Synthesis of a Large Functional Cage Compound Based on Four GaGa Single Bonds and Its Application as an Oligoacceptor: On the Way to Bio‐Organogallium Hybrid Molecules

Abstract

The digallium compound R(2)Ga-GaR(2) (1; R=CH(SiMe(3))(2)) reacts with citracinic acid by the release of two equivalents of bis(trimethylsilyl)methane and the formation of a unique oligofunctional cage compound (2). Four Ga-Ga bonds in a tetrahedral arrangement are bridged by four spacer ligands that are located on the faces of the tetrahedron and bridge the gallium atoms of three different Ga-Ga bonds. Four pyridinium groups result from the shift of one of the three acidic protons of four citracinic acid molecules to the nitrogen atoms of the aromatic rings. The N-H groups are arranged in pairs and are capable of acting as chelating acceptors for the coordination of THF molecules (2(THF)(2)) or the nitrogen atoms of 1-deazapurine (3(OEt(2))(4)). In particular, the last reaction verifies the potential applicability of this relatively water- and air-resistant acceptor compound for the generation of bioorganometallic hybrid molecules.

A pH dependent Raman and surface enhanced Raman spectroscopic studies of citrazinic acid aided by theoretical calculations

“…In crystal engineering of metal-organic frameworks, the molecule also plays a crucial role. Very recently it has been used for the synthesis of an oligofunctional cage compound having four Ga-Ga bonds decorated in a tetrahedral arrangement [25]. The ligand also serves as a molecular tecton for the synthesis of three-dimensional coordination frameworks with unique topology [26].…”

Supramolecular Chemistry Based on Gallium–Gallium Single Bonds – Formation of Large Heterocycles and Cages with up to Twelve Gallium Atoms

“…One terminal CH(SiMe 3 ) 2 group of each gallium atom was replaced by a second metal atom to generate a cage compound, in which Only two carboxylatedigallium compounds with a three-dimensional arrangement of four or six Ga-Ga bonds have been reported in the literature. [9,10] They have spacer ligands with a Y-shaped arrangement of the donor atoms, which may be an important prerequisite for the formation of such cages. The acids 4 and 5 (Scheme 1) fit reasonably well into this scheme, and their treatment with 1 afforded in surprisingly selective transformations two new cage compounds with six Ga-Ga bonds (9·THF and 10·THF, yields ca.…”

“…[8] This surprising observation allowed the selective synthesis of unprecedented heterocycles or cages. Particularly interesting were reactions with trifunctional acids such as citracinic acid or benzotriazol-5-carboxylic acid which gave compounds with four [9] or six Ga-Ga bonds [10] in single molecules. The first compound had a highly functional surface, which allowed the coordination of bases such as desazapurine by hydrogen bonding, the latter had a large central cavity and irreversibly encapsulated a THF molecule which showed unusual chemical shifts in the 1 H NMR spectrum (δ = -1.2 to -3.6) caused by the vicinity of its hydrogen atoms to aromatic rings of the spacer ligands.…”

Anorganische Chemie 2011

“…Neuartige Oligoakzeptoren auf der Basis von Galliumkäfigverbindungen (30), in denen Ga‐Ga‐Bindungen als Templat fungieren, führen den schon in den letzten Jahren begonnenen Trend fort. Vier N‐H‐Bindungen der Pyridiniumgruppen in diesen Käfigen erlauben über Wasserstoffbrückenbindungen die chelatisierende Koordination von Gastmolekülen wie Ether, 1‐Deazapurin und anderen Donormolekülen 1_46…”