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Complexes of the type trans-[Re(PR3)2(Schiff base)]+ (R = ethyl and/or phenyl) 2–7 were prepared by the reaction of (nBu4N)[ReOCl4] with H2sal2en or H2sal2ibn followed by addition of a tertiary phosphine. The trans-[Re(PR3)2(sal2en)]+ complexes 2–4 were stable in solution, whereas the trans-[Re(PR3)2(sal2ibn)]+ complexes 6–7 were observed to convert to their corresponding cis-[ReO(PR3)(sal2ibn)]+ products through a process involving ligand dissociation, metal oxidation, and Schiff base ligand rearrangement. The conversion of the trans-[Re(PR3)2(sal2ibn)]+ complexes is likely driven by steric interactions between the bulky backbone gem-dimethyl groups of the sal2ibn ligand and the phosphine ligands. These complexes were isolated and characterized by 1H and 13C NMR, FT-IR spectroscopy, cyclic voltammetry, and single crystal X-ray diffraction. The results reported herein provide insight into the factors that drive trans-[Re(PR3)2(Schiff base)]+ complex formation. This will aid in the development of novel 186/188Re therapeutic agents and the design of novel bifunctional N2O2 Schiff base ligands. [ABSTRACT FROM AUTHOR]

C15H15N3O2, orthorhombic, Pca21 (no. 29), a = 7.9831(2) Å, b = 10.6486(3) Å, c = 15.7222(4) Å, V = 1336.53(6) Å3, Z = 4, Rgt(F) = 0.0340, wRref(F2) = 0.0799, T = 100 K. [ABSTRACT FROM AUTHOR]

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Abstract The speciation of protic ionic liquids (ILs) has attracted high attention in the recent years, due to its effect in the properties of the resulting liquids. In this work we analyze the behavior of mixtures between triethylamine (N 222) and acetic acid (HOAc), a system that generates controversy about its speciation. Using different synthetic strategies, liquids were obtained with molar compositions that were always between 1:2 and 1:4 mol/mol N 222 :HOAc. However, the experimentally observed normal boiling points indicate that the actual IL has a molar composition of 1:4 N 222 :[HOAc]/[OAc]−. Furthermore, when the synthesized liquid is mixed with the aprotic IL 1‑ethyl‑3‑methylimidazolium acetate, more triethylamine is expelled, indicating that the excess N 222 forms an [HN 222 ]+‑N 222 complex rather than becoming ionized by the remaining HOAc present in the system. Our experimental data emphasizes the consideration of these systems not as mere "mixtures of ions and non-ionized molecules," but as complex systems of oligomeric ions, with distinctive and characteristic properties. Graphical abstract Unlabelled Image Highlights • Mixtures of triethylamine and acetic acid yield non-stoichiometric liquids. • These ionic liquids (ILs) are best described as complex systems of oligomeric ions. • Normal boiling points indicate that the IL has the formula [HN 222 ][OAc]·3[HOAc]. • Excess N 222 forms an [HN 222 ] + ‑N 222 complex rather than becoming ionized. • N 222 /HOAc mixtures show the high complexity at the molecular level of protic ILs. [ABSTRACT FROM AUTHOR]

Two solids of differing Lewis acidities, triethylammonium tetrachlorozincate ([HN222]2[ZnCl4]) and AlCl3, have been combined across 0.1 to 0.9 mole fractions (with respect to [HN222]2[ZnCl4]), and homogeneous solid double salts or mixed metal [HN222]2x[(1 −x)AlCl3 + xZnCl4] double salt ionic liquids (DSILs) were obtained at x = 0.33, 0.4, and 0.5 with varying Lewis acidities. The characterization of the prepared DSILs (melting point, color, homogeneity, 1H, 13C, and 27Al nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), single crystal X-ray diffraction (SCXRD), and matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry) suggests that [HN222]2[ZnCl4] transfers Cl− from [ZnCl4]2− to the stronger Lewis acid AlCl3, forming intermediate acidic DSILs with [AlCl4]− and [Al2Cl7]− anions and mixed anionic Zn species. Qualitative Lewis acidity measurements using acetonitrile as an IR-active probe showed that the acidity of the DSILs decreased as the amount of [ZnCl4]2− increased. In a Beckman rearrangement reaction of acetophenone oxime, significant catalytic activity was observed for the DSIL at x = 0.33, where the activity of the DSIL was found to be even higher than [HN222][Al2Cl7], AlCl3, [HN222]2[ZnCl4], or ZnCl2 despite its lower Lewis acidity, apparently due to the synergistic effect of AlCl3 and [ZnCl4]2− as Cl− donors for the formation of catalytically active species. The findings illustrate a DSIL-based approach for modifying the catalytic activity of a known complex without changing its inner coordination sphere. [ABSTRACT FROM AUTHOR]

We present the first structural report of lanthanides complexed with free amidoxime ligands as part of our ongoing research effort to understand the interactions of amidoximes with metal ions in seawater. Three isomorphous lanthanide complexes with acetamidoxime (AcAO) having the formula Ln2(NO3)6(AcAO)3(OH2)3·3H2O (Ln = Pr3+, Nd3+, Gd3+) have been crystallized and structurally characterised. Notably, the AcAO ligands coordinate in a bridging mode as zwitterions, which creates pre-organised hydrogen bonding cavities into which water molecules are incorporated. Charge-assisted hydrogen bonds to these water molecules appear to stabilize the zwitterionic form and thus the overall complex, underscoring the importance of supramolecular phenomena and overall complex geometry on the relative stability of amidoxime complexes. This has implications for controlling their selectivity towards metal ions. [ABSTRACT FROM AUTHOR]

We present the first structural report of lanthanides complexed with free amidoxime ligands as part of our ongoing research effort to understand the interactions of amidoximes with metal ions in seawater. Three isomorphous lanthanide complexes with acetamidoxime (AcAO) having the formula Ln2(NO3)6(AcAO)3(OH2)3·3H2O (Ln = Pr3+, Nd3+, Gd3+) have been crystallized and structurally characterised. Notably, the AcAO ligands coordinate in a bridging mode as zwitterions, which creates pre-organised hydrogen bonding cavities into which water molecules are incorporated. Charge-assisted hydrogen bonds to these water molecules appear to stabilize the zwitterionic form and thus the overall complex, underscoring the importance of supramolecular phenomena and overall complex geometry on the relative stability of amidoxime complexes. This has implications for controlling their selectivity towards metal ions. [ABSTRACT FROM AUTHOR]

When immersed in 1-methylimidazole, the metals copper, zinc, and cobalt will react with ambient dioxygen and carbon dioxide to yield the blue-green molecular complex Cu(CO3)(MeIm)3 and the pair of isostructural polymeric complexes Zn(CO3)(MeIm)2·2H2O and Co(CO3)(MeIm)2·2H2O, respectively. [ABSTRACT FROM AUTHOR]

6-(3-Methyltriaz-1-en-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione referred to as EG22 (8a), is an open-chain 3-alkyl-1,2,3-triazene termed "combi-molecule" designed to inhibit poly(adenosine diphosphate ribose) polymerase (PARP) and damage DNA. To delay its hydrolysis, acetylation of N3 was required. Being a monoalkyl-1,2,3-triazene, EG22 could assume two tautomers in solution or lose nitrogen during the reaction, thereby leading to several acetylated compounds. Instead, one compound was observed and to unequivocally assign its structure, we introduced isotopically labeled reagents in its preparation, with the purpose of incorporating 15N at N2 and 13C in the 3-methyl group. The results showed that the 1,2,3-triazene moiety remained intact, as confirmed by 15N-NMR, coupling patterns between the 15N-labeled N2 and the 13C-labeled methyl group. Furthermore, we undertook heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments that permitted the detection and assignment of all four nitrogens in 6-(3-acetyl-3-methyltriaz-1-en-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione, referred to as ZSM02 (9a), whose structure was further confirmed by X-ray crystallography. The structure showed a remarkable coplanarity between the N-acetyltriazene and the naphtalimide moiety. Thus, we unequivocally assigned 9a as the product of the reaction and compared its growth inhibitory activity with that of its precursor, EG22. ZSM02 exhibited identical growth inhibitory profile as EG22, suggesting that it may be a prodrug of EG22. [ABSTRACT FROM AUTHOR]