1,564 research outputs found
sj-pdf-1-mrj-10.1177_00222437231169711 - Supplemental material for Words Meet Photos: When and Why Photos Increase Review Helpfulness
No full textSupplemental material, sj-pdf-1-mrj-10.1177_00222437231169711 for Words Meet Photos: When and Why Photos Increase Review Helpfulness by Gizem Ceylan, Kristin Diehl and Davide Proserpio in Journal of Marketing Research</p
. Stabilization of trivalent nickel through 1:2 coordination by cyclic terdentate ligands CH2CH2NH(CH2)2NH(CH2)2X (X = NH, O, or S)
No full textThe octahedral 6-coordinated complexes [Ni(L)2]2+ (L = 1-oxa-4,7-diazacyclononane; L1 = 1-thia-4,7-diazacyclononane) (donor set: N4O2 and N4S2, resp.) undergo a reversible 1-electron oxidn. in MeCN and DMSO solns. to give authentic Ni(III) species. These Ni(III) complexes present a distorted stereochem. arrangement, with the O and S heteroatoms occupying the axial sites of an elongated octahedron, and they persist in soln. for hours. Comparison with the corresponding complexes of 1,4,7-triazacyclonanane (L2) (donor set: N6) indicates that the relative stability of the trivalent species, expressed by the value of E1/2(Ni(III)-Ni(II)), decreases along the series: L2 > L1 > L, the trend reflecting the decrease in the strength of the Ni-X interactions (X = N, S, or O). The corresponding Ni(III) complexes of the open-chain analogs of the macrocycles L3 or L1 form at comparable potentials, but persist in soln. only in the time-scale of the voltammetry expt., thus demonstrating the existence of a purely kinetic macrocyclic effect in the stabilization of high oxidn. states of metals
Experimental electron density in a transition metal dimer: Metal-metal and metal-ligand bonds
No full textThe accurate experimental electron density distribution of Co2(CO)6(AsPh3)2 has been determined through X-ray diffraction at T = 123 K. Metal-metal and metal-ligand bonds have been investigated by means of deformation densities and the quantum theory of atoms in molecules. The 'expected' lack of charge accumulation in the deformation density map is 'contradicted' by the presence of a bond critical point and a bond path line linking the two Cobalt atoms, in agreement with theoretical predictions on similar compounds. A careful analysis of the properties of ρ(r) at the bond critical points and of the Laplacian distribution along the bond paths has allowed the full characterization of all bonds in the title compound and, in particular, to discard the apparently straightforward classification of Co- Co as a closed-shell interaction. The radial shape of the atomic Laplacian makes (covalent or polar) shared interactions similar to donor-acceptor ones when at least one 'heavy atom' is concerned. Thus, even if it is possible to recognize the shared character of Co-Co and As-C bonds by comparison with the donor-acceptor C-Co and As-Co interactions, this distinction is grounded on subtleties which could possibly not suffice without some a priori chemical insight
Experimental electron density studies for investigating the metal π- Ligand bond: The case of bis(1,5-cyclooctadiene)nickel
No full textThe accurate experimental electron density of crystalline bis(5- cyclooctadiene)nickel, Ni(COD)2, has been determined by X-ray diffraction (T = 125 K, 17 051 reflections measured for 2θ ≤ 96°) and it has been interpreted in terms of quantum theory of atoms in molecules (QTAM). The data were measured with a CCD area detector, whose performances were tested. This experimental electron density study of a π-ligand η2-coordinated to a metal atom is intended to test the Dewar-Chatt-Duncanson (DCD) bonding formalism providing further information about the π-complex vs metallacycle dichotomy. QTAM analysis, within the NiC2 triangle, shows a ring structure with a bond critical point between the two C(sp2), two bond critical points between Ni and each carbon, and one ring critical point in its center. Topology speaks for a π-complex with a concave ring structure and the overall bonding picture is in agreement with the DCD model: σ-donation and π-back-bonding are recognized in the Ni-C bond paths, which are inwardly curved (σ-donation) but well separated (π-back-donation)
Site preference of ligand and metal substitution in trigonal-bipyramidal metal carbonyl clusters
No full textGimarc's topological charge stabilization rule (TCS), for addressing site preference, has been extended to the realm of metal carbonyl clusters using Allen's energy indexes (Els) instead of charges. EIs have been computed within the extended Hückel (EH) approximation and, in order to assess an internal electronegativity scale for transition metals and to allow comparisons across the periodic table, a homogeneous set of EH parameters has been determined. EIs have been shown to behave similarly to charges on "clusters" with a rigid ligand stereochemistry like carboranes but, when one deals with metal carbonyl clusters and their intriguing ligand mobility, EIs are definitely superior to charges. EIs do address both "skeletal" and "ligand" site preferences according to the following rules of thumb: (i) more electronegative metal atoms occupy higher El sites of the uniform reference frame (URF) (i.e. the one with the lower local electronegativity) and (ii) (nucleophilic) ligand substitution preferentially occurs on the lowest energy index site of the URF (i.e. the one with the largest electrophilic character). Previous attempts to rationalize site preference in metal clusters were mainly concerned with the relative strengths of metal-metal and metal-ligand bonds and substantially disregarded electronegativity differences between different metal atoms. In contrast, we have shown that the latter are important whenever the actual URF allows for different EIs on different metal sites. In particular, differences in electronegativity have been shown to be important for M5L15and M5L12but not for M5L12bipyramidal metal carbonyl clusters. © 1997 American Chemical Society
Using long bis(4-pyridyl)ligands designed for the self-assembly of coordination frameworks and architectures
No full textNowcasting Gentrification Using Airbnb Data
No full textThere is a rumbling debate over the impact of gentrification: presumed gentrifiers have been the target of protests and attacks in some cities, while they have been welcome as generators of new jobs and taxes in others. Census data fails to measure neighborhood change in real-Time since it is usually updated every ten years. This work shows that Airbnb data can be used to quantify and track neighborhood changes. Specifically, we consider both structured data (e.g., number of listings, number of reviews, listing information) and unstructured data (e.g., user-generated reviews processed with natural language processing and machine learning algorithms) for three major cities, New York City (US), Los Angeles (US), and Greater London (UK). We find that Airbnb data (especially its unstructured part) appears to nowcast neighborhood gentrification, measured as changes in housing affordability and demographics. Overall, our results suggest that user-generated data from online platforms can be used to create socioeconomic indices to complement traditional measures that are less granular, not in real-Time, and more costly to obtain. </p
An unusual three-dimensional coordination network formed by parallel polycatenation of two-fold interpenetrated (6,3) layers based on novel three-connecting ligand
No full textUsing Traditional Text Analysis and Large Language Models in Service Failure and Recovery
No full textService failure and recovery (SFR) typically involves one or more people (or machines) talking or writing to each other in a goal-directed conversation. While SFR represents a prime context to understand how language reflects and shapes the service experience, this subfield has only begun to apply text analysis methods and language theories to this context. This tutorial offers a methodological guide for traditional text analysis methods and large language models and suggests some future research paths in SFR. We also provide user-friendly workflow repositories, in Python and KNIME Analytics, that researchers with (and without) coding experience can use. In doing so, we hope to encourage the next wave of text analysis in SFR researc
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