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Reaction of the CoI complex [(TIMMNmes)CoI](PF6) (1) (TIMMNmes=tris‐[2‐(3‐mesityl‐imidazolin‐2‐ylidene)‐methyl]amine) with mesityl azide yields the CoIII imide [(TIMMNmes)CoIII(NMes)](PF6) (2). Oxidation of 2 with [FeCp2](PF6) provides access to a rare CoIII imidyl [(TIMMNmes)Co(NMes)](PF6)2 (3). Single‐crystal X‐ray diffractometry and EPR spectroscopy confirm the molecular structure of 3 and its S=1/2 ground state. ENDOR, X‐ray absorption spectroscopy and computational analyses indicate a ligand‐based oxidation; thus, an imidyl‐radical electronic structure for 3. Migratory insertion of one ancillary NHC to the imido ligand in 2 gives the CoIN‐heterocyclic imine (4) within 12 h. Conversely, it takes merely 0.5 h for 3 to transform to the CoII congener (5). The migratory insertion in 2 occurs via a nucleophilic attack of the imido ligand at the NHC to give 4, whereas in 3, a nucleophilic attack of the NHC at the electrophilic imidyl ligand yields 5. The reactivity shunt upon oxidation of 2 to 3 confirms an umpolung of the imido ligand. [ABSTRACT FROM AUTHOR]

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=1/2 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The dinuclear zinc complex Zn2L2 (HL=2‐{[[di(2‐pyridyl)methyl](methyl)amino]methyl}phenol) has been synthesized and isolated as colorless crystals. The interaction of the compound with superoxide in anhydrous organic solvents has been evaluated by CV, stopped‐flow Uv‐vis, EPR and ESI‐MS suggesting the binding and the activation of the coordinated superoxide, thanks to the Lewis acidity of the Zn(II) centers. The results obtained in this study highlight the formation of a Zn2L2−O2.− intermediate and a metastable phenoxyl‐radical driven by the coordinated superoxide. [ABSTRACT FROM AUTHOR]

The nitrido‐ate complex [(PN)2Ti(N){μ2‐K(OEt2)}]2 (1) (PN−=(N‐(2‐PiPr2‐4‐methylphenyl)‐2,4,6‐Me3C6H2) reductively couples CO and isocyanides in the presence of DME or cryptand (Kryptofix222), to form rare, five‐coordinate TiII complexes having a linear cumulene motif, [K(L)][(PN)2Ti(NCE)] (E=O, L=Kryptofix222, (2); E=NAd, L=3 DME, (3); E=NtBu, L=3 DME, (4); E=NAd, L=Kryptofix222, (5)). Oxidation of 2–5 with [Fc][OTf] afforded an isostructural TiIII center containing a neutral cumulene, [(PN)2Ti(NCE)] (E=O, (6); E=NAd (7), NtBu (8)) and characterization by CW X‐band EPR spectroscopy, revealed unpaired electron to be metal centric. Moreover, 1e− reduction of 6 and 7 in the presence of Kryptofix222cleanly reformed corresponding discrete TiII complexes 2 and 5, which were further characterized by solution magnetization measurements and high‐frequency and ‐field EPR (HFEPR) spectroscopy. Furthermore, oxidation of 7 with [Fc*][B(C6F5)4] resulted in a ligand disproportionated TiIV complex having transoid carbodiimides, [(PN)2Ti(NCNAd)2] (9). Comparison of spectroscopic, structural, and computational data for the divalent, trivalent, and tetravalent systems, including their 15N enriched isotopomers demonstrate these cumulenes to decrease in order of backbonding as TiII→TiIII→TiIV and increasing order of π‐donation as TiII→TiIII→TiIV, thus displaying more covalency in TiIII species. Lastly, we show a synthetic cycle whereby complex 1 can deliver an N‐atom to CO and CNAd. [ABSTRACT FROM AUTHOR]

Decarbonylation along with P‐atom transfer from the phosphaethynolate anion, PCO−, to the NbIV complex [(PNP)NbCl2(NtBuAr)] (1) (PNP=N[2‐PiPr2‐4‐methylphenyl]2−; Ar=3,5‐Me2C6H3) results in its coupling with one of the phosphine arms of the pincer ligand to produce a phosphanylidene phosphorane complex [(PNPP)NbCl(NtBuAr)] (2). Reduction of 2 with CoCp*2 cleaves the P−P bond to form the first neutral and terminal phosphido complex of a group 5 transition metal, namely, [(PNP)Nb≡P(NtBuAr)] (3). Theoretical studies have been used to understand both the coupling of the P‐atom and the reductive cleavage of the P−P bond. Reaction of 3 with a two‐electron oxidant such as ethylene sulfide results in a diamagnetic sulfido complex having a P−P coupled ligand, namely [(PNPP)Nb=S(NtBuAr)] (4). [ABSTRACT FROM AUTHOR]

Decarbonylation along with P‐atom transfer from the phosphaethynolate anion, PCO−, to the NbIV complex [(PNP)NbCl2(NtBuAr)] (1) (PNP=N[2‐PiPr2‐4‐methylphenyl]2−; Ar=3,5‐Me2C6H3) results in its coupling with one of the phosphine arms of the pincer ligand to produce a phosphanylidene phosphorane complex [(PNPP)NbCl(NtBuAr)] (2). Reduction of 2 with CoCp*2 cleaves the P−P bond to form the first neutral and terminal phosphido complex of a group 5 transition metal, namely, [(PNP)Nb≡P(NtBuAr)] (3). Theoretical studies have been used to understand both the coupling of the P‐atom and the reductive cleavage of the P−P bond. Reaction of 3 with a two‐electron oxidant such as ethylene sulfide results in a diamagnetic sulfido complex having a P−P coupled ligand, namely [(PNPP)Nb=S(NtBuAr)] (4). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Drei lineare Dimere mit jeweils zwei redoxaktiven planarisierten Triphenylaminen wurden synthetisiert, und ihre Struktur wurde mittels Röntgenstrukturanalyse aufgelöst. Diese Verbindungen sind von großem Interesse, da ihre Radikalkationen einen Selbstaustausch des ungepaarten Elektrons zwischen den beiden Redoxzentren aufweisen. Dieser Prozess wurde eingehend mittels Elektronenspinresonanz‐Spektroskopie, Absorptionsspektroskopie und (zeitabhängigen) Dichtefunktionaltheorie‐Rechnungen untersucht. Ein Vergleich der Schlüsselparameter des Elektronentransfers mit nicht‐planarisierten stickstoffzentrierten Bausteinen unterstreicht den Einfluss von Redoxzentren mit niedrigen inneren Reorganisationsenergien. Hingegen bleibt der entfernungsabhängige Abschwächungsfaktor des Superaustauschmechanismus ähnlich. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Single atom (SA) catalysis, over the last 10 years, has become a forefront in heterogeneous catalysis, electrocatalysis, and most recently also in photocatalysis. Most crucial when engineering a SA catalyst/support system is the creation of defined anchoring points on the support surface to stabilize reactive SA sites. Here, a so far unexplored but evidently very effective approach to trap and stabilize SAs on a broadly used photocatalyst platform is introduced. In self‐organized anodic TiO2 nanotubes, a high degree of stress is incorporated in the amorphous oxide during nanotube growth. During crystallization (by thermal annealing), this leads to a high density of Ti3+‐Ov surface defects that are hardly present in other common titania nanostructures (as nanoparticles). These defects are highly effective for SA iridium trapping. Thus a SA‐Ir photocatalyst with a higher photocatalytic activity than for any classic co‐catalyst arrangement on the semiconductive substrate is obtained. Hence, a tool for SA trapping on titania‐based back‐contacted platforms is provided for wide application in electrochemistry and photoelectrochemistry. Moreover, it is shown that stably trapped SAs provide virtually all photocatalytic reactivity, with turnover frequencies in the order of 4 × 106 h−1 in spite of representing only a small fraction of the initially loaded SAs. [ABSTRACT FROM AUTHOR]

Black TiO2 in various forms has been investigated for numerous photochemical applications. In photocatalytic water splitting, "grey" titania forms have been reported to reach considerable H2 generation rates without using a noble metal co‐catalyst. Up to now, a variety of anatase powders or other morphologies has been investigated in grey and black forms. Here we describe that hydrothermal titanate/anatase nanotubes can show a strong noble metal free photocatalytic activity. For optimized "blackening" conditions, a drastically higher photocatalytic H2 production can be obtained than for other nanoscale morphologies. This effect can further be improved with a very mild Pt doping that again shows a clearly stronger photocatalytic H2 production than comparably loaded nanopowders. [ABSTRACT FROM AUTHOR]

Fe-HHTP-MOF is a highly crystalline, porous, and deep black material featuring high electrical conductivity. Keywords: electrical conductivity; iron-catecholate; metal-organic frameworks; porosity; three-dimensional framework EN electrical conductivity iron-catecholate metal-organic frameworks porosity three-dimensional framework 17749 17749 1 08/05/21 20210809 NES 210809 B Fe-HHTP-MOF b , a unique cubic metal-organic framework (MOF) comprising hexahydroxytriphenylene (HHTP) supertetrahedral units and Fe SP III sp ions arranged in a diamond topology, is reported by Thomas Bein, Dana D. Medina et al. in their Research Article on page 18065. Fe-HHTP-MOF is a highly crystalline, porous, and deep black material featuring high electrical conductivity. [Extracted from the article]

Keywords: electrical conductivity; iron-catecholate; metal-organic frameworks; porosity; three-dimensional framework EN electrical conductivity iron-catecholate metal-organic frameworks porosity three-dimensional framework 17893 17893 1 08/05/21 20210809 NES 210809 B Fe-HHTP-MOF b , ein einzigartiges kubisches metallorganisches Gerüst (MOF), das aus supertetraedrischen Hexahydroxytriphenylen(HHTP)-Einheiten und in Rautentopologie angeordneten Fe SP III sp -Ionen aufgebaut ist, wird im Forschungsartikel auf S. 18213 von Thomas Bein, Dana D. Medina et al. vorgestellt. GLO:OL3/09aug21:ange202106478-toc-0001.jpg PHOTO (COLOR): . gl GLO:OL3/09aug21:ange202106478-toc-0001.jpg PHOTO (COLOR): . gl B Fe-HHTP-MOF b , ein einzigartiges kubisches metallorganisches Gerüst (MOF), das aus supertetraedrischen Hexahydroxytriphenylen(HHTP)-Einheiten und in Rautentopologie angeordneten Fe SP III sp -Ionen aufgebaut ist, wird im Forschungsartikel auf S. 18213 von Thomas Bein, Dana D. Medina et al. vorgestellt. Fe-HHTP-MOF ist ein hochkristallines, poröses und tiefschwarzes Material, das eine hohe elektrische Leitfähigkeit aufweist. [Extracted from the article]