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Treatment of the dimethylamino-[3]ferrocenophane 1a with B(C6F5)3 results in hydride abstraction at the −CH(NMe2) moiety in α-position to the ferrocene nucleus to yield the corresponding cation 4a. The X-ray crystal structure analysis of the salt 4a·[HO{B(C6F5)3}2 -] has revealed a residual Fe−Cα interaction even in this case of a strongly substituent-stabilized α-ferrocenyl carbenium ion. A DFT calculation of a series of derivatives containing nitrogen substituents of a decreasing ability for carbenium ion stabilization (4a, −NMe2; 4b, −pyrrolyl; 4c, −triazolyl) revealed a markedly increased Fe−C interaction with decreasing C+ stabilization by the hetarene substituents.

[3]Ferrocenophanone rac-8 was prepared by several non-Friedel-Crafts pathways starting from a Mannich-type coupling of 1,1'-diacetylferrocene followed by catalytic hydrogenation. Hydride abstraction from the resulting alpha-dimethylamino[3]ferrocenophane rac-14 with B(C6F5)3 followed by hydrolysis gave the ketone rac-8. Several variants of the Sommelet reaction, using ethylglyoxylate, formaldehyde or hexamethylenetetramine (urotropine) as the "oxidizing" reagent gave the alpha-[3]ferrocenophanone 8 in good to excellent yield. Some variants of these reactions were also used for the preparation of the pure enantiomer (R)-8. The electrochemical behaviour of 8 has been investigated and compared with related derivatives.

Abstract. The IceCube Neutrino Observatory instruments about 1 km3 of deep, glacial ice at the geographic South Pole using 5160 photomultipliers to detect Cherenkov light emitted by charged relativistic particles. A unexpected light propagation effect observed by the experiment is an anisotropic attenuation, which is aligned with the local flow direction of the ice. Birefringent light propagation has been examined as a possible explanation for this effect. The predictions of a first-principles birefringence model developed for this purpose, in particular curved light trajectories resulting from asymmetric diffusion, provide a qualitatively good match to the main features of the data. This in turn allows us to deduce ice crystal properties. Since the wavelength of the detected light is short compared to the crystal size, these crystal properties do not only include the crystal orientation fabric, but also the average crystal size and shape, as a function of depth. By adding small empirical corrections to this first-principles model, a quantitatively accurate description of the optical properties of the IceCube glacial ice is obtained. In this paper, we present the experimental signature of ice optical anisotropy observed in IceCube LED calibration data, the theory and parametrization of the birefringence effect, the fitting procedures of these parameterizations to experimental data as well as the inferred crystal properties.

A macrocycle, 6, has been synthesized in high yield from 2,5-di(pyrazol-1-yl)hydroquinone and 1,1′-fc[B(Me)NMe 2 ] 2 {fc ) Fe(C 5 H 4 ) 2 }. The molecule incorporates two redox-active 1,1′ferrocenylene units in its backbone and contains four chiral boron centers, each of them possessing the same configuration. It is demonstrated that crystal structures of organometallics of moderate complexity can be solved from high-resolution X-ray powder diffraction patterns, once the connectivity between the functional groups is known.