rac-(OC-6-33)-bis­[2-(N-Benzyl­methyl­imino­meth­yl-κN)-1H-imidazol-1-ido-κN 1]bis(ethyl­amido)­titanium(IV)

The title compound, [[Ti(C2H10N)2(C11H10N3)2] or Ti(C11H10N3)2(NEt2)2], was prepared by direct reaction of 2-(N-phenyl­methyl­imino­meth­yl)-1H-imidazole and [Ti(NEt2)4]. The TiIV atom is in a pseudo-octa­hedral coordination environ­ment with the imidazolido-group N-atoms occupying apical positions and amido- and imino-N-atoms cis-located in the equatorial plane. The presence of two bidentate chelating ligands determines the chirality of the TiIV atom. The crystallographically independent unit, except for its phenyl rings, adopts nearly pseudo-C 2 symmetry (rotation around a twofold axis passing through the Ti atom and the centre of the imino-N⋯imino-N segment). The Ti—Namido, Ti—Nimidazolido, and Ti—Nimino bond lengths essentially differ, increasing by approximately 0.2 Å in the series. All ligating N atoms are in a nearly planar environment, which is indicative of additional pπ–dπ donations towards the metal atom. The two diaza­metallacyclic units are planar within 0.03 and 0.05 Å

Migration's contribution to the urban transition: Direct census estimates from Africa and Asia

Background: The components of urbanisation are important to understand, since urbanisation is closely related to development. Internal migration was key in historical urban transitions, while in contemporary transitions the balance of births and deaths has been the main driver of urbanisation. Reclassification of rural areas and international migration also contribute to urbanisation. Objective: Unlike previous work based on indirectly measured net migration estimates, we directly estimate in- and out-migration rates between rural and urban areas across Africa and Asia by age and sex, and evaluate the contribution of the balance of these flows to urbanisation. Methods: We use 67 census samples from IPUMS International for 28 countries in Africa and Asia between 1970 and 2014 to estimate in- and out- migration between rural and urban areas, based on available questions of residence. We then model age- and sex-specific migration rates using Poisson regression and estimate net migration through marginal effects. Results: Results confirm that, in both continents, urbanisation is not generated by rural-to-urban migration but by the urban population itself, be it through natural growth or through expansion to peripheral areas. In Asia, urbanisation reflects internal migration trends and reclassification decisions to a greater extent than in Africa, where natural growth is the key contributor. Conclusions: In Asia, urbanisation reflects internal migration trends and reclassification decisions to a greater extent than in Africa where natural growth is the key contributor. Contribution: By using direct estimates, we ascertain the role of inter-regional rural-urban migration in urbanisation. We find that a positive effect of inter-regional migration is counter-balanced by a negative effect of intra-regional migration (combined with reclassification and international migration)

Trichlorido{2-[2-(η5-cyclo­penta­dien­yl)-2-methyl­prop­yl]-1-trimethyl­silyl-1H-imidazole-κN 3}titanium(IV) tetra­hydro­furan hemisolvate

The title compound, [Ti(C15H23N2Si)Cl3]·0.5C4H8O, has been prepared from {2-[2-(η5-cyclo­penta­dien­yl)-2-methyl­prop­yl]-1H-imidazolyl-κN 1}bis­(N,N-diethyl­amido-κN)titanium(IV), (C12H14N2)Ti(NEt2)2, by reaction with excess of Me3SiCl in tetra­hydro­furan (THF) at 353 K. The crystal structure contains THF as adduct solvent, disordered around a center of inversion. The presence of THF and the adduct ratio has been independently supported by 1H NMR spectroscopy. The coordination polyhedron of the Ti atom is distorted square-pyramidal, assuming the cyclo­penta­dienyl (Cp) ring occupies one coordination site. The Ti, Si and CH2 group C atoms only deviate slightly from the imidazole ring plane [by 0.021 (4), 0.133 (4) and 0.094 (4) Å, respectively]. Comparison of the principal geometric parameters with those of the few known structurally characterized analogues reveal small differences in bond lengths and angles at the Ti atom. The title complex is only stable in THF-d 8 in the presence of excess Me3SiCl, otherwise it exists in an equilibrium with equimolar amounts of dichlorido{2-[2-(η5-cyclo­penta­dien­yl)-2-methyl­prop­yl]-1H-imidazolyl-κN 3}titanium(IV) and chloro­trimethyl­silane

2-{(E)-N-[2-(1H-Inden-3-yl)eth­yl]imino­meth­yl}-1H-imidazole

The asymmetric unit of the title compound, C15H15N3, contains two crystallographically independent mol­ecules with very similar geometries. The imidazole and indenyl planes are approximately orthogonal, making dihedral angles of 88.21 (9) and 83.08 (9)%deg; in the two independent molecules. In the crystal, the imidazole units are linked by N—H⋯N hydrogen bonds into chains parallel to the 101) plane stretched in the diagonal direction [translation vector (,1,0); C(4) motif]. Within a chain, there are two types of symmetrically non-equivalent alternating H-bonds which slightly differ in their parameters

Demographic change and increasing late singlehood in East Asia, 2010-2050

Background: Marriage is a central institution for social reproduction in East Asia. Until the 1970s and 1980s, marriage across much of East Asia was early and universal. In recent decades, though, this pattern has begun shifting to one of later and less marriage. Objective: We explore the long-term implications for universal marriage patterns of future demographic change in marriage markets in the context of prevailing marriage norms by projecting trends in late singlehood (ages 45 to 49) in four East Asian societies (China, South Korea, Taiwan, and Japan). Methods: We estimate forces of attraction to characterize marriage matching norms by age and education across these different societies by drawing on large-scale population data. Next, we develop counterfactual scenarios in which we apply contemporary norms to future population structures in these societies, as well as scenarios based on more gender-symmetrical matching norms to examine how populations who have never been married by ages 45 to 49 would evolve. Results: Our projections indicate that in the coming decades there will be a substantial increase in late singlehood across all these societies relative to their 2010 levels. These increases in singlehood are driven by forthcoming demographic changes in the marriage market that intensify the effects of prevailing matching norms. These increases are notable in Taiwan and South Korea, where recent data indicate generalized weak propensities to marry in current norms. While a shift toward greater gender symmetry in matching norms would reverse gender gaps between men and women in nonmarriage, it would have little impact on the overall projected proportions of singles by ages 45 to 49. Conclusions: If prevailing norms in each of these contexts continue, the universality of marriage will be substantially eroded in the coming decades, even if norms become more gender symmetrical. The extent to which nonmarital cohabitation and childbearing emerge in the future will determine how marriage will influence fertility trends, population growth, aging, and social reproduction. Contribution: For the first time, we project the implications for universal marriage of recent shifts in marriage norms and demographic change in East Asian countries

(Diethyl ether){1-[2-(1-methyl-1H-imidazol-2-yl-κN 3)-1,1-diphenyl­ethyl]-(1,2,3,3a,7a-η)-inden­yl}lithium(I)

In the title compound, [Li(C27H23N2)(C4H10O)], the Li atom possesses a nearly planar trigonal coordination environment (assuming the cyclo­penta­dienyl ring of the indenyl group occupies one coordination place). The diethyl ether ligand adopts a nearly planar W-type conformation

Trichlorido(tetra­hydro­furan){(1,2,3,3a,7a-η)-1-[2-(1-trimethyl­silyl-1H-imidazol-2-yl-κN 3)-1-methyl­prop­yl]inden­yl}zirconium(IV)

The title compound, [ZrCl3(C19H25N2Si)(C4H8O)], was prepared from bis­(N,N-dimethyl­amido-κN)(2-{2-[(1,2,3,3a,7a-η)-inden­yl]-2-methyl­prop­yl}-1H-imidazolido-κN 1)zirconium(IV) [(C16H16N2)Zr(NMe2)] by reaction with excess Me3SiCl in tetra­hydro­furan (THF) at elevated temperature. The crystal studied contained a minor non-merohedral twin contaminant [6.3 (4)%] which was taken into account during the refinement. The coordination polyhedron of the ZrIV atom is a distorted octa­hedron [assuming that the five-membered ring of the indenyl group (Cp) occupies one coordination site], with the Cp group and a THF O atom at the apical positions and the three Cl and ligating N atoms at the equatorial positions. The Zr, Si and the methyl­ene C atoms deviate noticeably from the imidazole ring plane [by −0.197 (5), −0.207 (5) and 0.119 (6) Å, respectively]. The THF ligand adopts an envelope conformation

The Interrelationship between migration and family behaviours: internal migration within China and international migration from China to the U.S.

The dissertation investigates the interrelationship between migration and family behaviours, marriage and fertility, in the Chinese context. I apply event history techniques using data from an ethno-survey, several national-level censuses and population sample survey. Chapter 2 explores the effect of international migration on marriage chance for males and females separately. Chapter 3 studies how international migration affects fertility under the condition that the country of origin experienced strong family policies, e.g., the one-child policy. Chapter 4 explores how spousal separation due to migration affects marital fertility at couple level. The dissertation adds an interesting country case of understanding the interrelationship between migration and family events. Moreover, it accounts for the correlation between events due to unobserved characteristics. Lastly, it emphasizes the importance of socio-economic status in shaping the migration and family dynamics.La investigació tracta la interrelació entre la migració i els comportaments familiars, el matrimoni i la fertilitat, en el context xinès. S’apliquen tècniques d’història de l’esdeveniment, mitjançant l’ús de dades d’una enquesta etnogràfica, diversos censos de nivell nacional i enquestes de mostres de població. El capítol 2 explora l’efecte de la migració internacional sobre la possibilitat de contraure matrimoni tant per a homes i dones. El capítol 3 estudia com la migració internacional afecta la fertilitat, en aquelles persones que el seu país d’origen tingui polítiques familiars fortes, per exemple, la política d’un únic nen a la Xina. El capítol 4 explora com la separació conjugal causada per la migració afecta la fertilitat a nivell de parella. La investigació afegeix un cas interessant per a la comprensió de la interrelació entre migració i esdeveniments familiars. A més, representa la correlació entre els esdeveniments a causa de les característiques no observades. Finalment, l’estudi destaca la importància de l’estatus socioeconòmic en la configuració de la migració i la dinàmica familiar