From an Al4-Cluster to Al+ Complexes: Lessons on Metalloidal Clustering

Low-valent aluminium compounds are among the most reactive and widely researched main-group compounds. Since the isolation of [(AlCp*)4] in 1991 as the first stable, molecular AlI compound, a variety of highly reactive neutral or anionic low-valent aluminium complexes were developed. In particular, the strongly basic aluminyl anions allowed for nucleophilic activation of a large variety of small molecules and formation of elusive transition-metal complexes. By contrast, an accessible cationic, low-valent aluminium compound combining the nucleophilicity of low-valent compounds with the electrophilicity of aluminium is hitherto unknown. Here, we report the synthesis of [Al(AlCp*)3]+[Al(ORF)4]– (RF = C(CF3)3) via a simple metathesis route. Unexpectedly, the complex ion forms a dimer in the solid state and in concentrated solutions. Addition of Lewis bases results in monomerization and coordination to the unique formal Al+ atom giving [(L)xAl(AlCp*)3]+ salts with L = hexaphenylcarbodiphosporane (cdp; x = 1), tetramethylethylenediamine (tmeda; x = 1) and 4-dimethylamino-pyridine (dmap; x = 3). Depending on the donor strength of the ligand added, the Al+–AlCp* bonds in the [(L)xAl(AlCp*)3]+ cluster cations can be finely tuned between very strong (L = nothing) to very weak and approaching isolated [Al(L)3]+ ions (L = dmap). We anticipate our easily accessible low-valent aluminium cation salts to be the starting point for investigation and potential application of this unusual compound class. In particular, the ambiphilic reactivity of the cationic, low-valent compounds will be studied. Moreover, knowledge gained from the stabilization of the reported complex salts is expected to facilitate the isolation and application of novel cationic, low-valent Al complexes.

De novo synthesis of hybrid d-f block metal complex salts for electronic charge transport applications

The advent of the d-d type of complex salts in designing smart functional materials of versatile utility inspired us to develop a novel type of M(II)-Ce(IV) complex salts [M(II) =...

ELASTOMERS WITH A HIGH CONTENT OF MODIFIED CARBOXYMETHYLCELLULOSE

The use of lactam-containing complex salts (LCS) with the functions of dispersants, apparatuses and crosslinking agents made it possible to obtain elastomers with a high (at least 300 wt.% per 100 wt.h. of rubber), containing modified carboxymethyl cellulose for the cuff of a packer device capable of performing the necessary shut-off functions in contact with highly concentrated, at least 25% aqueous solutions of mineral salts - NaCl and CaCl2. The achieved effect is expressed in the ability of LCS to disperse water-swelling polymers (GNP), to have an appreting effect on GNP particles, thereby preventing their agglomeration, as well as to create additional chemisorption bonds in the rubber matrix. As a result, a developed network of interface boundaries is obtained, which contributes to the rapid penetration of aqueous solutions of mineral salts into the array of elastomeric composition.

SYNTHESIS OF MACROCYCLES FROM COMPLEX NICKEL SALTS

Исследовано взаимодействие комплексной соли хлорида никеля (II) с диаминомочевиной в присутствии глиоксаля. Получены различные комплексные соли катионного типа на основе никеля (II) с диаминомочевиной и на их основе были синтезированы соответствующие макроциклические соединения. Полученные комплексы и макроциклы исследованы физико-химическими методами анализа. The interaction of a complex salt of nickel (II) chloride with diamino urea in the presence of glyoxal was studied. Various complex salts of the cationic type based on nickel (II) with diamino urea were obtained and the corresponding macrocyclic compounds were synthesized on their basis. The resulting complexes and macrocycles were studied by physicochemical methods of analysis.

Bismuth-rich bimetallic clusters (CuBi8)3+ and [MBi10]4+ (M = Pd, Pt) from ionothermal synthesis

The reaction of Bi, BiBr3, and CuBr in the Lewis-acidic ionic liquid [BMIm]Br·4AlBr3 (BMIm = 1-n-butyl-3-limidazolium) at 180 °C yielded air-sensitive, shiny black crystals of (CuBi8)[AlBr4]2[Al2Br7]. Crystals of [MBi10][AlCl4]4 (M = Pd, Pt) were obtained by reacting Bi, BiCl3, and MCl2 under similar conditions. The structures have been determined by X-ray diffraction on single-crystals and were found to be very similar to that of the known analogues with other halogens, although not isostructural. In crystals of the complex salts, polyhedral bimetallic clusters (CuBi8)3+ or [MBi10]4+ are embedded in matrices of halogenidoaluminate anions. The heteroatomic nido-cluster (CuBi8)3+ consists of a (Bi8)2+ square antiprism η4-coordinating a copper(I) cation. In the cluster cation [MBi10]4+, the metal atoms M center a pentagonal antiprism of bismuth atoms.

Molecular Assembly in Block Copolymer-Surfactant Nanoparticle Dispersions: Information on Molecular Exchange and Apparent Solubility from High-Resolution and PFG NMR

Internally structured block copolymer-surfactant particles are formed when the complex salts of ionic-neutral block copolymers neutralized by surfactant counterions are dispersed in aqueous media. Here, we report the 1H NMR signal intensities and self-diffusion coefficients (D, from pulsed field gradient nuclear magnetic resonance, PFG NMR) of trimethyl alkylammonium surfactant ions and the poly(acrylamide)-block-poly(acrylate) (PAAm-b-PA) polyions forming such particles. The results reveal the presence of an “NMR-invisible” (slowly exchanging) fraction of aggregated surfactant ions in the particle core and an “NMR-visible” fraction consisting of surface surfactant ions in rapid exchange with the surfactant ions dissociated into the aqueous domain. They also confirm that the neutral PAAm blocks are exposed to water at the particle surface, while the PA blocks are buried in the particle core. The self-diffusion of the polyions closely agree with the self-diffusion of a hydrophobic probe molecule solubilized in the particles, showing that essentially all copolymer chains are incorporated in the aggregates. Through centrifugation, we prepared macroscopically phase-separated systems with a phase concentrated in particles separated from a clear dilute phase. D values for the surfactant and block copolymer indicated that the dilute phase contained small aggregates (ca. 5 nm) of surfactant ions and a few anionic-neutral block copolymer chains. Regardless of the overall concentration of the sample, the fraction of block copolymer found in the dilute phase was nearly constant. This indicates that the dilute fraction represented a tail of small particles created by the dispersion process rather than a true thermodynamic solubility of the complex salts.