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The structure of a second polymorph of CaSiF6·2H2O [calcium hexafluorido­silicate dihydrate; space group P2/c (No. 13), Pearson symbol mP2] was elucidated by single-crystal X-ray diffraction. It arose as an unexpected product when soda-lime glass was attacked by HF. Its crystal structure consists of infinite ∞²[Ca(H2O)2/1(SiF6)4/4] layers oriented parallel to the bc-crystallographic plane, a unique motif among structurally characterized hydrated hexa­fluorido­silicates. The crystal structure also exhibits inter- and intra­layer hydrogen bonds, with the inter­layer O—HO hydrogen bonds involving a disordered hydrogen atom. The large deviation between the calculated bond-valence sum for Si and the expected value prompted a redetermination of the empirical SiIV–F bond-valence parameter R0. Based on a data set of 42 high-quality crystal structures containing 49 independent SiIV coordination environments, a revised value of 1.534 Å was derived for R0. [ABSTRACT FROM AUTHOR]

The structure of a second polymorph of CaSiF6·2H2O [calcium hexafluorido­silicate dihydrate; space group P2/c (No. 13), Pearson symbol mP2] was elucidated by single-crystal X-ray diffraction. It arose as an unexpected product when soda-lime glass was attacked by HF. Its crystal structure consists of infinite ∞²[Ca(H2O)2/1(SiF6)4/4] layers oriented parallel to the bc-crystallographic plane, a unique motif among structurally characterized hydrated hexa­fluorido­silicates. The crystal structure also exhibits inter- and intra­layer hydrogen bonds, with the inter­layer O—HO hydrogen bonds involving a disordered hydrogen atom. The large deviation between the calculated bond-valence sum for Si and the expected value prompted a redetermination of the empirical SiIV–F bond-valence parameter R0. Based on a data set of 42 high-quality crystal structures containing 49 independent SiIV coordination environments, a revised value of 1.534 Å was derived for R0. [ABSTRACT FROM AUTHOR]

Hydrogen-bonded cocrystals have attracted considerable attention as they allow fine-tuning of properties through the choice of hydrogen-bond donors and acceptors. In this study, triphenylarsine oxide (Ph 3 AsO) is introduced as a strong hydrogen-bond acceptor molecule. Due to its higher Lewis basicity compared to triphenylphosphine oxide (Ph 3 PO), it acts as a strong hydrogen-bond acceptor, which is demonstrated in six new cocrystals with H 2 O 2 and gem -di(hydroperoxy)cycloalkanes. All cocrystals formed large, high-quality single crystals, which were analyzed by X-ray diffraction and IR spectroscopy. The cocrystal of Ph 3 AsO with H 2 O 2 shows prolonged stability without loss of oxidative power. In addition, the newly formed interactions were also present in solution and were detected by NMR spectroscopy. The higher electron-donating ability of Ph 3 AsO compared to Ph 3 PO was confirmed by competition experiments. Ph 3 AsO exclusively binds H 2 O 2 , even in dilute aqueous solutions and in the presence of Ph 3 PO. This study expands the range of hydrogen-bond acceptors and demonstrates that Ph 3 AsO is a useful cocrystallizing tool in crystal engineering and a sensitive marker for hydrogen peroxide.

Fluoridoargentates(II) represent a fascinating class of silver(II) compounds with structural and magnetic similarities to cuprate superconductors. However, their synthesis is challenging, leaving their properties largely underexplored and hindering the discovery of new phases. This study introduces mechanochemistry as a novel approach for the synthesis of fluoridoargentates(II), avoiding the use of anhydrous HF or elemental fluorine and employing readily available equipment. Notably, ball milling of commercially available precursors successfully produced the long-sought-after first two examples of binary mixed-valent silver(I,II) phases, Ag I 2 Ag II F 4 (Ag 3 F 4 ) and Ag I Ag II F 3 (Ag 2 F 3 ). While the Ag I 2 Ag II F 4 phase was obtained at room temperature, the Ag I Ag II F 3 phase is metastable and required milling under cryogenic conditions. Characterization by synchrotron powder X-ray and neutron diffraction revealed that Ag I 2 Ag II F 4 crystallizes in the P 2 1 / c space group and is isostructural to β-K 2 AgF 4 . In this crystal structure, [Ag II F 2 F 4/2 ] 2- distorted octahedral units with 4 + 2 coordination, extend parallel to a -crystallographic axis giving a quasi-one-dimensional canted antiferromagnetic character, as shown by magnetic susceptibility. The triclinic perovskite Ag I Ag II F 3 phase adopts the P 1̅ space group, is isostructural to AgCuF 3 and also shows features of a one-dimensional antiferromagnet. This mechanochemical approach, also successfully applied to synthesize β-K 2 AgF 4 , is expected to expand the field of silver(II) chemistry, accelerating the search for silver analogs to cuprate superconductors and potentially extending to other cations in unusual oxidation states.

Recent advances in 3D electron diffraction (3D ED) have succeeded in matching the capabilities of single-crystal X-ray diffraction (SCXRD), while requiring only submicron crystals for successful structural investigations. One of the many diverse areas to benefit from the 3D ED structural analysis is main-group chemistry, where compounds are often poorly crystalline or single-crystal growth is challenging. A facile method for loading and transferring highly air-sensitive and strongly oxidizing samples at low temperatures to a transmission electron microscope (TEM) for 3D ED analysis was successfully developed and tested on xenon(II) compounds from the XeF 2 -MnF 4 system. The crystal structures determined on nanometer-sized crystallites by dynamical refinement of the 3D ED data are in complete agreement with the results obtained by SCXRD on micrometer-sized crystals and by periodic density-functional theory (DFT) calculations, demonstrating the applicability of this approach for structural studies of noble-gas compounds and highly reactive species in general. The compounds 3XeF 2 ·2MnF 4 , XeF 2 ·MnF 4 , and XeF 2 ·2MnF 4 are rare examples of structurally fully characterized xenon difluoride-metal tetrafluoride adducts and thus advance our knowledge of the diverse structural chemistry of these systems, which also includes the hitherto poorly characterized first noble-gas compound, "XePtF 6 "., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The dimer of the tetracyanoethylene (TCNE) radical anions represents the simplest and the best studied case of two-electron multicenter covalent bonding (2e/mc or pancake bonding ). The model compound, N -methylpyridinium salt of TCNE •- , is diamagnetic, meaning that the electrons in two contiguous radicals are paired and occupy a HOMO orbital which spans two TCNE •- radicals. Charge density in this system is studied as a benchmark for comparison of charge densities in other pancake-bonded radical systems. Two electrons from two contiguous radicals indeed form a bonding electron pair, which is distributed between two central ethylene groups in the dimer, i.e., between four carbon atoms. The topology of electron density reveals two bond critical points between the central ethylene groups in the dimer, with maximum electron density of 0.185 e Å -3 ; the corresponding theoretical value is 0.118 e Å -3 ., Competing Interests: The authors declare no competing financial interest., (© 2024 American Chemical Society.)

Fluorescent probes are a powerful tool for imaging amyloid β (Aβ) plaques, the hallmark of Alzheimer's disease (AD). Herein, we report the synthesis and comprehensive characterization of 21 novel probes as well as their optical properties and binding affinities to Aβ fibrils. One of these dyes, 1Ae, exhibited several improvements over FDDNP, an established biomarker for Aβ- and Tau-aggregates. First, 1Ae had large Stokes shifts (138-213 nm) in various solvents, thereby reducing self-absorption. With a high quantum yield ratio (φ(dichloromethane/methanol) = 104), 1Ae also ensures minimal background emission in aqueous environments and high sensitivity. In addition, compound 1Ae exhibited low micromolar binding affinity to Aβ fibrils in vitro (K d = 1.603 µM), while increasing fluorescence emission (106-fold) compared to emission in buffer alone. Importantly, the selective binding of 1Ae to Aβ 1-42 fibrils was confirmed by an in cellulo assay, supported by ex vivo fluorescence microscopy of 1Ae on postmortem AD brain sections, allowing unequivocal identification of Aβ plaques. The intermolecular interactions of fluorophores with Aβ were elucidated by docking studies and molecular dynamics simulations. Density functional theory calculations revealed the unique photophysics of these rod-shaped fluorophores, with a twisted intramolecular charge transfer (TICT) excited state. These results provide valuable insights into the future application of such probes as potential diagnostic tools for AD in vitro and ex vivo such as determination of Aβ 1-42 in cerebrospinal fluid or blood., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

We have developed an efficient and versatile approach for the synthesis of a family of 1,2,3-triazole-based mesoionic N-heterocyclic olefin (mNHO) ligands and investigated their coordination to palladium, gold, and boron hydride experimentally and computationally. We reacted mNHOs obtained through deprotonation of the corresponding methylated and ethylated 1,3,4-triaryl-1,2,3-triazolium salts with [Pd(allyl)Cl] 2 to give the corresponding [Pd(η 3 -allyl)Cl(mNHO)] coordination complexes. 13 C NMR data revealed the strong σ-donor character of the mNHO ligands, consistent with the calculated bond orders and atom-condensed charges. Furthermore, we also synthesized [AuCl(mNHO)] and a BH 3 -mNHO adduct by reacting the triazolium salts with AuCl(SMe 2 ) and BH 3 ·THF, respectively. The BH 3 -mNHO adduct was tested in the reduction of select aldehydes and ketones to alcohols.

The crystal structure of 3-nitrobenzonitrile, C 7 H 4 N 2 O 2 , was elucidated by low-temperature single-crystal X-ray diffraction. The compound crystallizes in the Sohncke space group P 2 1 and features two mol-ecules in the unit cell. Aromatic π-π stacking leads to stacks of mol-ecules in the [100] direction. The absolute structure was established from anomalous dispersion., (© Virant et al. 2023.)

Partial hydrolysis of a sample of [Mg(dme) 3 ][Al(hfip) 4 ] 2 crystals led to the formation of the title complex, [Mg(dme) 2 {HOAl(hfip) 2 OAl(hfip) 3 }] (dme = di-meth-oxy-ethane and hfipH = hexa-fluoro-iso-propanol) or [Mg(C 4 H 10 O 2 ) 2 O(OH)Al 2 (C 3 HF 6 O) 5 ]. The magnesium cation exhibits a distorted octa-hedral coordination with two bidentate di-meth-oxy-ethane mol-ecules and a dinuclear aluminate anion, coordinated to Mg 2+ via oxido and hydroxido units. The anion is an oxido-bridged species, [HOAl(hfip) 2 (μ-O)Al(hfip) 3 ] 2- , with one Al 3+ cation tetra-hedrally coordinated by an oxido (O 2- ) anion, a hydroxido anion, and two hfip groups, whereas the second Al 3+ cation is coordinated by the oxido anion and three hfip groups., (© Lozinšek et al. 2023.)

Stereopure CF 3 -substituted syn -1,2-diols were prepared via the reductive dynamic kinetic resolution of the corresponding racemic α-hydroxyketones in HCO 2 H/Et 3 N. (Het)aryl, benzyl, vinyl, and alkyl ketones are tolerated, delivering products with ≥95% ee and ≥87:13 syn / anti . This methodology offers rapid access to stereopure bioactive molecules. Furthermore, DFT calculations for three types of Noyori-Ikariya ruthenium catalysts were performed to show their general ability of directing stereoselectivity via the hydrogen bond acceptor SO 2 region and CH/π interactions., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The title hydrate, Me 3 PO·2H 2 O, crystallizes in the ortho-rhom-bic space group Pbca with eight formula units per unit cell. The extended structure displays O-H⋯O hydrogen bonding, with Me 3 PO mol-ecules as acceptors and water mol-ecules acting as donors and acceptors of hydrogen bonds, forming hydrogen-bonded layers, which propagate in the ac plane., (© Urlep et al. 2023.)

The crystal structure of the title enanti-opure tetralol derivative {systematic name: (1 S ,2 S )-2-[( S )-2,2,2-tri-fluoro-1-hy-droxy-eth-yl]-1,2,3,4-tetra-hydro-naph-thalen-1-ol}, C 12 H 13 F 3 O 2 , synthesized by asymmetric transfer hydrogenation, was elucidated by low-temperature single-crystal X-ray diffraction. The enanti-opure compound crystallizes in the Sohncke space group P 2 1 2 1 2 1 with one mol-ecule in the asymmetric unit and features intra-molecular as well as inter-molecular O-H⋯O hydrogen bonding. The absolute configuration was established from anomalous dispersion effects., (© Radan et al. 2023.)

The crystal structure of the co-crystal of aqua-tri-fluorido-boron with two ethyl-ene carbonate (systematic name: 1,3-dioxolan-2-one) mol-ecules, BF 3 H 2 O·2OC(OCH 2 ) 2 , was determined by low-temperature single-crystal X-ray diffraction. The co-crystal crystallizes in the ortho-rhom-bic space group P 2 1 2 1 2 1 with four formula units per unit cell. The asymmetric unit consists of an aqua-tri-fluorido-boron mol-ecule and two ethyl-ene carbonate mol-ecules, connected by O-H⋯O=C hydrogen bonds. This crystal structure is an inter-esting example of a superacidic BF 3 H 2 O species co-crystallized with an organic carbonate., (© Radan et al. 2023.)

A crystal structure reinvestigation of AgF based on a low-temperature high-resolution single-crystal X-ray diffraction data is reported. Silver(I) fluoride crystallizes in the rock salt structure type ( Fm m ) with a unit-cell parameter of 4.92171 (14) Å at 100 K, resulting in an Ag-F bond length of 2.46085 (7) Å., (© Lozinšek et al. 2023.)

The crystal structure of the title compound, C 12 H 11 F 3 O 2 , was elucidated by low-temperature single-crystal X-ray diffraction. The enanti-opure compound crystallizes in the Sohncke space group P 2 1 and features one mol-ecule in the asymmetric unit. The structure displays inter-molecular O-H⋯O hydrogen bonding, which links the mol-ecules into infinite chains propagating parallel to [010]. The absolute configuration was established from anomalous dispersion., (© Motaln et al. 2023.)

We describe an efficient catalytic strategy for enantio- and diastereoselective synthesis of homochiral β-CF 3 , β-SCF 3 , and β-OCF 3 benzylic alcohols. The approach is based on dynamic kinetic resolution (DKR) with Noyori-Ikariya asymmetric transfer hydrogenation leading to simultaneous construction of two contiguous stereogenic centers with up to 99.9% ee, up to 99.9:0.1 dr, and up to 99% isolated yield. The origin of the stereoselectivity and racemization mechanism of DKR is rationalized by density functional theory calculations. Applicability of the previously inaccessible chiral fluorinated alcohols obtained by this method in two directions is further demonstrated: As building blocks for pharmaceuticals, illustrated by the synthesis of heat shock protein 90 inhibitor with in vitro anticancer activity, and in particular, needle-shaped crystals of representative stereopure products that exhibit either elastic or plastic flexibility, which opens the door to functional materials based on mechanically responsive chiral molecular crystals., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

High-performance electrolytes are at the heart of magnesium battery development. Long-term stability along with the low potential difference between plating and stripping processes are needed to consider them for next-generation battery devices. Within this work, we perform an in-depth characterization of the novel Mg[Al(hfip) 4 ] 2 salt in different glyme-based electrolytes. Specific importance is given to the influence of water content and the role of additives in the electrolyte. Mg[Al(hfip) 4 ] 2 -based electrolytes exemplify high tolerance to water presence and the beneficial effect of additives under aggravated cycling conditions. Finally, electrolyte compatibility is tested with three different types of Mg cathodes, spanning different types of electrochemical mechanisms (Chevrel phase, organic cathode, sulfur). Benchmarking with an electrolyte containing a state-of-the-art Mg[B(hfip) 4 ] 2 salt exemplifies an improved performance of electrolytes comprising the Mg[Al(hfip) 4 ] 2 salt and establishes Mg[Al(hfip) 4 ] 2 as a new standard salt for the future Mg battery research.

The crystal structure of oxido-nitro-gen(1+) tetra-fluorido-borate (nitro-sonium tetra-fluorido-borate), NO + BF 4 - , was refined on the basis of single-crystal X-ray diffraction data at 150 K. The compound crystallizes in the baryte structure type with ortho-rhom-bic Pnma symmetry. The crystal structure exhibits cationic disorder with equal occupation of N and O atoms at the same site., (© Matic Lozinšek 2021.)

The coordination chemistry of KrF 2 has been limited in contrast with that of XeF 2 , which exhibits a far richer coordination chemistry with main-group and transition-metal cations. In the present work, reactions of [XeF 5 ][AsF 6 ] with KrF 2 in anhydrous HF solvent afforded [F 5 Xe(FKrF)AsF 6 ] and [F 5 Xe(FKrF) 2 AsF 6 ], the first mixed krypton/xenon compounds. X-ray crystal structures and Raman spectra show the KrF 2 ligands and [AsF 6 ] - anions are F-coordinated to the xenon atoms of the [XeF 5 ] + cations. Quantum-chemical calculations are consistent with essentially noncovalent ligand-xenon bonds that may be described in terms of σ-hole bonding. These complexes significantly extend the XeF 2 -KrF 2 analogy and the limited chemistry of krypton by introducing a new class of coordination compound in which KrF 2 functions as a ligand that coordinates to xenon(VI). The HF solvates, [F 5 Xe(FH)AsF 6 ] and [F 5 Xe(FH)SbF 6 ], are also characterized in this study and they provide rare examples of HF coordinated to xenon(VI)., (© 2020 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A highly efficient enantio- and diastereoselective catalyzed asymmetric transfer hydrogenation via dynamic kinetic resolution (DKR-ATH) of α,β-dehydro-α-acetamido and α-acetamido benzocyclic ketones to ent- trans-β-amido alcohols is disclosed employing a new ansa-Ru(II) complex of an enantiomerically pure syn- N, N-ligand, i.e. ent- syn-ULTAM-(CH 2 ) 3 Ph. DFT calculations of the transition state structures revealed an atypical two-pronged substrate attractive stabilization engaging the commonly encountered CH/π electrostatic interaction and a new additional O═S═O···HNAc H-bond hence favoring the trans-configured products.

Eight M(H 2 O) n (Z) salt hydrates were characterized by single-crystal X-ray diffraction (Z 2- = B 12 F 12 ): M = Ca, Sr, n = 7; M = Mg, Co, Ni, Zn, n = 6; M = Ba, n = 4, 5. Weak O-H···F hydrogen bonding between the M(H 2- ): M = Ca, Sr, n = 7; M = Mg, Co, Ni, Zn, n = 6; M = Ba, n = 4, 5. Weak O-H···F hydrogen bonding between the M(H 2 O) n 2+ cations and Z 2- resulted in room-temperature Fourier transform infrared (FTIR) spectra having sharp ν(OH) bands, with full widths at half max of 10-30 cm -1 , which are much more narrow than ν(OH) bands in room temperature FTIR spectra of most salt hydrates. Clearly resolved ν asym (OH/OD) and ν sym (OH/OD) bands with Δν(OH) as small as 17 cm -1 and Δν(OD) as small as 11 cm -1 were observed (Δν(OX) = ν asym (OX) - ν sym (OX)). The isomorphic hexahydrates ( R3̅) have two fac-(H 2 O) 3 sets of H 2 O ligands and nearly octahedral coordination spheres. They exhibited four resolvable ν(OH) bands, one ν asym (OH)/ν sym (OH) pair for H 2 O ligands with longer O(H)···F distances and one ν asym (OH)/ν sym (OH) pair for H 2 O ligands with shorter O(H)···F distances. The ν(OH) bands for the three H 2 O molecules with shorter, slightly stronger O(H)···F hydrogen bonds were broader, more intense, and red-shifted by ca. 25 cm -1 relative to the bands for the three other H 2 O molecules, the first time that such small differences in relatively weak O(H)···F hydrogen bonds in the same crystalline hexahydrate have resulted in observable IR spectroscopic differences at room temperature. For the first time room temperature ν(OH) values for salt hexahydrates showed the monotonic progression Mg 2+ > Co 2+ > Ni 2+ > Zn 2+ , essentially the same progression as the p K a values for these metal ions in aqueous solution. A further manifestation of the weak O-H···F hydrogen bonding in these hydrates is the latent porosity exhibited by Ba(H 2 O) 5,8 (Z), Sr(H 2 O) n,m (Z), and Ca(H 2 O) 4,6 (Z). Finally, the H 2 O/D 2 O exchange reaction Co(D 2 O) 6 (Z) → Co(H 2 O) 6 (Z) was ca. 50% complete in 1 h at 50 °C in N 2 /17 Torr H 2 O( g).

Metallic lithium is considered to be one of the most promising anode materials since it offers high volumetric and gravimetric energy densities when combined with high-voltage or high-capacity cathodes. However, the main impediment to the practical applications of metallic lithium is its unstable solid electrolyte interface (SEI), which results in constant lithium consumption for the formation of fresh SEI, together with lithium dendritic growth during electrochemical cycling. Here we present the electrochemical performance of a fluorinated reduced graphene oxide interlayer (FGI) on the metallic lithium surface, tested in lithium symmetrical cells and in combination with two different cathode materials. The FGI on the metallic lithium exhibit two roles, firstly it acts as a Li-ion conductive layer and electronic insulator and secondly, it effectively suppresses the formation of high surface area lithium (HSAL). An enhanced electrochemical performance of the full cell battery system with two different types of cathodes was shown in the carbonate or in the ether based electrolytes. The presented results indicate a potential application in future secondary Li-metal batteries.

Structures of the alkali-metal hydrates Li 2 (H 2 O) 4 Z, LiK(H 2 O) 4 Z, Na 2 (H 2 O) 3 Z, and Rb 2 (H 2 O) 2 Z, unit cell parameters for Rb 2 Z and Rb 2 (H 2 O) 2 Z, and the density functional theory (DFT)-optimized structures of K 2 Z, K 2 (H 2 O) 2 Z, Rb 2 Z, Rb 2 (H 2 O) 2 Z, Cs 2 Z, and Cs 2 (H 2 O)Z are reported (Z 2- = B 12 F 12 2- ) and compared with previously reported X-ray structures of Na 2 (H 2 O) 0,4 Z, K 2 (H 2 O) 0,2,4 Z, and Cs 2 O)Z. Unusually rapid room-temperature hydration/dehydration cycles of several M 2 Z/M 2 Z/M 2 (H 2 O) n Z salt hydrate pairs, which were studied by isothermal gravimetry, are also reported. Finely ground samples of K 2 Z, Rb 2 Z, and Cs 2 Z, which are not microporous, exhibited latent porosity by undergoing hydration at 24-25 °C in the presence of 18 Torr of H 2 O(g) to K 2 (H 2 O) 2 Z, Rb 2 (H 2 O) 2 Z, and Cs 2 (H 2 to the original anhydrous M 2 to the original anhydrous M 2 Z compounds in 61, 25, and 76 min, respectively (the exact times varied from sample to sample depending on the particle size). The hydrate Na 2 (H 2 O) 2 Z also exhibited latent porosity by undergoing multiple 90 min cycles of hydration to Na 2 (H 2 O) 3 Z and dehydration back to Na 2 (H 2 O) 2 Z at 23 °C. For the K 2 Z, Rb 2 Z, and Cs 2 Z transformations, the maximum rate of hydration (rh max ) decreased, and the absolute value of the maximum rate of dehydration (rd max ) increased, as T increased. For K 2 Z ↔ K 2 (H 2 O) 2 Z hydration/dehydration cycles with the same sample, the ratio rh max /rd max decreased 26 times over 8.6 °C, from 3.7 at 23.4 °C to 0.14 at 32.0 °C. For Rb 2 Z ↔ Rb 2 (H 2 O) 2 Z cycles, rh max /rd max decreased from 0.88 at 23 °C to 0.23 at 27 °C. For Cs 2 Z ↔ Cs 2 (H 2 O)Z cycles, rh max /rd max decreased 20 times over 8 °C, from 6.7 at 24 °C to 0.34 at 32 °C. In addition, the reversible substitution of D 2 O for H 2 O in fully hydrated Rb 2 (H 2 O) 2 Z in the presence of N 2 /16 Torr of D 2 O(g) was complete in only 60 min at 23 °C.

Examples of coordination compounds in which KrF 2 functions as a ligand are very rare. In contrast, XeF 2 provides a rich coordination chemistry with a variety of main-group and transition metal cations. The reactions of Mg(AsF 6 ) 2 and KrF 2 in HF or BrF 5 solvent have afforded [Mg(KrF 2 ) 4 (AsF 6 ) 2 ] and [Mg(KrF 2 ) 4 (AsF 6 ) 2 ]⋅2 BrF 5 , respectively, the first examples of a metal cation ligated by KrF 2 . Their X-ray crystal structures and Raman spectra show that the KrF 2 ligands and [AsF 6 ] - anions are F-coordinated to a naked Mg 2+ cation. Quantum-chemical calculations are consistent with essentially non-covalent ligand-metal bonding. These compounds significantly extend the XeF 2 -KrF 2 analogy and the limited chemistry of krypton by introducing a new class of coordination compound in which KrF 2 functions as a ligand towards a naked metal cation., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hydroxylammonium tetrafluoridooxidovanadate(V) has been prepared by reaction of (NH3OH)Cl and VOF3 in anhydrous HF solvent and characterised in the solid state by single-crystal X-ray diffraction and Raman spectroscopy. Colourless (NH3OH)[VOF4] crystallises in the monoclinic P21/n space group with a = 7.2349(2) Å, b = 5.0351(2) Å, c = 12.8322(4) Å, β = 94.843(3)°, V = 465.79(3) Å3 and Z = 4 at 150 K. The crystal structure of the title compound is comprised of polymeric chain anions, [VOF4]nn-, interconnected by hydrogen bonds with hydroxylammonium cations, (NH3OH)+.

Silver(I) tetrafluoridooxidovanadate(V) which contains the polymeric chain anion, [VOF(4)](nn-), has been prepared in reaction between AgNO(3) and VOF(3) in anhydrous HF solvent and characterised in the solid state by single-crystal X-ray diffraction and Raman spectroscopy. Pale yellow crystals of Ag[VOF(4)] crystallise in a monoclinic P2(1)/c space group with a = 5.5452(4) Å, b = 5.0071(3) Å, c = 13.6511(11) Å, beta = 100.543(3)°, and V = 372.63(5) Å(3) at 200 K with Z = 4. The most intense feature in the Raman spectrum is the V=O stretching band of the anion at 1008 cm-1. Solid-state conformational isomerism exists between [VOF(4)](-) anions in crystal structures of Ag[VOF(4)] and previously reported and structurally characterised K[VOF(4)] and Cs[VOF(4)] salts.