Beiträge zur Chemie der Halogensilan‐Addukte. XIV. Neutralligand‐Komplexe des Siliciums mit sechs N‐Donoratomen

Abstract

[Si · 3 bipy]4+ wird in hoher Ausbeute durch Oxydation von Si · 3 bipy mit Halogen erhalten. Die Darstellung von [Si · 3 bipy]I4 gelingt auch durch direkte Reaktion von SiI4 und bipy in der Schmelze. Mit phen wird unter gleichen Bedingungen [Si · 3 phen]I4 gebildet. 1‐Methyl(Vinyl)‐imidazol (mimi, vimi) und 1,1′‐Dimethyl‐2,2′‐diimidazol (dimi) reagieren mit SiI4 in CHCl3 zu [Si · 6 L]I4 (L = mimi, vimi) und [Si · 3 dimi]I4. Mit Thiazol, Pyridin und 4‐Dimethyl‐aminopyridin werden 1:4 Komplexe, mit Isoxazol keine Reaktion erhalten. Die Komplexstöchiometrie hängt von Basizität und Struktur der Liganden ab. Die 1:4 Komplexe sind hydrolyseempfindlich, die N‐hexakoordinierten Komplexe sehr solvolysebeständig. Sie sind unzersetzt in Wasser löslich. Spektroskopische Untersuchungen (IR, UV, 1H‐NMR) weisen für die festen und gelösten Titelverbindungen oktaedrische Komplexkationen der Ladung 4+ entsprechend den gegebenen Formeln nach. Über Ionenaustauscher ist vollständiger Anionenaustausch möglich. Mit dieser Methode werden die Komplexe [Si · 6(3)L](ClO4)4 dargestellt.

Charged and Betainic Nucleobases. On Syntheses and Properties of First Mesomeric Uracilylbetaines, Uracilates, and Novel Uracilium Salts

“…However, ab initio calculations and experimental data lend strong support to O(4) as coordination site of metals. In order to avoid competing reactions such as complexation of the Lewis acid by the nucleophile or its conversion into perhetarenium compounds, and as no reports on complexes of 6-chlorouracils exist, we examined the interaction of hard as well as soft Lewis acids with uracil 1 . Addition of antimony pentachloride or aluminum chloride to a solution of 1 resulted in instant formation of precipitates, whereas the crystallization of the boron trifluoride and zinc chloride complexes required concentration of the reaction mixture in vacuo and cooling.…”

Synthesis and Functionalization of Hexacoordinate (Arenediolato)bis(polypyridyl)silicon(IV) Complexes

“…[4,5] Unfortunately, the currently prevailing general concerns of metal-based toxicities inhibit the wider use of octahedral transition-metal complexes for biomedical research and therapy. [8] Yoshikawa et al later reported the resolution of these cations into their configurationally stable Λ-and Δ-enantiomers. Two years ago, we therefore started to investigate hexacoordinate silicon as a candidate to serve as a structural substitute for octahedral transition metals, and, indeed, in a proof-of-principle study we were able to demonstrate that straightforward synthesized octahedral silicon complexes can very well serve as robust, hydrolytically surprisingly stable templates for the design of bioactive compounds -in our case, hexacoordinate silicon DNA intercalators.…”

Recent advances in hexacoordinate silicon with pyridine-containing ligands: Chemistry and emerging applications

“…[43] Si(bpy)3 can be oxidized with halogens to generate the fully oxidized species, [Si(bpy)3]X4. [Si(bpy)3]I4 and [Si(phen)3]I4 were also synthesized directly by combining SiI4 with a large excess of the appropriate ligand and heating in a sealed ampoule above the melting point of the ligand for 12 hours [44]. Alternatively, the reaction of SiI4 and the appropriate ligand in pyridine or 2-methylpyridine (2-picoline) at 125 o C for 2 hours provides the corresponding hexacoordinate species [45].…”