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Stress tasks are used to induce sympathetic nervous system (SNS) arousal. However, the efficacy and the patterns of SNS activation have not been systematically compared between different tasks. Therefore, we analyzed SNS activation during the following stress tasks: Presentation of negative, positive, and – as a control – neutral affective pictures, Color-Word interference test (CWT), mental arithmetic under time limit, singing a song aloud, and giving a spontaneous talk. We examined 11 healthy subjects and recorded the following SNS parameters: Activation of emotional sweating by quantitative sudometry, skin vasoconstriction by laser-Doppler flowmetry, heart rate by ECG, blood pressure by determination of pulse wave transit time (PWTT), and electromyographic (EMG) activity of the trapezius muscle. Moreover, subjective stress ratings were acquired for each task using a visual analog scale. All tasks were felt significantly stressful when compared to viewing neutral pictures. However, SNS activation was not reliable: Affective pictures did not induce a significant SNS response; singing, giving a talk and mental arithmetic selectively increased heart rate and emotional sweating. Only the CWT globally activated the SNS. Regarding all tasks, induction of emotional sweating, increase of heart rate and blood pressure significantly correlated with subjective stress ratings, in contrast to EMG and skin vasoconstriction.Our results show that the activation of the SNS widely varies depending on the stress task. Different stress tasks differently activate the SNS, which is an important finding when considering sympathetic reactions - in clinical situations and in research.

A series of cyclooctatetraene bis(phosphinimino)methanide complexes of yttrium and the lanthanides, [{CH(PPh2NSiMe3)2}Ln(η⁸-C8H8)] (Ln = Y, Sm, Er, Yb, Lu), were synthesized via three different pathways. The title compounds can be obtained either from [(η⁸-C8H8)LnI(THF)3] and K{CH(PPh2NSiMe3)2} or from K2C8H8 and [{CH(PPh2NSiMe3)2}LnCl2]2. In a third approach the title compounds were synthesized in a one-pot reaction starting from K{CH(PPh2NSiMe3)2}, LnCl3, and K2C8H8. All complexes have been characterized by crystal X-ray diffraction. The solid-state structures of these complexes show that both ligands completely shield the metal center. As a result of the steric crowding, both ligands are slightly asymmetrically attached to the metal. Even though the title compounds are noncharged lanthanide complexes with no obvious leaving group and no coordinated solvent molecules, the compounds were tested as catalysts for the hydroamination/cyclization reaction. A moderate catalytic activity at elevated temperature is observed.

The monoanionic phosphine(phosphinimino)methanide ligand (Ph2PCHPPh2NSiMe3)^- is introduced in organometallic chemistry. Starting from the established compound Ph2PCH2PPh2NSiMe3 (1) the potassium salt [K(Ph2PCHPPh2NSiMe3)]n (2) was prepared. The solid state structure of 2 shows a η³-N−P−C heteroallyl coordination of the ligand as well as a π-coordination of the phenyl rings to the potassium atoms. These coordination modes lead to an infinite chain in the solid state. Compound 2 was further reacted to the samarium complex [(η⁵-C5Me5)2Sm(Ph2PCHPPh2NSiMe3)], in which the (Ph2PCHPPh2NSiMe3)^- ligand coordinates in η³-heteroallylic fashion via the N atom and the methine group to the center metal.

Reaction of K{CH(PPh2NSiMe3)2} (1) with anhydrous yttrium or lanthanide trichlorides leads to [{CH(PPh2NSiMe3)2}LnCl2]2 (Ln = Y (2a), Sm (2b), Er (2c), Dy (2d), Yb (2e), Lu (2f)). The single-crystal X-ray structures of these complexes show that the methine carbon is bound to the lanthanide atom. This is supported by DFT calculations, which show a comparable interaction. Due to the similar ion radii of the lanthanides, the single-crystal X-ray structures of 2a−f are isostructural. Further reaction of 2 with KNPh2 afforded [{CH(PPh2NSiMe3)2}Ln(NPh2)2] (Ln = Y (3a), Sm (3b)). These complexes show in comparison to 2 a similar coordination behavior of the {CH(PPh2NSiMe3)2}^- ligand in the solid state and in solution.

Sodium and potassium cyclopentadienide were obtained in an improved synthetic procedure. They were prepared in a one-pot synthesis directly by reaction of alkali metals with neat dicyclopentadiene at elevated temperature. The products precipitated as white powders and were isolated by filtration. The excess of dicyclopentadiene can be recycled. The new reaction procedure provides a much more convenient access to the products, no dry solvents such as THF or decahydronaphthalene are needed, and no colored impurities are observed.