•Synthesis and characterization of benzyl silanes with intramolecular ammonium group.•Structures has been elucidated by single-crystal X-ray analysis.•Change of bond lengths and angles due to polarization effects.•Determination of the electronic structure by DFT calculations and NBO analysis.•Bent’s rule as a theoretical basis for the discussion.Three benzyl silanes, 1-(benzyldimethylsilyl)methyl-1-methylpiperidin-1-ium iodide (1), 1(dibenzylmethylsilyl)methyl-1-methylpiperidin-1-ium iodide (2) and 1-(2-(benzyldimethyl-silyl)ethyl)-1-methylpiperidin-1-ium iodide (3), have been synthesized and structurally characterized by X-ray crystallography. Compounds 1 and 2 are evaluated to determine what structural influence the positive charge in α-position to silicon has on the silicon atom. Furthermore, the compound 3 is used to compare this effect and to show the structural and electronic differences in comparison to 1 and 2. DFT calculations were performed to investigate the individual electronic environments of the silicon and surrounding atoms in detail, which are discussed in regards to Bent’s rule (Bent, 1960, 1961).Three new benzyl silanes have been prepared und characterized by single-crystal X-ray analysis. The influence of an intramolecular ammonium group was investigated regarding the bonding situation of the benzyl silane unit. From the viewpoint of Bent’s rule solid state structures and DFT/NBO analysis of these compounds are discussed.

The parent compound 1,3-dithiolane L1 reacts with CuI providing the 2D coordination polymer (CP) [{Cu(μ2-I)2Cu}(μ2-L1)2]n (CP1). The Cu⋯Cu distance within the Cu(μ2-I)2Cu rhomboid is temperature-dependent and shrinks from 2.9081(7) (294 K) to 2.8743(5) (100 K). The 1D polymeric compound [{Cu(μ2-Br)}(μ2-L1)]n (CP2) was isolated upon treatment of CuBr with L1 in MeCN solution. Likewise, treatment of L1 with CuCl in a 1:1 ratio results in formation of the unusual 1D CP [{Cu(μ2-Cl)}(μ2-L1)]n (CP3). In contrast to CP1 incorporating dinuclear Cu(μ2-I)2Cu units as connection nodes, the isolated Cu atoms of CP2 and CP3 are bridged by a single μ2-Br or μ2-Cl ligand giving rise to infinite [Cu(μ2-X)Cu]n ribbons. Reaction of ferrocenecarbaldehyde with 1,2-ethanedithiol affords the crystallographically characterized ferrocenyl-dithiolane Fc-C(H)S2C2H4 (L2). L2 was used as organometallic dithioether ligand to assemble, upon treatment with CuI, the original luminescent 1D CP [{Cu2(μ4-I)(μ2-I)}(μ2-L2)]n (CP4), in which both S atoms of one L2 molecule span two copper centers of a meander-shaped infinite (CuI)n ribbon. Upon reaction of L2 with CuBr in a 1:2 ratio, the discrete tetranuclear cluster [{Cu4(μ2-Br)2(μ3-Br)2}(μ2-L2)2(MeCN)2] (CL1) is formed.

AbstractDescribed herein is a selective way to control the reaction of allylic amines with metalorganic bases depending on the amine handle as well as the metalorganic base is used. Depending on the number of coordinating groups within the amine handle either a selective carbometalation or deprotonation reaction can be performed. By changing the alkali metal within the base from lithium to either sodium or potassium, a change of chemoselectivity takes place and the reaction of piperidinoallylamine can be controlled.

AbstractThe reaction of benzyl lithiums is an important aspect in organic and organometallic synthesis. Reported herein are detailed insights into the reactivity of benzyl lithiums as regulated by intermediate structures. By discussing the carbometalation of allylamines and the reaction of the formed benzyl-lithium compounds with electrophiles, the influence of the metal as well as the solvent on the electronic structure of the intermediate is described. This molecular structure strongly influences the reactivity of these intermediates. By choosing the appropriate reaction conditions, the regioselectivity of reactions with electrophiles can be regulated. With trimethylchlorosilane in n-pentane a selective reaction at the para-position takes place. In contrast, selective reaction at the benzylic position, with trimethylchlorostannane in tetrahydrofuran (THF) as a solvent, is accomplished.

The (piperidinomethyl)silylmethyl group in the palladacycles presented here offers one of the largest differences between the trans influence of both donor atoms present. This allows studying distortions of the coordinated 1,5-cyclooctadiene or cyclopentadienyl (Cp) ligands. In the latter case, a strong distortion toward η3-Cp is detected.

A series of monomeric coordination compounds containing zinc(II) chloride or zinc(II) bromide and the 1,2-diamine ligands TMEDA, TEEDA, (R,R)-TMCDA, (R,R)-TECDA and cis-TMCDA have been synthesised and structurally characterised using X-ray diffraction analysis. All but one complex could be successfully used as initiators for the solvent-free ring-opening polymerisation of d,l-lactide. In particular, the polylactide (PLA) prepared with compounds containing (R,R)-TECDA is obtainable in high yields with molecular weights suitable for industrial applications. Thus a class of stable, easy to synthesise and efficient PLA catalysts with neutral ligands is introduced.Graphical abstractA series of monomeric coordination compounds containing zinc(II) chloride or zinc(II) bromide and the 1,2-diamine ligands TEEDA, (R,R)-TMCDA, (R,R)-TECDA and cis-TMCDA were synthesised, structurally characterised and could be successfully used as highly stable initiators for the solvent-free ring-opening polymerisation of d,l-lactide.Highlights► Synthesis and structural characterisation of six diamine-zinc complexes. ► Unexpected reactivity in ring-opening polymerisation of lactide. ► Great robustness against industrial conditions of lactide polymerisation. ► Low-priced starting materials for green polymerisation chemistry.