The evaluation of UV/VIS spectra is frequently facilitated, and sometimes only becomes possible, on consideration of a higher-order derivative (preferably the 3rd, 4th, or 5th derivative) instead of the original spectrum. With aid of a new analog computer, low-noise on-line derivative spectra can now be obtained up to the 7th (or even 9th) order.

Carbene complexes, π-olefin complexes, ketene complexes, organometallic diazoalkanes, complexes with halocyclopentadienyl ligands, and many other compounds are accessible from diazoalkanes, which thus prove to be versatile reagents.

The prediction and calculation of chemical reactions is an aim of theoretical chemistry. Electrostatic models based on the virial theorem hold promise of a method for accurate and reliable prediction of ΔH and dipole moments of molecules and radicals.

Polyethylene fibrids are small, highly oriented fibers formed on shear-induced crystallization of polyethylene. They have interesting properties.

Cobalt-substituted cyclopropanes could be of significance in coenzyme B₁₂-catalyzed rearrangements. Interestingly, a cobaloxime generated in situ reacts only with the exo bromide (2) and not with the endo bromide (1) to give product (3). The retention of configuration observed in this reaction is probably due solely to shielding by the dihydrophenanthrene flank.

Tetra-tert-butyldiphosphoxane, a new complex ligand, has now been stabilized for the first time in the gold compound (2). Compound (2) was obtained from ClAuCO and tBu₂PCl via the complex (1). There is also something new to report about a related “old” ligand: the 1:2 complex of Ph₂PNMePPh₂ with AgBr contains a clamped Ag₄Br₂ octahedron.

The benzene dimer (1) having C₂ symmetry and two “isolated” double bonds attracts interest on account of its considerable stability and its suitability as a model for the study of intramolecular interactions.

“Isobenzvalene” (1), a very highly strained molecule, has now been trapped in the form of the Diels-Alder adduct (2) with anthracene. The structure of (2) is also unusual: C-11 and C-16 are both located outside the tetrahedron formed by their four substituents (“inverted tetrahedron”).

Chiral molecules without measurable optical rotation are rare. In the case of the enantiomers (1a) and (1b), which were synthesized as potential new examples, the prediction of negligible optical rotation proved to be false. The rotations of ca. −30 and +27° could be due to the twisted chair form of the rings.

The template action of chromium is held responsible for ring closure of (1) to form the complex (2). The reaction fails to occur with the homologous tungsten compound.

Pd³⁺Te²⁻I⁻, one of the extremely rare “true” palladium(III) compounds, forms brass-yellow crystals characterized, inter alia, by their good electrical conductivity. The bonding can only be described by the band model.

The two aza derivatives of 1,6-methano[10]annulene are of interest as potential heteroaromatic systems. (1) has been obtained in a multistep synthesis by Vogel et al.; the 10-methoxy (2) and 10-ethoxy derivatives of the isomer have also been prepared.

The two aza derivatives of 1,6-methano[10]annulene are of interest as potential heteroaromatic systems. (1) has been obtained in a multistep synthesis by Vogel et al.; the 10-methoxy (2) and 10-ethoxy derivatives of the isomer have also been prepared.

The recognition of K^⊕ and Na^⊕ by (membrane bound) ligands is one of the fundamental processes occurring in the living cell. The “noncyclic crown ether” (1) is an excellent model substance; the thermodynamic parameters for the formation of complexes between (1) and Na^⊕ were determined by ²³Na-NMR spectroscopy.

Cation-selective color changes can be accomplished in dyes in which a heteroatom of the chromophore participates as a donor center in complex formation by a crown ether. The greatest effect (Δλ ≈ 120nm) is observed with the combination (1), M^⊕ = Ba^2⊕ (2I⁻ as counterion).

The chemical language of the common wasp is starting to be deciphered. It protects itself from attack by fellow wasps by means of the volatile dioxaspirodecanes (1) and (2).

The directed modification of cobalt-containing clusters is possible by exchange of Co for other metals. This generalizable synthetic strategy involves attachment of an AsMe₂M(CO)₃Cp chain to Co and thermal decomposition of the product with release of an oligomer having the approximate composition [(CO)₃CoAsMe₂]_x (1); M = Cr, Mo, W.

Four different atoms at the corners of a tetrahedron are to be found in the cluster (1) (M = Cr, Mo, W). The chiral molecules were prepared from the corresponding FeCo₂ cluster by metal exchange. Their chirality can be demonstrated by ¹H-NMR spectroscopy of the PPhMe₂ derivatives of (1).

The first phosphirane oxide (1) has now been obtained by elimination of HCl from the corresponding open-chain compound. On warming, compound (1) decomposes to the alkene (2) and the phosphinidene oxide (3), which could be trapped with a o-benzoquinone derivative.

The new air-stable complexes (1), (2), and (3)—the first paramagnetic compounds of this kind—contain 31, 32, and 33 valence electrons. So far, only diamagnetic triple-decker complexes having 30 or 34 valence electrons were known. (The central ring in (1)—(3) bears one methyl and four ethyl substituents.)