Poly(di(ω-alkylphenyl)stannane)s

Poly(di(ω-alkylphenyl)stannane)s, [Sn(C n H2n Ph)2] m with n=2-4, and a copolymer of di(3-propylphenyl)stannane and dibutylstannane of weight-average molar masses of 2-8·104g/mol were synthesized by dehydropolymerization of stannanes of the composition H2SnR2 using Wilkinson's catalyst [RhCl(PPh3)3]. At least two methylene groups were required as spacers between the phenyl group and the tin atom for polymerization to occur. The polystannanes were characterized by, among other techniques, 1H, 13C and 119Sn NMR spectroscopy, thermal analysis and X-ray diffraction. The polymers featured properties different from those of the corresponding poly(dialkylstannane)s. Specifically, the [Sn(C n H2n Ph)2] m family displayed glass transitions at remarkably low temperatures, down to ca. −50°C, and a lower value for a copolymer (−68°C). Polymers [Sn(CnH2nPh)2]m with n=2 and 3 and a copolymer at room temperature were of a gel-like concistence, which enabled facile orientation with shear forces. Finally, the temperature-dependent electrical conductivity was determined for poly(di(3-propylphenyl)stannane), which followed the law of typical semiconductors, with an activation energy for conduction of 0.12e

Regionalisierung und Regionsbildung im Norden

Die raumplanerische Debatte um regionale Handlungsebenen war in Deutschland in den letzten Jahren stark auf die Metropolregionen konzentriert. Dieser Band nimmt den Diskurs um Regionsbildungsprozesse auf mittlerer Ebene, der bereits in den 1990er Jahren intensiv geführt worden ist, wieder auf. Es geht darum, zum einen nachzuzeichnen, welche Gemeinsamkeiten und Unterschiede sich in den Regionalisierungsansätzen der beiden Bundesländer Niedersachsen und Schleswig-Holstein zeigten, und zum anderen die Stände der Regionsbildungsprozesse in insgesamt vier Regionen gegenüberzustellen. Im Ergebnis werden vor allem die unterschiedlichen Entwicklungsstände der Regionen innerhalb eines Lebenszyklus regionaler Kooperation deutlich. Während die Region Nord sich noch in der Mobilisierungs- und Zielfindungsphase befindet, ist die K.E.R.N.-Region bereits am Ende des Lebenszyklus angelangt, d.h. in einer Auflösungsphase. Die Region "Emsland-plus" durchläuft die Arbeits- und Entwicklungsphase, während die Region Göttingen um den Übergang zur weiteren Stabilisierung und regionalen Integration ringt. Die Ergebnisse der Untersuchungen lassen auch Rückschlüsse auf die Regionsbildungspolitiken der beiden nordwestdeutschen Flächenländer zu.Over recent years the debate within spatial planning in Germany on regional levels of action has been concentrated particularly on metropolitan regions. This collection of papers revives the discourse on processes of region building at the intermediate level, which was already a matter of intensive debate in the 1990s. The underlying intention is, firstly, to identify and trace any commonalities and differences in the approaches to regionalisation adopted in the federal states of Lower Saxony and Schleswig-Holstein, and, secondly, to compare and contrast the current state of region-building processes in a total of four regions. What becomes particularly evident is the differing stages of development which have been reached within a life cycle of regional co-operation in the various regions. Whilst "Region Nord" still finds itself at the stage of mobilisation and goal-setting, the "K.E.R.N. Region" has already reached the end of the life cycle, i.e. the dissolution phase. The "Emsland-plus" region is currently at the work and development stage, whereas the Göttingen region is struggling to make the transition to greater stability and regional integration. The findings of the studies reported also allow various conclusions to be drawn regarding the region-building policies in place in these two federal states of northwestern Germany