1,4,6,10-Tetraazaadamantanes (TAADs) with -amino groups: synthesis and formation of boron chelates and host-guest complexes.

A synthetic route to 1,4,6,10-tetraazaadamantanes (TAADs) bearing free and protected amino groups at the bridge -atoms has been developed via intramolecular cyclotrimerization of C=N units in the corresponding tris(hydrazonoalkyl)amines. In a similar fashion, unsymmetrically substituted TAADs having both amino and hydroxy groups at the bridge -atoms were prepared via a hitherto unknown co-trimerization of oxime and hydrazone groups. The use of -TAAD derivatives as potential ligands and receptors was showcased through forming boron chelates and host-guest complexes with water and simple alcohols.

A large octupole magnetic trap for research with atomic hydrogen.

We describe the design and performance of a large magnetic trap for storage and cooling of atomic hydrogen (H). The trap operates in the vacuum space of a dilution refrigerator at a temperature of 1.5 K.

Efficient Photooxidation of Aryl(hetaryl)pyrazolines by Benzoquinone.

Photooxidation of aryl(hetaryl)pyrazolines in the presence of benzoquinone has been studied in organic solvents. This reaction occurs at high rate to provide the corresponding pyrazole in a good yield. The effects of the solvent, pyrazoline structure and oxygen provide definite information on the reaction pathway.

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia.

Exhaustive Michael-type alkylations of amines and ammonia with azoalkenes (generated from α-halohydrazones) were demonstrated as an efficient approach to poly(hydrazonomethyl)amines - a novel class of polynitrogen ligands. An intramolecular cyclotrimerization of C=N bonds in tris(hydrazonomethyl)amine to the respective 1,4,6,10-tetraazaadamantane derivative was demonstrated.

Urotropine isomer (1,4,6,10-tetraazaadamantane): synthesis, structure, and chemistry.

The first synthesis of 1,4,6,10-tetraazaadamantane, the C3v-symmetrical structural isomer of urotropine (1,3,5,7-tetraazaadamantane), and a series of its derivatives is reported. X-ray and quantum-chemical studies revealed remarkable distinctions in structures of urotropine and "isourotropine" cations, probably arising from different types of hyperconjugation between lone electron pairs of nitrogen atoms and σ*C-N orbitals in these heterocage systems. Since substitution at bridge and bridgehead nitrogen atoms can be easily introduced, 1,4,6,10-tetraazaadamantane may be considered as a new rigid multivalent (3 + 1) scaffold for the design of functional molecules and materials.