Co(II) Amide, Pyrrolate, and Aminopyridinate Complexes: Assessment of their Manifold Structural Chemistry and Thermal Properties

A series of cobalt(II) (silyl)amides, pyrrolates and aminopyridinates were synthesized. Inspired by the dimeric bis(trimethylsilylamido)cobalt(II) complex ([Co(TMSA)2]2), facile salt metathesis employing the ligand 2,2,5,5-tetramethyl-1,2,5-azadisilolidinyl (TMADS) yielded its congener [Co(TMADS)2]2. Novel, heteroleptic Lewis adducts of the former resulted in unusual three- to four-fold coordination geometry around the metal center. Similarily, the salt [Co(TMADS)3Li(DAD)2] was isolated which demonstrates an ion separated Co(II) anion with silylamide ligation and Li+ counter cation. Transpyrrolylation using [Co(TMSA)2]2 was established for the synthesis of bis[N,N’-2-(dimethylaminomethyl)pyrrolyl]cobalt(II), and bis(N-2-(tert-butyliminomethyl)pyrrolyl)cobalt(II). Treatment of CoCl2 with two equivalents of lithiated N,N-dimethyl(N’-tert-butyl)ethane-1-amino-2-amide and N,N-dimethyl(N’-trimethylsilyl)ethane-1-amino-2-amide resulted in the respective Co(II) amido-amines. Reaction of CoCl2 with lithium 4-methyl-N-(trimethylsilyl)pyridine-2-amide yielded the first binuclear, homoleptic Co(II) aminopyridinate complex with a distorted trigonal bipyramidal coordination environment (τ5 = 0.533) for one central Co(II) ion and a weakly distorted tetrahedral coordination geometry (τ4 = 0.845) for the other. All of the new compounds were thoroughly characterized in terms of composition and structure. Finally, the key thermal characteristics of volatility and thermal stability were assessed using a combination of thermogravimetric analysis and complementary bulk sublimation experiments.

Highly robust, novel aluminum counter cation-based monophosphate tungsten bronze electro-catalysts for oxygen evolution in acidic solution

Highly stable, aluminum counter cation-supported, unusually stabilized W5+-enriched bronzes synthesized for electro-catalytic oxygen evolution in acidic solution.

A series of counter cation dependent tetra β-diketonate mononuclear lanthanide(III) single-molecule magnets and immobilization on pre-functionalised GaN substrates by anion exchange reaction

A series of mononuclear lanthanide complexes with formula [Hex4N][Ln(DBM)4] (1Ln) (Ln = Nd and Tb), [But4N][Dy(DBM)4] (2), [Et4N][Dy(DBM)4] (3), [PhCH2N(CH3)3][Dy(DBM)4] (4) and [Hex4N][Dy(TTA)4 (5) formed by four β-diketonate ligands (i.e....

Crystal structure and photophysical properties of a novel polyoxomolybdate porphyrin

A novel polyoxomolybdate with a diprotonated porphyrin as counter-cation, namely, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,22H,23H,24H-porphine(2+) hexamolybdate(VI) pentahydrate, (C48H32N4O8)[Mo6O19]·5H2O or (H2TCPP)[Mo6O19]·5H2O, I, was prepared via the hydrothermal reaction of MoCl5, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,23H-porphine (TCPP) and distilled water. The crystal structure of hydrated polyoxometalate (POM) salt I was characterized by single-crystal X-ray diffraction. The compound is characterized by an isolated (zero-dimensional, 0D) structure, because it cannot extend via covalent bonds. The structure contains one [Mo6O19]2− anion, one (H2TCPP)2+ cation and five lattice water molecules. Each of the Mo6+ ions is six-coordinated and displays a distorted octahedral motif. The (H2TCPP)2+ cation displays a distorted saddle motif. A three-dimensional (3D) supramolecular framework is formed via hydrogen-bonding interactions. The compound shows a red photoluminescence emission.

Synthesis and Characterization of Ion Pairs between Alkaline Metal Ions and Anionic Anti-Aromatic and Aromatic Hydrocarbons with π-Conjugated Central Seven- and Eight-Membered Rings

The synthesis, isolation and full characterization of ion pairs between alkaline metal ions (Li+, Na+, K+) and mono-anions and dianions obtained from 5H-dibenzo[a,d]cycloheptenyl (C15H11 = trop) is reported. According to Nuclear Magnetic Resonance (NMR) spectroscopy, single crystal X-ray analysis and Density Functional Theory (DFT) calculations, the trop‒ and trop2−• anions show anti-aromatic properties which are dependent on the counter cation M+ and solvent molecules serving as co-ligands. For comparison, the disodium and dipotassium salt of the dianion of dibenzo[a,e]cyclooctatetraene (C16H12 = dbcot) were prepared, which show classical aromatic character. A d8-Rh(I) complex of trop− was prepared and the structure shows a distortion of the C15H11 ligand into a conjugated 10π -benzo pentadienide unit—to which the Rh(I) center is coordinated—and an aromatic 6π electron benzo group which is non-coordinated. Electron transfer reactions between neutral and anionic trop and dbcot species show that the anti-aromatic compounds obtained from trop are significantly stronger reductants.

TRACE LEVEL DETERMINATION OF SODIUM CHLORIDE AND SODIUM SULFATE CONTENT IN SODIUM LAURETH SULFATE RAW MATERIAL USING COUNTER CATION-EXCHANGE HPLC WITH INDIRECT ULTRAVIOLET DETECTION

Objective: A novel study on a new liquid chromatographic approach has been developed and validated for simultaneous determination of trace level determination of sodium chloride and sodium sulfate measures its impurities using counter cation-exchange high-performance liquid chromatography with indirect ultraviolet (UV) detection. Methods: Chromatographic separation is developed and validated on a Hamilton PRP-X100 column with a mobile phase contained a mixture of the para-hydroxybenzoic acid buffer with a pH of 9.0 and methanol. Chromatography is developed at a flow rate of 2.0 mL/min with an indirect UV determination at 310 nm at a sensitivity level of 0.5%. The optimized method was validated as per the ICH Q2 guidelines. Results: The retention times of chloride and sulfate were about 2.8 and 7.6 min, respectively. The resolution between chloride and sulfate peaks is >4. Regression analysis confers a correlation coefficient for the stated compounds that are found to be >0.999. Conclusion: A novel analytical method was validated as per the ICH method validation guidelines and found to be selective. Hence, the validated analytical method was precise, specific, and accurate, and it is more economic and simple for the determination of inorganic impurities.