Preparation of aminomethyl functionalised silanes via an α-lithiated amine: from their synthesis, stability and crystal structures to stereochemical issues

Synthesis and crystal structure of [Zn6Br4(C9H18NO)4(OH)4]·2C3H6O2

The complete molecule of the hexametallic title complex, namely, tetrabromidotetra-μ-hydroxido-hexakis[μ-2-methyl-3-(pyrrolidin-1-yl)propan-2-olato]hexazinc(II) acetone disolvate, [Zn6Br4(C9H18NO)4(OH)4]·2C3H6O2, is generated by a crystallographic centre of symmetry. Two of the unique zinc atoms adopt distorted ZnO2NBr tetrahedral coordination geometries and the other adopts a ZnO3N tetrahedral arrangement. Both unique alkoxide ligands are N,O-chelating and both hydroxide ions are μ2 bridging. The crystal structure displays an O—H...O hydrogen bond between a μ2-OH group and an acetone solvent molecule. The Hirshfeld surface has been calculated and is described.

Crystal structure of borated N,N,N',N'-tetra-methyldi-amino-methane

In the title compound, {[(di-methyl-amino)-meth-yl]di-methyl-amine}-trihydridoboron, C5H17BN2, the tetra-hedral geometry of the N-C-N unit is slightly disorted. As a result of the bulky amine substituents, a wider N-C-N angle of 113.6 (1)° is observed. The bond lengths between the N atom and methyl groups are slighly elongated to 1.481 (2) and 1.482 (2) Å at the borated N atom, whereas the distances between the other N atom and its methyl groups are only 1.461 (2) and 1.462 (2) Å. The studied crystal was twinned. The twin data refinement was subsequently carried out with a scale factor of 0.263 (1). The two lattices of the twin domains were rotated by 179.84°.

Exploring the synthesis of a new group of chiral ammonium salts with specific configurations at the stereogenic nitrogen centers

A group of new chiral dications with a fixed, specific configuration at the stereogenic nitrogen center was created. Stereoselective synthesis and recrystallization give the diastereomerically and enantiomerically pure dications, including a chiral amphiphile with surface-active properties.

Formation of specific configurations at stereogenic nitrogen centers upon their coordination to zinc and mercury

The coordination of (R,R)-tetramethylcyclohexane-1,2-diamine derivatives with stereogenic nitrogen centers to zinc and mercury halides is investigated. It is shown that the resulting complexes display one specific configuration at the stereogenic nitrogen centers. This fact is unusual due to the fast inversion of nitrogen centers but highly desirable as the stereoinformation of the ligands is brought closer to the metal centers of the potential catalysts. A combination of NMR studies and quantum chemical calculations gives insight into the selective formation of one specific configuration at the stereogenic nitrogen centers of the zinc complexes.