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Hirshfeld atom refinement (HAR) is a novel X-ray structure refinement technique that employs aspherical atomic scattering factors obtained from stockholder partitioning of a theoretically determined tailor-made static electron density. HAR overcomes many of the known limitations of independent atom modelling (IAM), such as too short element–hydrogen distances, r ( X —H), or too large atomic displacement parameters (ADPs). This study probes the accuracy and precision of anisotropic hydrogen and non-hydrogen ADPs and of r ( X —H) values obtained from HAR. These quantities are compared and found to agree with those obtained from (i) accurate neutron diffraction data measured at the same temperatures as the X-ray data and (ii) multipole modelling (MM), an established alternative method for interpreting X-ray diffraction data with the help of aspherical atomic scattering factors. Results are presented for three chemically different systems: the aromatic hydrocarbon rubrene (orthorhombic 5,6,11,12-tetraphenyltetracene), a co-crystal of zwitterionic betaine, imidazolium cations and picrate anions (BIPa), and the salt potassium hydrogen oxalate (KHOx). The non-hydrogen HAR-ADPs are as accurate and precise as the MM-ADPs. Both show excellent agreement with the neutron-based values and are superior to IAM-ADPs. The anisotropic hydrogen HAR-ADPs show a somewhat larger deviation from neutron-based values than the hydrogen SHADE-ADPs used in MM. Element–hydrogen bond lengths from HAR are in excellent agreement with those obtained from neutron diffraction experiments, although they are somewhat less precise. The residual density contour maps after HAR show fewer features than those after MM. Calculating the static electron density with the def2-TZVP basis set instead of the simpler def2-SVP one does not improve the refinement results significantly. All HARs were performed within the recently introduced HARt option implemented in the Olex2 program. They are easily launched inside its graphical user interface following a conventional IAM.

The reaction of the previously known bis(6-diphenylphosphinoacenaphthyl-5-)telluride (6-Ph2P-Ace-5-)2Te (IV) with (CO)5ReCl and (CO)5MnBr proceeded with the liberation of CO and provided fac-(6-Ph2P-Ace-5-)2TeM(X)(CO)3 (fac-1: M = Re, X = Cl; fac-2: M = Mn, X = Br), in which IV acts as bidentate ligand. In solution, fac-1 and fac-2 are engaged in a reversible equilibrium with mer-(6-Ph2P-Ace-5-)2TeM(X)(CO)3 (mer-1: M = Re, X = Cl; mer-2: M = Mn, X = Br). Unlike fac-1, fac-2 is prone to release another equivalent of CO to give (6-Ph2P-Ace-5-)2TeMn(Br)(CO)2 (3), in which IV serves as tridentate ligand.

The reaction of the diferrocenylphosphenium ion with four terminal allenes follows two different pathways, via allyl or vinyl carbocations, which proceed with electrophilic substitution reactions at one ferrocenyl moiety to form persistent Wheland intermediates and eventually alkenyldiferrocenylphosphonium salts. The reaction of the diferrocenylphosphenium ion with 2‐(trimethylsilyl)‐2,3‐pentadiene affords a stable Wheland intermediate of ferrocene in high yields, which is isolated and fully characterized. A kinetically stable Wheland intermediate of the electrophilic aromatic substitution at ferrocene is isolated from the reaction of the diferrocenylphosphenium ion with the allene 2‐(trimethylsilyl)‐2,3‐pentadiene and fully characterized.

Chalcogenide radical cations [R 2 E] •+ (E = S, Se, Te) are commonly short-lived intermediates of fundamental interest. Sulfide radical cations in particular are associated in vivo with oxidative stress and neuropathological processes. Having succeeded in the preparation of meta -terphenyl-based dichalcogenide radical cations [R 2 E 2 ] •+ (E = S, Se, Te), and a telluride analogue [R 2 Te] •+ in the past, we aimed to complete the series regarding sulfur and selenium. Here we report on the single-electron oxidation of diarylchalcogenides M S FluindPhE (E = S, Se, Te; M S Fluind = dispiro[fluorene-9,3’-(1’,1’,7’,7’-tetramethyl- s -hydrindacen-4’-yl)-5’,9”-fluorene]) using XeF 2 in the presence of K[B(C 6 F 5 ) 4 ], which afforded deeply coloured and isolable radical cation salts [M S FluindPhE][B(C 6 F 5 ) 4 ] (E = S, Se, Te). Structural and electronic properties were characterised by electron paramagnetic spectroscopy, cyclic voltammetry, optical absorption spectroscopy and single crystal X-ray diffraction (E = Se, Te), combined with extensive quantum mechanical computations. Chalcogenide radical cations are usually short-lived intermediates, making their isolation challenging. Here, the authors report the stabilization of these species by using the M S Fluind (dispiro[fluorene-9,3’-(1’,1’,7’,7’-tetramethyl- s -hydrindacen-4’-yl)-5’,9”-fluorene]) substituent to produce [M S FluindPhE][B(C 6 F 5 ) 4 ] (E = S, Se, Te) radical cation salts, which they characterize using electron paramagnetic spectroscopy, cyclic voltammetry, optical absorption spectroscopy, single crystal X-ray diffraction and quantum mechanical computations.

Efficient infiltration of a mesoporous titania matrix with conducting organic polymers or small molecules is one key challenge to overcome for hybrid photovoltaic devices. A quantitative analysis of the backfilling efficiency with time-of-flight grazing incidence small-angle neutron scattering (ToF-GISANS) and scanning electron microscopy (SEM) measurements is presented. Differences in the morphology due to the backfilling of mesoporous titania thin films are compared for the macromolecule poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2- b ;4,5- b ′]dithiophene-2,6-diyl- alt -(4-(2-ethylhexyl)-3-fluorothieno[3,4- b ]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7-Th) and the heavy-element containing small molecule 2-pinacolboronate-3-phenylphenanthro[9,10- b ]tellurophene (PhenTe-BPinPh). Hence, a 1.7 times higher backfilling efficiency of almost 70% is achieved for the small molecule PhenTe-BPinPh compared with the polymer PTB7-Th despite sharing the same volumetric mass density. The precise characterization of structural changes due to backfilling reveals that the volumetric density of backfilled materials plays a minor role in obtaining good backfilling efficiencies and interfaces with large surface contact.

The Front Cover shows a round‐bottomed flask containing a burgundy solution of diferrocenylphosphenium ion [Fc2P][B(C6F5)4], which was used in this work to activate various allenes. Dropwise addition to 2‐(trimethylsilyl) penta‐2,3‐diene yields a bright red solution of a stable Wheland intermediate of ferrocene, whose solid‐state structure is depicted as a ball‐and‐stick model. In front lies Saint Peter’s Key, a prominent feature of the City of Bremen’s coat of arms, representing the unlocked potential of highly reactive main group species. More information can be found in the Research Article by E. Hupf, J. Beckmann and co‐workers (DOI: 10.1002/ceur.202500031).

We report a series of dibenzyl isophthalates (DBIs) as versatile hosts for room-temperature phosphorescence (RTP) systems, leading to host-guest systems with quantum yields (QY) of up to 77 % or lifetimes of up to 21.0 s for the guest coronene d12. Furthermore, a 4,4’-Br substituted DBI was used to form host-guest RTP systems with 15 different aromatic guest molecules, to tune the phosphorescence emission color from blue to red and to demonstrate the versatility of the host. Mechanistic insights were gained through a host-guest-matrix system which shows RTP already by trace combinations of a 4,4’ Br DBI host (0.10 wt%) and a pyrene-d10 guest (0.01 wt%) in an otherwise non-RTP-emissive aromatic matrix