The Reaction of a Nitro-Capped Cobalt(III) Cage Complex With Base: the Crystal Structure of a Contracted Cage Complex, and the Mechanism of Its Formation

The synthesis, properties and crystal structure of the cage complex (1-hydroxy-8-methyl-3,6,10,13,15,18-hexaazabicyclo[6.6.5]nonadecane)cobalt(III) chloride hydrate ([Co(Me,OH-absar)] C13.H2O) are reported. The mechanism of the formation of this contracted cavity cage from a nitro-capped hexaazabicycloicosane type cage has been investigated. Treatment of (1-methyl-8-nitro-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane)cobalt(III) chloride ([Co(Me,NO2-sar)] 3+) with excess base in aqueous solution leads initially to rapid (t1/2 < 1 ms) and reversible deprotonation of one coordinated secondary amine. This species undergoes a retro-Mannich type reaction and imine hydrolysis (t1/2 almost-equal-to 90 s). Quenching the reaction with acid gives rise to a pair of isomeric intermediate species which have been isolated and characterized. They have a pendant arm macrocyclic structure, resulting from the loss of a methylene unit from one of the arms of the cap. Heating either isomer in aqueous solution gives the new cage compound with the contracted cap. It is postulated that this occurs through a Nef reaction, resulting in the formation of a ketone which then condenses with the coordinated primary amine. A comparison with the corresponding bicycloicosane analogue indicates a reduced chromophoric cavity size for the contracted cage. The reduction potential of the cobalt(III)/cobalt(II) couple is 170 mV more negative for the smaller cage, and, in the electronic spectrum of the cobalt(III) complex, the d-d transitions are both shifted to higher energy, corresponding to a stronger ligand field

An expanded cavity hexaamine cage for copper(II)

The crystal structure of the bicyclic hexaamine complex [Cu(fac-Me-5-tricosane-N-6)](ClO4)(2) center dot H2O (fac-Me-5-tricosane-N-6 = facial-1,5,9,13,20-pentamethyl-3,7,11,15,18,22-hexaazabicyclo[7.7.7] tricosane) at 100 K defines an apparently tetragonally compressed octahedral geometry, which is attributed to a combination of dynamic interconversion and static disorder between two tetragonally elongated structures sharing a common short axis. This structure is fluxional at 60 K and above as shown by EPR spectroscopy. Aqueous cyclic voltammetry reveals that a remarkably stable Cu-I form of the complex is stabilised by the encapsulating nature of the expanded cage ligand

Why Women Own Less, And Why It Matters More in Rural China’s Urban Transformation

As the amount of wealth in China’s economy grows, so too does the size of the gender asset gap. Nowhere is this gap more extreme, or its consequences for women’s future wealth, subjectivity, and agency more serious, than in peri-urban sites where the conversion of farmland for development has sent property values skyrocketing. This article explores how the gender asset gap is being reproduced in the course of rural China’s urban transformation. It queries the plausibility of the most common explanations for this gap, and suggests that Charles Tilly’s theory of categorical sources of “durable inequality” offers a useful corrective to those explanations. Drawing on data collected from interviewees and survey respondents in Zhejiang, Fujian, Hunan, and Yunnan provinces between 2004 and 2012 and from secondary sources, the paper illustrates how, when villagers are compensated for the expropriation of their land and demolition of their agricultural and business activities and housing, Village Committees, patrilineal households, and local government authorities utilise gender categories to resolve distributional problems and differentially compensate men. Women become less likely than men to be acknowledged as, and have the capacity to fully act as, the owners, managers, and users of the assets whose value increases as a result of urbanisation

Tamara Jacka, Rural Women in Urban China: Gender, Migration and Social Change.

China’s "urban revolution" has become the focus of a large body of literature in recent years. But while much of the new urbanisation literature builds on earlier research into the roles played by rural-urban migration in propelling urban population growth, challenging urban governance institutions and practices, and diversifying urban cultures, there has been relatively little attention given to the gender analysis agenda that undergirded and enriched some of the best studies of rural-urban ..

Tamara Jacka, Rural Women in Urban China: Gender, Migration and Social Change.

Ces dernières années la « révolution urbaine » chinoise est devenue l’objet d’une abondante littérature. Cependant, l’essentiel de ces nouvelles recherches s’inspire d’études plus anciennes concernant le rôle joué par la migration campagne-ville dans l’explosion des populations citadines, le défi qu’elle lance aux institutions et aux pratiques de gouvernance, et la diversification des cultures urbaines qu’elle entraîne. Peu d’attention a comparativement été consacrée aux revendications de gen..

Pourquoi les femmes possèdent-elles moins ? Le cas des campagnes en voie d’urbanisation

L’augmentation de la richesse en Chine, résultat de la forte croissance de l’économie ces dernières années, s’est accompagnée d’un creusement des inégalités entre les sexes dans la possession d’actifs. Ce fossé n’est nulle part plus marqué – et ses conséquences sur l’avenir des femmes plus préoccupantes – que dans les zones périurbaines où la conversion des terres agricoles en terrains constructibles a fait exploser les prix de l’immobilier. Cet article examine comment ces inégalités se perpétuent dans le processus d’urbanisation des campagnes chinoises. Il remet en question les raisons les plus couramment acceptées pour expliquer ces inégalités et suggère que la théorie de Tilly sur les causes catégorielles des « inégalités durables » offre un correctif utile à ces explications. En s’appuyant sur des données d’enquête et d’entretiens menés entre 2004 et 2012 dans le Zhejiang, le Fujian, le Hunan et le Yunnan, ainsi que sur des sources de seconde main, cet article montre comment, lorsque les paysans sont expropriés de leurs terres et que leur outil de travail, leurs cultures et leur logement sont détruits, les familles, les comités de village et les autorités gouvernementales locales se fondent sur les catégories de genre pour fixer le montant des indemnités compensatoires et dédommagent les hommes de manière plus avantageuse que les femmes. Il devient alors plus difficile pour ces dernières de faire valoir leurs droits à la propriété ou à diriger des entreprises au moment même où la valeur de ces actifs augmente du fait de l’urbanisation

Computational Insights into the Isomerism of Hexacoordinate Metal–Sarcophagine Complexes: The Relationship between Structure and Stability

The hexacoordinate complexes that the macrobicyclic ligands {(NH3)2sar}2+ and {(NMe3)2sar}2+ (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) form with transition metals such as CoIII, CoII and CuII can adopt several isomeric structures. In this article, we have firstly employed DFT methods to compute the relative stability of their Δ-ob3, Δ-ob2lel, Δ-lel2ob and Δ-lel3 isomers, as well as the activation barriers for their interconversion. In agreement with the experimental data, the results show that, in general, the different isomers of the CoIII and CoII complexes present similar free energies, whereas the CuII complexes show a strong tendency towards the lel3 form. In addition, the interplay between the structure and stability of these species has been studied by combining shape maps with a distortion/interaction energy analysis. In contrast to the geometries close to the ideal octahedron that all the studied Co complexes present, the lel3 structures of [Cu{(NH3)2sar}]4+ and [Cu{(NMe3)2sar}]4+ are better described as trigonal prisms. In such structures the ligand adopts a conformation significantly more stable than in the other isomers, and this drives the formation of lel3-[Cu{(NH3)2sar}]4+ and lel3-[Cu{(NMe3)2sar}]4+. Overall, the results show a clear relationship between the stability of a given isomer and its degree of distortion with respect to the ideal octahedron (or trigonal prism), with the latter being ultimately dependent on the transition metal and its radius