Heavy Pentaisopropylcyclopentadienyltriylenes and their Heterobimetallic Complexes.

A series of triylenes of the heavy group 13 elements gallium, indium and thallium, carrying the pentaisopropylcyclopentadienyl ligand is reported. The compounds were characterized in solution and in the solid-state and their donor ligand properties in heterobimetallic complexes were investigated, whereby a series of tungsten carbonyl complexes was isolated. Furthermore, a new synthetic route towards a previously described lithium-aluminum heterobimetallic dimetallocene is reported, which also enabled the isolation of a heterobimetallic polydecker of lithium and gallium.

π-Complexes Derived from Non-classical Diboriranes: Side-on vs. End-on Carbonylative Ring Expansion.

Unlike cyclopropanes, the analogous BC species (diboriranes) tend to adopt non-classical Hückel-aromatic structures with bridging moieties R between the boron atoms. The coordination of the thus generated cyclic 2e π-system to transition metals is completely unexplored. We here report that complexation of non-classical diboriranes cyclo-μ-RBDurCPh (R=H, SnMe; Dur=2,3,5,6-tetramethylphenyl) to Fe(CO) fragments allows for the carbonylative ring expansion of the BC ring to either four- or five-membered rings depending on the nature of the BRB 3-center-2-electron bond (3c2e): The H-bridged diborirane (R=H) initially reacts with Fe(CO) to the allylic π-complex with an agostic BH/Fe interaction.

Surface relief VCSELs at 670 nm with integrated polymer microlens for highly collimated fundamental-mode emission.

We demonstrate the integration of a wet-chemically etched surface relief on a vertical-cavity surface-emitting laser (VCSEL) emitting in the red spectral range for higher-order mode suppression. With this relief, fundamental-mode emission is achieved over the entire power range from threshold beyond thermal rollover. For collimation of the emitted beam, we implement polymer microlenses fabricated on-chip by a thermal reflow technique.

A lithium-aluminium heterobimetallic dimetallocene.

Homobimetallic dimetallocenes exhibiting two identical metal atoms sandwiched between two η bonded cyclopentadienyl rings is a narrow class of compounds, with representative examples being dizincocene and diberyllocene. Here we report the synthesis and structural characterization of a heterobimetallic dimetallocene, accessible through heterocoupling of lithium and aluminylene fragments with pentaisopropylcyclopentadienyl ligands. The Al-Li bond features a high ionic character and profits from attractive dispersion interactions between the isopropyl groups of the cyclopentadienyl ligands.

Tetrylene-Functionalized Si-Siliconoids.

The core expansion of metallic or metalloid clusters by the addition of further homo- or heteronuclear vertices is pivotal to the nucleation and growth of particles. The exohedral grafting of a low-valent functionality followed by endohedral incorporation have been identified as key steps. Following previous work on the Si series, we now report the synthesis and full characterization of the amidinatotetrylene-functionalized seven-vertex siliconoids SiR[E(NBu)CPh] (E = Si, Ge, Sn).

Utilizing Artificial Intelligence and Chat Generative Pretrained Transformer to Answer Questions About Clinical Scenarios in Neuroanesthesiology.

Objective: We tested the ability of chat generative pretrained transformer (ChatGPT), an artificial intelligence chatbot, to answer questions relevant to scenarios covered in 3 clinical guidelines, published by the Society for Neuroscience in Anesthesiology and Critical Care (SNACC), which has published management guidelines: endovascular treatment of stroke, perioperative stroke (Stroke), and care of patients undergoing complex spine surgery (Spine).

Methods: Four neuroanesthesiologists independently assessed whether ChatGPT could apply 52 high-quality recommendations (HQRs) included in the 3 SNACC guidelines. HQRs were deemed present in the ChatGPT responses if noted by at least 3 of the 4 reviewers.

Polyhedral Oligomeric Silsesquioxane D-(RSiO).

While smaller polyhedral oligomeric silsesquioxanes TR (POSS) are readily accessible or even commercially available, unambiguously authenticated larger systems (n>12) have barely been reported. Synthesis and isolation procedures are lengthy, and yields are often very low. Herein, we present the surprisingly straightforward and high-yielding access to the phenyl-substituted derivative of a so far only postulated second D-symmetric T isomer and with that the largest crystallographically characterized POSS cage with organic substituents.

Bis(tetrelocenes) - fusing tetrelocenes into close proximity.

We report the synthesis and structure of two bis(germanocenes) and a bis(stannocene), obtained by the reaction of unsymmetric bis(cyclopentadienyl) ligands with germanium and tin dichloride. DFT calculations show that the formation of these bis(tetrelocenes) is energetically favoured over the formation of the corresponding [1]tetrelocenophanes. In the crystal structure authenticated structural motif, the two tetrel(II) centers are forced into close proximity to each other, resulting in weak donor-acceptor interactions, according to Natural Bond Orbital (NBO) and Atoms in Molecules (AIM) analyses.

σ,π-Conjugated Bis(germylene) Adducts with NHC and CAACs.

Heavier tetrylenes attract attention for their potential in synthesis, catalysis and small molecule activation. The coordination by N-heterocyclic carbenes (NHCs) and cyclic (alkyl)(amino)carbenes (CAACs) results in substantial structural and electronic differences although typically only one of these yields stable derivatives for one and the same tetrylene. We now report both NHC- and CAAC-coordination to a bridged bis(germylene) motif.

Phosphanyl-substituted tin half-sandwich complexes.

Phosphanyl-substituted tin(ii) half sandwich complexes are reported. Due to the Lewis acidic tin center and Lewis basic phosphorous atom they form head-to-tail dimers. Their properties and reactivities were investigated both experimentally and theoretically.

Siliconoid Expansion by a Single Germanium Atom through Isolated Intermediates.

The growth of (semi-)metal clusters is pivotal for nucleation processes in gaseous and condensed phases. We now report the isolation of intermediates during the expansion of a stable unsaturated silicon cluster (siliconoid) by a single germanium atom through a sequence of substitution, rearrangement and reduction. The reaction of ligato-lithiated hexasilabenzpolarene LiSi Tip (1Li⋅(thf) , Tip=2,4,6-triisopropylphenyl) with GeCl ⋅NHC (NHC=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) initially yields the product with exohedral germanium(II) functionality, which then inserts into an Si-Si bond of the Si scaffold.

Bis(di--butylindenyl)tetrelocenes.

The synthesis and characterization of bis(di--butylindenyl) germanium(II), tin(II) and lead(II) complexes are reported, which includes the first structurally authenticated example of a bis(indenyl)germanocene. The species were studied in detail in solution and in the solid, which includes single crystal X-ray diffraction and NMR spectroscopy, as well as Mössbauer spectroscopy of the tin compound.

Re-evaluating standards of human subjects protection for sensitive health data in social media networks.

This study addresses ethical questions about conducting health science research using network data from social media platforms. We provide examples of ethically problematic areas related to participant consent, expectation of privacy, and social media networks. Further, to illustrate how researchers can maintain ethical integrity while leveraging social media networks, we describe a study that demonstrates the ability to use social media to identify individuals affected by cancer.

Transition Metal Complexes of Heavier Vinylidenes: Allylic Coordination vs Vinylidene-Alkyne Rearrangement at Nickel.

Transition metal π-allyl complexes are key reagents/intermediates of various catalytic and stoichiometric allylation reactions. We now report the first transition metal complex of a heavier allylic π-system. The η-SiGe allyl nickel complex is formally obtained by the oxidative addition of the Si-Cl bond of the heavier vinylidene [R(Cl)Si-(R)Si═(NHC)Ge:] to [Ni(COD)] (R = 2,4,6-triisopropylphenyl; NHC = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene; COD = 1,5-cyclooctadiene).

More Than Just Privacy: Using Contextual Integrity to Evaluate the Long-Term Risks from COVID-19 Surveillance Technologies.

The global coronavirus pandemic has raised important questions regarding how to balance public health concerns with privacy protections for individual citizens. In this essay, we evaluate contact tracing apps, which have been offered as a technological solution to minimize the spread of COVID-19. We argue that apps such as those built on Google and Apple's "exposure notification system" should be evaluated in terms of the contextual integrity of information flows; in other words, the appropriateness of sharing health and location data will be contextually dependent on factors such as who will have access to data, as well as the transmission principles underlying data transfer.

Bright luminescent lithium and magnesium carbene complexes.

We report on the convenient synthesis of a CNC pincer ligand composed of carbazole and two mesoionic carbenes, as well as the corresponding lithium- and magnesium complexes. Mono-deprotonation affords a rare "naked" amide anion. In contrast to the proligand and its mono-deprotonated form, tri-deprotonated -block complexes show bright luminescence, and their photophysical properties were therefore investigated by absorption- and luminescence spectroscopy.

Transition-Metal Complexes of Heavier Cyclopropenes: Non-Dewar-Chatt-Duncanson Coordination and Facile Si═Ge Functionalization.

Transition-metal complexes of cyclopropenes occur as fleeting intermediates of numerous metal-catalyzed organic transformations. A heavier analogue has now been obtained from the reaction of an NHC-stabilized silagermenylidene, bis(1,5-cyclooctadiene)nickel(0), and 1 equiv of N-heterocyclic carbene (NHC). The residual chloro functionality at the germanium end of the coordinated Ge═Si moiety of the thus formed 1-disilagermirene is easily exchanged by treatment with anionic nucleophiles, which provides access to a series of differently substituted SiGe-cyclopropenes as nickel complexes in excellent yields.

Exohedral functionalization core expansion of siliconoids with Group 9 metals: catalytic activity in alkene isomerization.

Taking advantage of pendant tetrylene side-arms, stable unsaturated Si silicon clusters (siliconoids) with the benzpolarene motif (the energetic counterpart of benzene in silicon chemistry) are successfully employed as ligands towards Group 9 metals. The pronounced σ-donating properties of the tetrylene moieties allow for sequential oxidative addition and reductive elimination events without complete dissociation of the ligand at any stage. In this manner, either covalently linked or core-expanded metallasiliconoids are obtained.

Metathesis of Ge=Ge double bonds.

The metathesis of carbon-carbon double bonds-the 'reshuffling' of their constituting carbene fragments-is a tremendously important preparative tool in industry and academia. Metathesis of heavier alkene homologues is restricted to occasional unproductive examples in phosphorus chemistry and cross-metathesis to mixed heavier alkynes. We now report the thermally induced, transition-metal-free metathesis of purpose-built unsymmetrically substituted digermenes.

The impact of the COVID-19 pandemic on people with rheumatic and musculoskeletal diseases: insights from patient-generated data on social media.

Objectives: During the COVID-19 pandemic, much communication occurred online, through social media. This study aimed to provide patient perspective data on how the COVID-19 pandemic impacted people with rheumatic and musculoskeletal diseases (RMDs), using Twitter-based patient-generated health data (PGHD).

Methods: A convenience sample of Twitter messages in English posted by people with RMDs was extracted between 1 March and 12 July 2020 and examined using thematic analysis.

Diphosphanylmetallocenes of Main-Group Elements.

Several 1,1'-diphosphanyl-substituted metallocenes of magnesium (magnesocenes) were synthesized, structurally characterized, and their reactivity and coordination chemistry were investigated. Transmetalation of these magnesocenes gives access to group 14 metallocenes (tetrelocenes), as well as to group 15 stibonocenes. These s- and p-block metallocenes represent a novel class of bis(phosphanyl) ligands, exhibiting Lewis-amphiphilic character.

Nickel-assisted complete cleavage of CO by a silylene/siliconoid hybrid under formation of an Si[double bond, length as m-dash]C enol ether bridge.

Reaction of a silylene-functionalized Si6 siliconoid with CO in the presence of catalytic quantities of a nickel(0) complex results in the complete cleavage of the CO triple bond, but preserves the Si6 scaffold with an exohedrally incorporated Si[double bond, length as m-dash]C enol ether bridge. The uncompromised cluster core emphasizes the role of the so-called benzpolarene motif as the energetic silicon pendants of benzene in carbon chemistry.

Pentamethylcyclopentadienyl-substituted hypersilylsilylene: reversible and irreversible activation of C[double bond, length as m-dash]C double bonds and dihydrogen.

Recent studies of low-valent main group species underscore their resemblance to transition metal complexes with regards to the ability to activate small molecules. Here, we report synthesis and full characterisation of the persistent (hypersilyl)(pentamethylcyclopentadienyl)silylene Cp*[(Me3Si)3Si]Si: as well as its unique reactivity. Silylene Cp*[(Me3Si)3Si]Si: activates dihydrogen to give the corresponding dihydrosilane Cp*[(Me3Si)3Si]SiH2 at particularly mild conditions as well as ethylene to afford the three-membered cyclic silirane c-Cp*[(Me3Si)3Si]Si(H2CCH2).

Chalcogen-Expanded Unsaturated Silicon Clusters: Thia-, Selena-, and Tellurasiliconoids.

Reactions of silylenes with heavier chalcogens (E) typically result in Si=E double bonds or their π-addition products. In contrast, the oxidation of a silylene-functionalized unsaturated silicon cluster (siliconoid) with Group 16 elements selectively yields cluster expanded siliconoids Si E (E=S, Se, Te) fully preserving the unsaturated nature of the cluster scaffold as evident from the NMR signatures of the products. Mechanistic considerations by DFT calculations suggest the intermediacy of a Si siliconoid with exohedral Si=E functionality.

Equilibrium Formation of Stable All-Silicon Versions of 1,3-Cyclobutanediyl.

Main group analogues of cyclobutane-1,3-diyls are fascinating due to their unique reactivity and electronic properties. So far only heteronuclear examples have been isolated. Here we report the isolation and characterization of all-silicon 1,3-cyclobutanediyls as stable closed-shell singlet species from the reversible reactions of cyclotrisilene c-Si Tip (Tip=2,4,6-triisopropylphenyl) with the N-heterocyclic silylenes c-[(CR CH )(NtBu) ]Si: (R=H or methyl) with saturated backbones.