Hypervalent organobismuth(iii) carbonate, chalcogenides and halides with the pendant arm ligands 2-(Me2NCH2)C6H4 and 2,6-(Me2NCH2)2C6H3

R2BiOH (1) [R = 2-(Me2NCH2)C6H4] and (R2Bi)2O (2) are formed by hydrolysis of R2BiCl with KOH. Single crystals of were obtained by air oxidation of (R2Bi)2. The reaction of R2BiCl and Na2CO3 leads to (R2Bi)2CO3 (3). 3 is also formed by the absorption of CO2 from the air in solutions of 1 or 2 in diethyl ether or toluene. (R2Bi)2S (4) is obtained from R2BiCl and Na2S or from (R2Bi)2 and S8. Exchange reactions between R2BiCl and KBr or NaI give R2BiX [X = Br (5), I (6)]. The reaction of RBiCl2 (7) with Na2S and [W(CO)5(THF)] gives cyclo-(RBiS)2[W(CO)5]2 (8). cyclo-(R'BiS)2 (9) [R' = 2,6-(Me2NCH2)2C6H3] is formed by reaction of R'BiCl2 and Na2S. The structures of were determined by single-crystal X-ray diffraction.     

Tri- and Tetranuclear Metal-String Complexes with Metallophilic d10–d10 Interactions

The reaction of 2,6-F₂C₆H₃SiMe₃ with Ph₂PLi provided 2,6-(Ph₂P)₂C₆H₃SiMe₃ ( 1 ), which can be regarded as precursor for the novel anionic tridentate ligand [2,6-(Ph₂P)₂C₆H₃]⁻ (PCP)⁻. The reaction of 1 with [AuCl(tht)] (tht=tetrahydrothiophene) afforded 2,6-(Ph₂PAuCl)₂C₆H₃SiMe₃ ( 2 ). The subsequent reaction of 2 with CsF proceeded with elimination of Me₃SiF and yielded the neutral tetranuclear complex linear-[Au₄Cl₂(PCP)₂] ( 3 ) comprising a string-like arrangement of four Au atoms. Upon chloride abstraction from 3 with NaBAr^F₄ (Ar^F=3,5-(CF₃)₂C₆H₃) in the presence of tht, the formation of the dicationic tetranuclear complex linear-[Au₄(PCP)₂(tht)₂](BAr^F₄)₂ ( 4 ) was observed, in which the string-like structural motif is retained. Irradiation of 4 with UV light triggered a facile rearrangement in solution giving rise to the dicationic tetranuclear complex cyclo-[Au₄(PCP)₂(tht)₂](BAr^F₄) ( 5 ), which comprises a rhomboidal motif of four Au atoms. In 3 – 5 , the Au atoms are associated by a number of significant aurophilic interactions. The atom-economic and selective reaction of 3 with HgCl₂ yielded the neutral trinuclear bimetallic complex [HgAu₂Cl₃(PCP)] ( 6 ) comprising significant metallophilic interactions between the Au and Hg atoms. Therefore, 6 may be also regarded as a metallopincer complex [ClHg(AuCAu)] between Hg^II and the anionic tridentate ligand [2,6-(Ph₂PAuCl)₂C₆H₃]⁻ (AuCAu)⁻ containing a central carbanionic binding site and two “gold-arms” contributing pincer-type chelation trough metallophilic interactions. Compounds 1 – 6 were characterized experimentally by multinuclear NMR spectroscopy and X-ray crystallography and computationally using a set of real-space bond indicators (RSBIs) derived from electron density (ED) methods including Atoms In Molecules (AIM), the Electron Localizability Indicator (ELI-D) as well as the Non-Covalent Interaction (NCI) Index.     

Antennal sensilla of the ground beetle Bembidion properans Steph. (Coleoptera, Carabidae)

The arrangement of antennal sensilla was studied in female and male ground beetles Bembidion properans Steph. (Coleoptera, Carabidae) using scanning electron microscopy. The filiform antennae, 1.8-1.9 mm in length, consist of the scape, pedicel and nine flagellomeres. In both sexes, three types of sensilla chaetica, two types of sensilla trichodea, six types of sensilla basiconica, one type of sensilla coeloconica and one type of sensilla campaniformia were distinguished. The possible function of the sensilla is discussed and three types of sensilla are considered olfactory, sensilla trichodea type 2 and sensilla basiconica types 1 and 2. Olfactory sensilla form dorsal and/or ventral sensillar fields on the flagellomeres and occur sparsely or not at all outside these areas. No sexual differences in the types, number and distribution of antennal sensilla were found.     

Interaction of 1,2,5-chalcogenadiazole derivatives with thiophenolate: hypercoordination with formation of interchalcogen bond versus reduction to radical anion

According to the DFT calculations, [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (4), [1,2,5]selenadiazolo[3,4-c][1,2,5]thiadiazole (5), 3,4-dicyano-1,2,5-thiadiazole (6), and 3,4-dicyano-1,2,5-selenadiazole (7) have nearly the same positive electron affinity (EA). Under the CV conditions they readily produce long-lived π-delocalized radical anions (π-RAs) characterized by EPR. Whereas 4 and 5 were chemically reduced into the π-RAs with thiophenolate (PhS(-)), 6 did not react and 7 formed a product of hypercoordination at the Se center (9) isolated in the form of the thermally stable salt [K(18-crown-6)][9] (10). The latter type of reactivity has never been observed previously for any 1,2,5-chalcogenadiazole derivatives. The X-ray structure of salt 10 revealed that the Se-S distance in the anion 9 (2.722 ?) is ca. 0.5 ? longer than the sum of the covalent radii of these atoms but ca. 1 ? shorter than the sum of their van der Waals radii. According to the QTAIM and NBO analysis, the Se-S bond in 9 can be considered a donor-acceptor bond whose formation leads to transfer of ca. 40% of negative charge from PhS(-) onto the heterocycle. For various PhS(-)/1,2,5-chalcogenadiazole reaction systems, thermodynamics and kinetics were theoretically studied to rationalize the interchalcogen hypercoordination vs reduction to π-RA dichotomy. It is predicted that interaction between PhS(-) and 3,4-dicyano-1,2,5-telluradiazole (12), whose EA slightly exceeds that of 6 and 7, will lead to hypercoordinate anion (17) with the interchalcogen Te-S bond being stronger than the Se-S bond observed in anion 9.     

Production of negatively charged fragments in collisions of swift positive hydrogen ions with molecules

A first detection and analysis of negatively charged fragments produced in collisions of fast (20–150 keV) positive hydrogen ions (H⁺, H ₂ ⁺ and H ₃ ⁺ ) with gas-phase molecules is presented. The fragments and their abundances were determined by means of a time-of-flight mass spectrometer. Negative ions did emerge from every investigated target molecule species, such as halomethanes, sulfur hexafluoride, propane and propene, but in all cases with distinctly lower probability (cross sections in the range 10^?20?10^?18 cm²) than positively charged fragments (approximately on the scale 10^?3 or even less). Another essential result is that stable collisionally induced negative fragments are mostly monatomic ions, whereas positive fragments are in their majority more complex polyatomic ions. Furthermore, we observed a direct electron capture from a positively charged but not totally stripped projectile (here: H ₂ ⁺ and H ₃ ⁺ ) into stable or very longlived states of the molecular ions SF ₆ ^? and O ₂ ^? , the latter with the largest cross section (10^?18?10^?17 cm²) found up to now.     

Novel and facile synthesis of fluorinated enamino ketones and amino alcohols

Selected imines and one bis-imine react via their enamine tautomers with terminal perfluorinated epoxides, e.g. hexafluoropropene oxide to produce fluorinated enamino ketones or imino ketones. In contrast, internal perfluorinated linear epoxides and one cyclic epoxide yield intermediate imino alcohols, which in one case added hexafluoroacetone, furnishing a new imino diol investigated by X-ray diffraction.