Unravelling White Phosphorus: Experimental and Computational Studies Reveal the Mechanisms of P4 Hydrostannylation.

The hydrostannylation of white phosphorus (P4) allows this crucial industrial precursor to be easily transformed into useful P1 products via direct, 'one pot' (or even catalytic) procedures. However, a thorough mechanistic understanding of this transformation has remained elusive, hindering attempts to use this rare example of successful, direct P4 functionalization as a model for further reaction development. Here, we provide a deep and generalizable mechanistic picture for P4 hydrostannylation by combining DFT calculations with in situ31P NMR reaction monitoring and kinetic trapping of previously unobservable reaction intermediates using bulky tin hydrides. The results offer important insights into both how this reaction proceeds and why it is successful and provide implicit guidelines for future research in the field of P4 activation.

A Novel Approach to Measuring an Old Construct: Aligning the Conceptualisation and Operationalisation of Cognitive Flexibility.

A successful adjustment to dynamic changes in one's environment requires contingent adaptive behaviour. Such behaviour is underpinned by cognitive flexibility, which conceptually is part of fluid intelligence. We argue, however, that conventional approaches to measuring fluid intelligence are insufficient in capturing cognitive flexibility. We address the discrepancy between conceptualisation and operationalisation by introducing two newly developed tasks that aim at capturing within-person processes of dealing with novelty. In an exploratory proof-of-concept study, the two flexibility tasks were administered to 307 university students, together with a battery of conventional measures of fluid intelligence. Participants also provided information about their Grade Point Averages obtained in high school and in their first year at university. We tested (1) whether an experimental manipulation of a requirement for cognitive inhibition resulted in systematic differences in difficulty, (2) whether these complexity differences reflect psychometrically differentiable effects, and (3) whether these newly developed flexibility tasks show incremental value in predicting success in the transition from high school to university over conventional operationalisations of fluid intelligence. Our findings support the notion that cognitive flexibility, when conceptualised and operationalised as individual differences in within-person processes of dealing with novelty, more appropriately reflects the dynamics of individuals' behaviour when attempting to cope with changing demands.

Methyl Methacrylate Copolymer with Pendant Thioxanthenone Groups as Active Layer for Resistive Memory Devices.

An electro-active copolymer of methyl methacrylate and 2-((4-acroylpiperazine-1-yl)methyl)-9H-thioxanthene-9-one (poly(MMA-co-ThS)) was synthesized by radical polymerization. The copolymer has good solubility in most organic solvents, thermal stability up to 282 °C and excellent ability to form thin films on silicon wafers. Poly(MMA-co-ThS) films exhibited an electrochemical and electrochromic activity resulting in the formation of long-lived radical anion states of pendant thioxanthone groups inside the film. These states exhibit optical transitions in the visible region as a broad optical absorption band, 500 < l < 900 nm (1.38

Synthesis of a stable crystalline nitrene.

Nitrenes are a highly reactive, yet fundamental, compound class. They possess a monovalent nitrogen atom and usually a short life span, typically in the nanosecond range. Here, we report on the synthesis of a stable nitrene by photolysis of the arylazide MSFluindN3 (1), which gave rise to the quantitative formation of the arylnitrene MSFluindN (2) (MSFluind is dispiro[fluorene-9,3'-(1',1',7',7'-tetramethyl-s-hydrindacen-4'-yl)-5',9''-fluorene]) that remains unchanged for at least 3 days when stored under argon atmosphere at room temperature. The extraordinary life span permitted the full characterization of 2 by single-crystal x-ray crystallography, electron paramagnetic resonance spectroscopy, and superconducting quantum interference device magnetometry, which supported a triplet ground state. Theoretical simulations suggest that in addition to the kinetic stabilization conferred by the bulky MSFluind aryl substituent, electron delocalization across the central aromatic ring contributes to the electron stabilization of 2.

1,2,3,4-Tetrafluorobiphenylene: A Prototype Janus-Headed Scaffold for Ambipolar Materials.

The title compound was synthesized by Ullmann cross-coupling in low yield as the first representative of [n]phenylene containing hydrocarbon and fluorocarbon rings. Stille/Suzuki-Miyaura cross-coupling reactions, as well as substitution of fluorine in suitable starting compounds, failed to give the same product. The geometric and electronic structures of the title compound were studied by X-ray diffraction, cyclic voltammetry and density functional theory calculations, together with Hirshfeld surface and reduced density gradient analyses. The crystal structure features head-to-tail π-stacking and other fluorine-related secondary bonding interactions. From the nucleus-independent chemical shifts descriptor, the four-membered ring of the title compound is antiaromatic, and the six-membered rings are aromatic. The Janus molecule is highly polarized; and the six-membered fluoro- and hydrocarbon rings are Lewis π-acidic and π-basic, respectively. The electrochemically-generated radical cation of the title compound is long-lived as characterized by electron paramagnetic resonance, whereas the radical anion is unstable in solution. The title compound reveals electrical properties of an insulator. On expanding its molecular scaffold towards partially fluorinated [n]phenylenes (n≥2), the properties presumably can be transformed into those of semiconductors. In this context, the title compound is suggested as a prototype scaffold for ambipolar materials for organic electronics and spintronics.

N-Coordinated tellurenium(II) and telluronium(IV) cations: synthesis, structure and hydrolysis.

A set of N-coordinated tellurium(II) compounds containing either C,N-chelating ligands CNR (where CN = 2-(RNCH)C6H4, R = tBu or Dipp; Dipp = 2,6-iPr2C6H3) or N,C,N pincer ligands NCNR (where NCN = 2,6-(RNCH)2C6H4, R = tBu or Dipp) were synthesized. In the case of C,N-chelated compounds, the reaction of CNDippLi with Te(dtc)2 (where dtc = Et2NCS2) in a 1 : 1 molar ratio smoothly provided the carbamate CNDippTe(dtc) which upon treatment with 2 eq. of HCl provided the chloride CNDippTeCl. In contrast, the analogous conversion of NCNRLi with Te(dtc)2 surprisingly furnished ionic bromides [NCNRTe]Br as a result of the exchange of dtc by Br coming from nBuBr present in the reaction mixture. Furthermore, the reaction of CNDippTeCl or [NCNRTe]Br with silver salts AgX (X = OTf or SbF6) provided the expected tellurenium cations [CNDippTe]SbF6 and [NCNRTe]X. To further increase the Lewis acidity of the central atom, the oxidation of selected compounds with 1 eq. of SO2Cl2 was examined yielding stable compounds [CNtBuTeCl2]X and [NCNtBuTeCl2]X. The oxidation of the Dipp substituted compounds proved to be more challenging and an excess of SO2Cl2 was necessary to obtain the oxidized products [CNDippTeCl2]SbF6 and [NCNDippTeCl2]SbF6, which could solely be characterized in solution. Compounds [CNtBuTeCl2]OTf and [NCNtBuTeCl2]OTf were shown to undergo a controlled hydrolysis to the corresponding telluroxanes. All compounds were studied by multinuclear NMR spectroscopy in solution and for selected compounds solid state 125Te NMR spectroscopy and single-crystal X-ray diffraction analysis were performed. The Lewis acidity of the studied cations was examined by the Gutmann-Beckett method using Et3PO as the probing agent. The Te-N chalcogen bonding situation of selected compounds has also been examined computationally by a set of real-space bonding indicators.

Aryldimethylelement cations of the heavier group 14 elements. An essentially three-coordinate plumbylium ion.

The kinetically stabilized group 14 cations [RindEMe2][B(C6F5)4] (E = Si, Sn, Pb) were prepared and fully characterized (Rind = dispiro[fluorene-9,3'-(1',1',7',7'-tetramethyl-s-hydrindacen-4'-yl)-5',9''-fluorene). The deshielded heteronuclear NMR chemical shifts (δ(29Si) = 160.4, δ(119Sn) = 619.9, δ(207Pb) = 1549.5) are indicative of the low coordination numbers.

An investigation into the Brønsted acidity of the perfluorinated alkoxy silanes {(F3C)3CO}3SiH and {(F6C5)3CO}2Si(Cl)H.

The perfluorinated alkoxy silanes {(F3C)3CO}3SiH (1) and {(F5C6)3CO}2Si(Cl)H (2) were prepared and fully characterized. Despite the high calculated Brønsted acidities, all attempts to deprotonate 1 and 2 to give the conjugate silanide ions failed due to the exceptionally short and strong Si-H bonds. In the solid state, the Si-H units are not involved in any intermolecular interactions, but instead the crystal packing consists of exceptionally short and strong F⋯F interactions. The cohesive energies are entirely comprised of London dispersion interactions, similarly as in the crystal structures of noble gases.

In silico capture and activation of methane with light atom molecules.

Methane (CH4) can be captured in silico with a light atom molecule containing only C, H, Si, O, and B atoms, respectively. A tripodal peri-substituted ligand system was employed, namely, [(5-Ph2B-xan-4-)3Si]H (1, xan = xanthene), which after hydride abstraction (1+) carries four Lewis acidic sites within the cationic cage structure. In a previous study, this system was shown to be able to capture noble gas atoms He-Kr (Mebs & Beckmann 2022). In the corresponding methane complex, 1+CH4, a polarized Si+⋯CH4 contact of 2.289 Å as well as series of (H3)CH⋯O/CPh hydrogen bonds enforce spatial CH4 fixation (the molecule obeys C3-symmetry) and slight activation. A trigonal-pyramidal Si-CHeq3-Hax local geometry is thereby approached with Hax-C-Heq angles decreased to 103.7°. All attempts to replace the Lews acidic -BPh2 fragments in 1 with basic -PR2 (R = Ph, tBu) fragments indeed increased intra-molecular hydrogen bonding between host molecule and CH4, and thus caused stronger activation of the latter, however ultimately resulted in the formation of energetically favorable quenched structures with short P-Si contacts, making CH4 binding hard to achieve. The electronic situation of two hypothetic methane complexes, 1+CH4 and [(5-tBu2P-xan-4-)3SiCH4]+ (2+CH4), was determined by a set of calculated real-space bonding indicators (RSBIs) including the Atoms-In-Molecules (AIM), non-covalent interactions index (NCI), and electron localizability indicator (ELI-D) methods, highlighting crucial differences in the level of activation. The proposed ligand systems serve as blueprints for a more general structural design with adjustable trigonal ligand systems in which central atom, spacer fragment, and functional peri-partner can be varied to facilitate different chemical tasks.

Kinetically Stabilized Diarylpnictogenium Ions.

The newly prepared and fully characterized stibenium and bismuthenium ions [Rind MesE]+ (E=Sb, Bi; Rind =dispiro[fluorene-9,3'-(1',1',7',7'-tetramethyl-s-hydrindacen-4'-yl)-5',9''-fluorene) were rigorously compared to the previously communicated phosphenium and arsenium ions (E=P, As) as well as the bis(m-terphenyl) pnictogenium ions [(2,6-Mes2 C6 H3 )2 E]+ (E=Sb, Bi). It is demonstrated that the choice of the aryl substituents dramatically effects the molecular structures (e. g. the primary E-C bond lengths) and the electronic structures (e. g. the energy of the LUMOs).

Tuning Molecular Electron Affinities against Atomic Electronegativities by Spatial Expansion of a π-System.

2,1,3-Benzochalcogenadiazoles C6 R4 N2 E (E/R; E=S, Se, Te; R=H, F, Cl, Br, I) and C6 H2 R2 N2 E (E/R'; E=S, Se, Te; R=Br, I) are 10π-electron hetarenes. By CV/EPR measurements, DFT calculations, and QTAIM and ELI-D analyses, it is shown that their molecular electron affinities (EAs) increase with decreasing Allen electronegativities and electron affinities of the E and non-hydrogen R (except Cl) atoms. DFT calculations for E/R+e⋅- →[E/R]⋅- electron capture reveal negative ΔG values numerically increasing with increasing atomic numbers of the E and R atoms; positive ΔS has a minor influence. It is suggested that the EA increase is caused by more effective charge/spin delocalization in the radical anions of heavier derivatives due to contributions from diffuse (a real-space expanded) p-AOs of the heavier E and R atoms; and that this counterintuitive effect might be of the general character.

Synthesis and Single-Electron Oxidation of Bulky Bis(m-terphenyl)chalcogenides: The Quest for Kinetically Stabilized Radical Cations.

Sterically encumbered bis(m-terphenyl)chalcogenides, (2,6-Mes2 C6 H3 )2 E (E=S, Se, Te) were obtained by the reaction of the chalcogen tetrafluorides, EF4 , with three equivalents of m-terphenyl lithium, 2,6-Mes2 C6 H3 Li. The single-electron oxidation of (2,6-Mes2 C6 H3 )2 Te using XeF2 /K[B(C6 F5 )4 ] afforded the radical cation [(2,6-Mes2 C6 H3 )2 Te][B(C6 F5 )4 ] that was isolated and fully characterized. The electrochemical oxidation of the lighter homologs (2,6-Mes2 C6 H3 )2 E (E=S, Se) was irreversible and impaired by rapid decomposition.

In silico capture of noble gas atoms with a light atom molecule.

Noble gas atoms (Ng = He, Ne, Ar, and Kr) can be captured in silico with a light atom molecule containing only C, H, Si, O, and B atoms. Extensive density functional theory (DFT) calculations on series of peri-substituted scaffolds indicate that confined spaces (voids) capable to energy efficiently encapsulate and bind Ng atoms are accessible by design of a tripodal peri-substituted ligand, namely, [(5-Ph2B-xan-4-)3Si]H (xan = xanthene) comprising (after hydride abstraction) four Lewis acidic sites within the cationic structure [(5-Ph2B-xan-4-)3Si]+. The host (ligand system) thereby provides an adoptive environment for the guest (Ng atom) to accommodate for its particular size. Whereas considerable chemical interactions are detectable between the ligand system and the heavier Ng atoms Kr and Ar in the host guest complex [(5-Ph2B-xan-4-)3Si·Ng]+, the lighter Ng atoms Ne and He are rather tolerated by the ligand system instead of being chemically bound to it, nicely highlighting the gradual onset of (weak) chemical bonding along the series He to Kr. A variety of real-space bonding indicators (RSBIs) derived from the calculated electron and pair densities provides valuable insight to the situation of an "isolated atom in a molecule" in case of He, uncovering its size and shape, whereas minute charge rearrangements caused by polarization of the outer electron shell of the larger Ng atoms results in formation of polarized interactions for Ar and Kr with non-negligible covalent bond contributions for Kr. The present study shows that noble gas atoms can be trapped by small light-atom molecules without the forceful conditions necessary using cage structures such as fullerenes, boranes and related compounds or by using super-electrophilic sites like [B12(CN)11]- if the chelating effect of several Lewis acidic sites within one molecule is employed.

Intelligence IS Cognitive Flexibility: Why Multilevel Models of Within-Individual Processes Are Needed to Realise This.

Despite substantial evidence for the link between an individual's intelligence and successful life outcomes, questions about what defines intelligence have remained the focus of heated dispute. The most common approach to understanding intelligence has been to investigate what performance on tests of intellect is and is not associated with. This psychometric approach, based on correlations and factor analysis is deficient. In this review, we aim to substantiate why classic psychometrics which focus on between-person accounts will necessarily provide a limited account of intelligence until theoretical considerations of within-person accounts are incorporated. First, we consider the impact of entrenched psychometric presumptions that support the status quo and impede alternative views. Second, we review the importance of process-theories, which are critical for any serious attempt to build a within-person account of intelligence. Third, features of dynamic tasks are reviewed, and we outline how static tasks can be modified to target within-person processes. Finally, we explain how multilevel models are conceptually and psychometrically well-suited to building and testing within-individual notions of intelligence, which at its core, we argue is cognitive flexibility. We conclude by describing an application of these ideas in the context of microworlds as a case study.

In silico activation of dinitrogen with a light atom molecule.

The NN triple bond can be cleaved in silico with a light atom molecule containing only the earth abundant elements C, H, Si, and P. Extensive density functional theory (DFT) computations on various classes of peri-substituted scaffolds containing Lewis acidic and basic sites in the framework of frustrated Lewis pairs (FLP) indicate that the presence of two silyl cations and two P atoms in a flexible but not too flexible arrangement is essential for energy efficient N2-activation. The non-bonding lone-pair electrons of the P atoms thereby serve as donors towards N2, whereas the lone-pairs of N2 donate into the silyl cations. Newly formed lone-pair basins in the N2-adducts balance surplus charge. Thereby, the N-N bond distance is increased by astonishing 0.3 Å, from 1.1 Å in N2 gas to 1.4 Å in the adduct, which makes this bond prone to subsequent addition of hydride ions and protonation, forming two secondary amine sites in the process and eventually breaking the NN triple bond. Potential formation of dead-end states, in which the dications ("active states") aversively form a Lewis acid (LA)-Lewis base (LB) bond, or in which the LA and LB sites are too far away from each other to be able to capture N2, are problematic but might be circumvented by proper choice of spacer molecules, such as acenaphthalene or biphenylene, and the ligands attached to the LA and LB atoms, such as phenyl or mesityl, and by purging the reaction solutions with gaseous N2 in the initial reaction steps. Charge redistributions via N2-activation and splitting were monitored by a variety of real-space bonding indicators (RSBIs) derived from the calculated electron and electron pair densities, which provided valuable insight into the bonding situation within the different reaction steps.

Heavier bis(m-terphenyl)element phosphaethynolates of group 13.

The synthesis and reactivity of the heavier group 13 phosphaketene complexes (2,6-Mes2C6H3)2EPCO (1, E = Ga; 2, E = In) were reported. The reaction of 1 and 2 with 1,2,3,4-tetramethylimidazolin-2-ylidene, IMe4, gave rise to the formation of (2,6-Mes2C6H3)2EP(O)C(IMe4) (3, E = Ga; 4 E = In; Mes = mesityl). Subsequent addition of elemental tellurium proceeded via insertion into the E-P bond and provided (2,6-Mes2C6H3)2ETeP(O)C(IMe4) (5, E = Ga; 6, E = In) comprising five-membered ETePCO-heterocycles. Compounds 1-6 were fully characterized by X-ray crystallography and heteronuclear NMR spectroscopy. The electronic structures of 1-6 were studied by DFT calculations and analyses of a complementary set of real-space bonding indicators (AIM, ELI-D, NCI) derived from the electron and pair densities, with focus on the bond characteristics of the PCO fragment.

Nickel and Palladium Complexes of a PP(O)P Pincer Ligand Based upon a peri-Substituted Acenaphthyl Scaffold and a Secondary Phosphine Oxide.

A PP(O)P pincer ligand based upon a peri-substituted acenaphthyl (Ace) scaffold and a secondary phosphine oxide, (5-Ph2P-Ace-6-)2P(O)H, was prepared and fully characterized including a neutron diffraction study. The reaction with [Ni(H2O)6]Cl2 and PdCl2 produced ionic metal(II) complexes [κ3-P,P',P''((5-Ph2P-Ace-6-)2P(OH))MCl]Cl, which upon addition of Et3N gave rise to zwitterionic metal(II) complexes κ3-P,P',P''((5-Ph2P-Ace-6-)2P(O))MCl (M = Ni, Pd). The reaction with Ni(COD)2 (COD = cyclooctadiene) provided the η3-cyclooctenyl Ni(II) complex κ3-P,P',P''((5-Ph2P-Ace-6-)2P(O))Ni(η3-C8H13). A detailed complementary bonding analysis of the P-H, P-O, and P-M interactions was carried out (M = Ni, Pd).

Donor Acceptor Complexes between the Chalcogen Fluorides SF2 , SeF2 , SeF4 and TeF4 and an N-Heterocyclic Carbene.

The majority of binary chalcogen fluorides are fiercely reactive and extremely difficult to handle. Here, we show that access to crystalline donor-acceptor complexes between chalcogen difluorides (sulfur, selenium) and tetrafluorides (selenium, tellurium) with the N-heterocyclic carbene (NHC) 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) is possible conveniently and safely without the need to generate the highly unstable EF2 (E=S, Se) or the very toxic and corrosive SeF4 .

Sophisticated Statistics Cannot Compensate for Method Effects If Quantifiable Structure Is Compromised.

Researchers rely on psychometric principles when trying to gain understanding of unobservable psychological phenomena disconfounded from the methods used. Psychometric models provide us with tools to support this endeavour, but they are agnostic to the meaning researchers intend to attribute to the data. We define method effects as resulting from actions which weaken the psychometric structure of measurement, and argue that solution to this confounding will ultimately rest on testing whether data collected fit a psychometric model based on a substantive theory, rather than a search for a model that best fits the data. We highlight the importance of taking the notions of fundamental measurement seriously by reviewing distinctions between the Rasch measurement model and more generalised 2PL and 3PL IRT models. We then present two lines of research that highlight considerations of making method effects explicit in experimental designs. First, we contrast the use of experimental manipulations to study measurement reactivity during the assessment of metacognitive processes with factor-analytic research of the same. The former suggests differential performance-facilitating and -inhibiting reactivity as a function of other individual differences, whereas factor-analytic research suggests a ubiquitous monotonically predictive confidence factor. Second, we evaluate differential effects of context and source on within-individual variability indices of personality derived from multiple observations, highlighting again the importance of a structured and theoretically grounded observational framework. We conclude by arguing that substantive variables can act as method effects and should be considered at the time of design rather than after the fact, and without compromising measurement ideals.

Coordination-Induced Band Gap Reduction in a Metal-Organic Framework.

Herein, we report on the synthesis of a microporous, three-dimensional phosphonate metal-organic framework (MOF) with the composition Cu3 (H5 -MTPPA)2 ⋅ 2 NMP (H8 -MTPPA=methane tetra-p-phenylphosphonic acid and NMP=N-methyl-2-pyrrolidone). This MOF, termed TUB1, has a unique one-dimensional inorganic building unit composed of square planar and distorted trigonal bipyramidal copper atoms. It possesses a (calculated) BET surface area of 766.2 m2 /g after removal of the solvents from the voids. The Tauc plot for TUB1 yields indirect and direct band gaps of 2.4 eV and 2.7 eV, respectively. DFT calculations reveal the existence of two spin-dependent gaps of 2.60 eV and 0.48 eV for the alpha and beta spins, respectively, with the lowest unoccupied crystal orbital for both gaps predominantly residing on the square planar copper atoms. The projected density of states suggests that the presence of the square planar copper atoms reduces the overall band gap of TUB1, as the beta-gap for the trigonal bipyramidal copper atoms is 3.72 eV.