The generation, growth, and properties of homo- and heteronuclear clusters in the vapor phase are a fascinating area of research, where new insights into structure have been gained, especially from mass spectrometric investigations. True, the demarcation of molecules, clusters and microcrystals is important, yet there also exist relationships between clusters in the vapor phase on the one hand and molecules in solution and solids on the other.

Glycopeptides, glycolipids, and glycophospholipids are of special interest as components of membranes. The oligosaccharide residue is, inter alia, responsible for intercellular recognition and interaction (immuno-reactions). Major advances have been made in the synthesis of oligosaccharide, largely due to 1-O-alkylation, the trichloroacetimidate method, and activation via glycosylsulfonium salts.

Exploitation of an old and frequently studied reaction (to obtain new compounds) has proven successful with the system PCl₃/P(NMe₂)₃/AlCl₃. Depending on the sequence in which the reaction partners are allowed to react with each other, different products are formed. The most interesting new products are the diphosphoniodiphosphirane ion 1 (the CH₂ group comes from the solvent CH₂Cl₂) and the cyclotetraphosphane ion 2.

Five metal atoms and seven cyclopentadienyl ligands are present in the novel complex 1, which is formed on reaction of [Cp₂Ti(CO)₂] with [CpCo(C₂H₄)₂].CO is therby reduced to .

The oxidation of diphenylcarbene 1 to benzophenone O-oxide 2 with molecular oxygen has been elucidated by a matrix isolation technique. 2 is stable in the matrix at 10K and can be detected spectroscopically. The well-known chemiluminescence is observed in the reaction of 2 with 1.

Examination of the porhyrins from the viewpoint of the “annulene chemist” has led to the discovery of the novel, simple porphin isomer porphycene 2. The path from conception to the synthesis of the molecule was surprisingly short. 2 is formed as a stable compound upon McMurry reaction of 1.

Useful intermediates for the preparation of optically active 2-arylalkanoic acids and aryl-1-bromoethyl ketones, the α-bromoacetal 1 and its 1′R-diastereomer, are formed in the ratio ≥ 90: ⩽ 10 in the title reaction. Compounds of this type are of special interest, among other things, as precursors of antiinflammatory drugs.

The metal-dependent transition between intra- and intermolecular CH addition has been studied with the title reaction as example: With cis-H₂Fe(pp₃), the cyclometalated compound 1 is formed, with cis-H₂Ru(pp₃) the phenyl hydride 2. A decisive factor might be the difference in size of the metal atoms, which leads to different crowding of the groups and different chelate ring strain ((pp₃ = P(CH₂)₃PMe₂)₃).

S₂O₂, the unstable initial product of SO decomposition in the gas phase, has been trapped for the first time by complexation. With the isolation of the surprisingly stable thiirane S-oxide complex 1, it was further demonstrated that C₂H₄SO first decomposes after coordination to a metal. Ethylene is eliminated from 1 in toluene only at 110°C, whereupon the S₂O₂ complex 2 is formed.

A planar Cu₃Os₃ framework forms the core of the title compound, which can be synthesized via two routes. Noteworthy is its isolation from [HCuPPh₃] and [H₄Os(PMe₂Ph)₃] with elimination of PPh₃ and H₂. Inspection of the structure of the cluster (Figure on the right, metal atoms hatched), shows that the Os atoms are shielded by the phosphane ligands, but the Cu atoms are accessible through a tunnel of phenyl and methyl groups.

No, but a 2-phosphapropane, is the answer to the question posed in the title. H₃CPCH₂ 1 can be generated by gas-phase pyrolysis from (CH₃)₂PCl 2 and characterized by PE and mass spectrometry. Whereas the first ionization in the case of normal phosphorus ylides occurs between 5.95 and 6.85 eV, in the case of 2 it first takes place at 9.69 eV. According to an MNDO calculation of the PE spectrum of 1, the answer to the “Hamlet” question “to d or not to d” (i.e. whether d orbitals participate in the PC bonding) is no.

The first real cyclohexatriene derivative, the title compound 2, has been characterized by an X-ray structure analysis. In the key step of the new, productive synthesis, the triyne 1 is cyclized in the presence of the catalyst [(C₅H₅)Co(CH₂CH₂)₂].

A molecule that doesn't require any introduction, the title compound 1, can be precipitated as a white powder; solutions in polar solvents are stable. 1 forms transition-metal complexes. The ethynyl groups in the precursors with six Me₃SiCC groups on the benzene ring are not exactly linear (X-ray structure analysis).

A host of new, synthetically valuable 2-epoxy alcohols 3 should be accessible by the generally applicable title reaction. Oxygen transfer from 1 does not proceed intramolecularly; the first step is the formation of the allylic alcohol 2, which is epoxidized in a rapid secondary step by 1 to the product 3. At the same time, compound 2 is reformed.

A further analogy between inorganic and organic chemistry is found in the reaction of the rhenium complex 1 with alkali metal chalcogenides, which leads to the compounds 2 to 4. These were characterized by an X-ray structure analysis. This reaction corresponds to the alkylation of chalcogenides. Re(CO) (16e) and carbenium ions R₃C^⊕ are isolobal.

Re-S compounds should be even better catalysts for the desulfurization of crude oil than the long proven MoS compounds. The first step in the development of a catalyst, the synthesis of a discrete ReS cluster anion, has now been accomplished. Reaction of a perrhenate solution reduced with NH₂OH·HCl with an aqueous polysulfide solution yielded an NH₄-salt of the cluster anion [Re₄S₂₂]⁴⁻ 1.

Isomerization to optically active cyclic vinyl ethers 2 has been accomplished with the cyclic allyl ethers 1 in the presence of chiral Ru or Rh catalysts. The magnitude of the ee value (at present up to 25%) depends on the substituents R.

A new form of coordination of the versatile ligand hexathia[18]crown-6 is found in the title compounds: Pd or Pt is coordinated to four S atoms in a square planar fashion; only long range weak axial interactions are observed with the two remaining S atoms of the macrocycle. That is, the macrocycle does not behave like a crown ether.

Carrying out an X-ray structure analysis of a substance melting at −112°C is no easy task. However, the effort put into accomplishing such an analysis of ethylene oxide has been worthwhile, since the result is surprising: In the crystalline state the carbon atoms and the oxygen atoms in ethylene oxide 1 form an almost equilateral triangle with CC and CO bond lengths of ca. 143 pm. This is other than what was found in earlier investigations of ethylene oxide in the liquid and gaseous states.

Excellent ligands for an affinity chromatography of angiotensin converting enzyme have been found, namely the new inhibitors of this enzyme such as 1, R¹, R²H, alkyl. They were prepared from N^ε-Boc-L-lysine methyl ester and α;-trifluoromethanesulfonyloxycarboxylic esters. Inhibitors of this enzyme are of pharmaceutical importance.

The first Dewar phosphabenzenes, which at the same time contain the first four-membered ring with a PC double bond, namely the title compounds 1, are surprisingly stable towards heat and oxygen. 1, R¹=Me, R²=1-adamantyl, has been characterized by an X-ray structure analysis.

Do the absorption maxima of the cyanines 1–3 shift in dependence of the position of the counterions? In C₂H₅OH and CH₂Cl₂ no such interaction could be established. This finding should contribute, inter alia, to an understanding of the role of the natural bacteriorhodopsins.

The “special pair” of bacteriochlorophyll molecules in the reaction center of bacterial photosynthesis is immediately recalled to mind by two properties of the title compounds (cf. right): (1) The stable radical cation exhibits strong absorption in the near infrared; (2) the redox potential of this oxidation lies well below that of the corresponding magnesium monotetrapyrrole.

Polar solvents enhance the anomeric effect. This surprising turnabout follows from the NMR data and calculated dipole moments of dioxane derivatives such as 1 and 2. Accordingly, polar solvents stabilize the diaxial conformation in 2, RSiMe₃, tBu; in these compounds μ_eq ≈ μ_ax. Contributions by quadrupole moments etc. Were not taken into account.

A universally modifiable new starting substance, the fulvalene Zr^III complex 1, is formed upon reaction of Cp₂ZrCl₂ and sodium amalgam. 1 is highly reactive, but nevertheless it can be isolated. The fulvalene ligand ensures that the secondary products are dinuclear, e.g. [(CpZrCl)₂(C₅H₄₋C₅H₄)O], the oxidation product of 1.