found to generate rarely observed, linear uranium metallocenes [(CpBn5)2UIV(NCMe)5][X]2 (X = PF6– (6), BPh4– (7)) upon abstraction of the iodide ligands with thallium salts in acetonitrile. All complexes were characterized by 1H NMR spectroscopy, CHN elemental analysis, UV–vis–NIR spectroscopy, and SQUID magnetization measurements. The solid-state molecular structures of 1–7 were determined by single-crystal X-ray diffraction analysis. An in-depth computational analysis revealed the peculiar electronic structure of the linearly coordinated title complex 7 and its closely related, parent [(Cp*)2UIV(NCMe3)5]2+ dication.

Die Umsetzung des CoI-Komplexes [(TIMMNmes)CoI](PF6) (1) (TIMMNmes=tris-[2-(3-Mesityl-imidazolin-2-yliden)-methyl]amin) mit Mesitylazid ergibt das CoIII-Imid [(TIMMNmes)CoIII(NMes)](PF6) (2). Folgende Oxidation mit [FeCp2](PF6) ermöglicht den Zugang zu dem seltenen CoIII-Imidylkomplex [(TIMMNmes)Co(NMes)](PF6)2 (3). Einkristall-Röntgenstrukturanalyse und ESR-Spektroskopie bestätigen die molekulare Struktur von 3 und seinen S=urn:x-wiley:00448249:media:ange202206848:ange202206848-math-0001 Grundzustand. ENDOR, Röntgenabsorptionsspektroskopie und quantenchemische Rechnungen belegen eine ligandenbasierte Oxidation und damit eine Imidyl-radikalische elektronische Struktur für 3. Die Insertion einer verfügbaren NHC-Einheit in den Imidoliganden in 2 ergibt innerhalb 12 Stunden das CoI-N-heterocyclische Imin 4. Im Gegensatz dazu dauert es nur eine halbe Stunde, bis sich 3 in das CoII-Kongener 5 umsetzt. Es wurde weiterhin festgestellt, dass die Insertionsreaktion von 2 zu 4 durch einen nukleophilen Angriff des Imidoliganden am NHC erfolgt, wohingegen sich 3 zu 5 durch einen nukleophilen Angriff des NHCs am elektrophilen Imidylliganden umsetzt. Der Reaktivitätswechsel bei der Oxidation von 2 zu 3 bestätigt eine Umpolung des Imidoliganden.

We report the synthesis of a unique cubic metal–organic framework (MOF), Fe‐HHTP‐MOF, comprising hexahydroxytriphenylene (HHTP) supertetrahedral units and FeIII ions, arranged in a diamond topology. The MOF is synthesized under solvothermal conditions, yielding a highly crystalline, deep black powder, with crystallites of 300–500 nm size and tetrahedral morphology. Nitrogen sorption analysis indicates a highly porous material with a surface area exceeding 1400 m2 g−1. Furthermore, Fe‐HHTP‐MOF shows broadband absorption from 475 up to 1900 nm with excellent absorption capability of 98.5 % of the incoming light over the visible spectral region. Electrical conductivity measurements of pressed pellets reveal a high intrinsic electrical conductivity of up to 10−3 S cm−1. Quantum mechanical calculations predict Fe‐HHTP‐MOF to be an efficient electron conductor, exhibiting continuous charge‐carrier pathways throughout the structure., Fe‐HHTP‐MOF, a unique cubic metal–organic framework (MOF) comprising hexahydroxytriphenylene (HHTP) supertetrahedral units and FeIII ions arranged in a diamond topology is reported. Fe‐HHTP‐MOF is a highly crystalline, porous and deep black material featuring high electrical conductivity.

Constructing synthetic models of the nitrogenase PN -cluster has been a long-standing synthetic challenge. Here, we report an optimal nitrogenase PN -cluster model [{(TbtS)(OEt2 )Fe4 S3 }2 (μ-STbt)2 (μ6 -S)] (2) [Tbt=2,4,6-tris{bis(trimethylsilyl)methyl}phenyl] that is the closest synthetic mimic constructed to date. Of note is that two thiolate ligands and one hexacoordinated sulfide are connecting the two Fe4 S3 incomplete cubanes similar to the native PN -cluster, which has never been achieved. Cluster 2 has been characterized by X-ray crystallography and relevant physico-chemical methods. The variable temperature magnetic moments of 2 indicate a singlet ground state (S=0). The Mossbauer spectrum of 2 exhibits two doublets with an intensity ratio of 3:1, which suggests the presence of two types of iron sites. The synthetic pathway of the cluster 2 could indicate the native PN -cluster maturation process as it has been achieved from the Fe4 S4 cubane Fe4 S4 (STbt)4 (1).

The reaction of the cobalt(I) complex [(TIMMNmes)CoI](BPh4) (2) (TIMMNmes=tris‐[2‐(3‐mesitylimidazolin‐2‐ylidene)methyl]amine) with 1‐adamantylazide yields the cobalt(III) imido complex [(TIMMNmes)CoIII(NAd)](BPh4) (3) with concomitant release of dinitrogen. The N‐anchor in diamagnetic 3 features an unusual, planar tertiary amine, which results from repulsive electrostatic interaction with the filled d(z2)‐orbital of the cobalt ion and negative hyperconjugation with the neighboring methylene groups. One‐electron oxidation of 3 with [FeCp2](OTf) provides access to the rare, high‐valent cobalt(IV) imido complex [(TIMMNmes)CoIV(NAd)](OTf)2 (4). Despite a half‐life of less than 1 h at room temperature, 4 could be isolated at low temperatures in analytically pure form. Single‐crystal X‐ray diffractometry and EPR spectroscopy corroborate the molecular structure and the d5 low‐spin, S=1/2 , electron configuration. A computational analysis of 4 suggests high covalency within the CoIV=NAd bond with non‐negligible spin density located at the imido moiety, which translates into substantial triplet nitrene character., Straightforward access to a cobalt(IV) terminal imido complex was provided by one‐electron oxidation of a cobalt(III) terminal imido precursor. The cobalt(IV) monoimido complex could be isolated at low temperatures in analytically pure form. Single‐crystal X‐ray diffractometry and EPR spectroscopy corroborate the molecular structure and the d5 low‐spin, S=1/2 , electron configuration.

Molecules with different resonance structures of similar importance, such as heterocumulenes and mesoionics, are prominent in many applications of chemistry, including ‘click chemistry’, photochemistry, switching and sensing. In coordination chemistry, similar chameleonic/schizophrenic entities are referred to as ambidentate/ambiphilic or cooperative ligands. Examples of these had remained, for a long time, limited to a handful of archetypal compounds that were mere curiosities. In this Review, we describe ambiphilicity — or, rather, ‘charge frustration’ — as a general guiding principle for ligand design and functional group transfer. We first give a historical account of organic zwitterions and discuss their electronic structures and applications. Our discussion then focuses on zwitterionic ligands and their metal complexes, such as those of ylidic and redox-active ligands. Finally, we present new approaches to single-atom transfer using cumulated small molecules and outline emerging areas, such as bond activation and stable donor–acceptor ligand systems for reversible 1e− chemistry or switching. Charge-separated organic molecules find diverse applications as functional materials. This Review describes zwitterionicity as a general design principle for ‘smart’ coordination chemistry and the activation of strong bonds.

International audience; Treatment of the U(III) complex, [(C5Me5)(2)U(OMes)(THF)], Mes = 2,4,6-Me3C6H2, with Fe(CO)(5) forms [{(C5Me5)(2)(MesO)U}(2)(mu(2)-(OC)(2)Fe(CO)(2))] with the bridging, tetrahedral Fe(CO)(4) moiety. This complex has been studied using H-1 NMR, IR vibrational, UV-vis electronic absorption, and zero-field Fe-57 Mossbauer spectroscopy as well as single-crystal X-ray diffraction analysis, magnetic measurements, and DFT calculations.

Lithium trimethylsilyldiazomethanide and a cobalt (II) precursor with an N-anchored tris-NHC (TIMENmes ) ligand provide access to the cobalt nitrilimide 1. Complex 1 was structurally characterized by single-crystal X-ray diffractometry (SC-XRD) and its electronic structure was examined in detail, including EPR spectroscopy, SQUID magnetometry and computational analyses. The desilylation of the C-(trimethylsilyl)nitrilimide reveals a transient complex with an elusive diazomethanediide ligand, which substitutes one of the mesitylene rings of the ancillary ligand through C-N bond cleavage. This transformation results in the cyclometalated cobalt(II) complex 2, featuring a rare isocyanoamido-κ-C ligand.

Lithium trimethylsilyldiazomethanide and a cobalt (II) precursor with an N‐anchored tris‐NHC (TIMENmes) ligand provide access to the cobalt nitrilimide 1. Complex 1 was structurally characterized by single‐crystal X‐ray diffractometry (SC‐XRD) and its electronic structure was examined in detail, including EPR spectroscopy, SQUID magnetometry and computational analyses. The desilylation of the C‐(trimethylsilyl)nitrilimide reveals a transient complex with an elusive diazomethanediide ligand, which substitutes one of the mesitylene rings of the ancillary ligand through C−N bond cleavage. This transformation results in the cyclometalated cobalt(II) complex 2, featuring a rare isocyanoamido‐κ‐C ligand., Trimethylsilylium abstraction from a cobalt nitrilimide complex generates a transient cobalt diazomethanediide complex, which forms a terminal isocyanoamido ligand through a radical de‐arylation.

Three linear dimers with two redox‐active planarized triphenylamines were synthesized and their structures verified by X‐ray crystallography. Their radical cations, which exhibit electron self‐exchange between the two redox centers, are of great interest. This process was thoroughly investigated by means of electron paramagnetic resonance spectroscopy, absorption spectroscopy, and (time‐dependent) density functional theory calculations. A comparison of the key parameters of electron transfer with non‐planarized nitrogen‐centered building blocks emphasizes the impact of using redox centers with low internal reorganization energies. However, the distance‐dependence attenuation factor of the super‐exchange mechanisms remains similar., Novel building blocks for mixed‐valence charge‐transfer compounds: Planar N‐heterotriangulene dimers with low reorganization energies and activation barriers for electron self‐exchange have been synthesized and characterized.

We report high‐valent iron complexes supported by N‐heterocyclic carbene (NHC)‐anchored, bis‐phenolate pincer ligands that undergo ligand‐to‐metal charge transfer (LMCT) upon photoexcitation. The resulting excited states – with a lifetime in the picosecond range – feature a ligand‐based, mixed‐valence system and intense intervalence charge transfer bands in the near‐infrared region. Upon oxidation of the complex, corresponding intervalence charge transfer absorptions are also observed in the ground state. We suggest that the spectroscopic hallmarks of such LMCT states provide useful tools to decipher excited‐state decay mechanisms in high‐valent NHC complexes. Our observations further indicate that NHC‐anchored, bis‐phenolate pincer ligands are not sufficiently strong donors to prevent the population of excited metal‐centered states in high‐valent iron complexes.

Reaction of the 6π-electron aromatic four-membered heterocycle (IPr)2C2P2 (1) (IPr=1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene) with [Fe2CO9] gives the neutral iron tricarbonyl complex [Fe(CO)3-η3-{(IPr)2C2P2}] (2). Oxidation with two equivalents of the ferrocenium salt, [Fe(Cp)2](BArF24), affords the dicationic tricarbonyl complex [Fe(CO)3-η4-{(IPr)2C2P2}](BArF24)2 (4). The one-electron oxidation proceeds under concomitant loss of one CO ligand to give the paramagnetic dicarbonyl radical cation complex [Fe(CO)2-η4-{(IPr)2C2P2}](BArF24) (5). Reduction of 5 allows the preparation of the neutral dicarbonyl complex [Fe(CO)2-η4-{(IPr)2C2P2}] (6). An analysis by various spectroscopic techniques (57Fe Mössbauer, EPR) combined with DFT calculations gives insight into differences of the electronic structure within the members of this unique series of iron carbonyl complexes, which can be either described as electron precise or Wade–Mingos clusters., Angewandte Chemie. International Edition, 61 (43), ISSN:1433-7851, ISSN:1521-3773, ISSN:0570-0833

Using the potentially tridentate

The open-shell iron pentacarbonyl cation [Fe(CO)

Transmetallation of [VCl

Reaction of the Co