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Among the positive electrode materials for Na-ion batteries, Na3V2(PO4)2F3 is considered as one of the most promising and generates high interest. Here, we study the influence of the sol–gel synthesis parameters on the structure and on the electrochemical signature of the partially substituted Na3V2−zAlz(PO4)2(F,O)3 materials. We demonstrate that the acidity of the starting solution influences the vanadium oxidation state of the final product. For the first time we report on the possibility of controlling the double Al/V and O/F substitution that leads to the preparation of the Na3V2−zAlz(PO4)2F1+zO2−z solid solution. [ABSTRACT FROM AUTHOR]

Autoprotolysis of the metastable acid (C6F5)3BOPPh2OH, prepared in situ by the reaction of the rather weak Brønsted acid Ph2PO2H with the strong Lewis acid B(C6F5)3, gave rise to the formation of the eight-membered ring [Ph2POB(C6F5)2O]2 and C6F5H. The conjugate base was isolated as stable sodium crown ether salt [Na(15-crown-5)][Ph2PO2B(C6F5)3]. [ABSTRACT FROM AUTHOR]

Three related series of peri-substituted bis(tellurides) bearing naphthalene, acenaphthene and acenaphthylene backbones (Nap/Acenap/Aceyl(TeY)2 (Nap=naphthalene-1,8-diyl N; Acenap=acenaphthene-5,6-diyl A; Aceyl=acenaphthylene-5,6-diyl Ay; Y=Ph 1; Fp 2; Tol 3; An- p­ 4; An- o­ 5; Tp 6; Mes 7; Tip 8) have been synthesised and their solid-state structures determined by X-ray crystallography. Molecular conformations were classified as a function of the two C9-C-Te-C(Y) dihedral angles ( θ); in the solid all members adopt AB or CC t configurations, with larger Te(aryl) moieties exclusively imposing the CC t variant. Exceptionally large J(125Te,125Te) spin-spin coupling constants between 3289-3848 Hz were obtained for compounds substituted by bulky Te(aryl) groups, implying these species are locked in a CC t-type conformation. In contrast, compounds incorporating smaller Te(aryl) moieties are predicted to be rather dynamic in solution and afford much smaller J values (2050-2676 Hz), characteristic of greater populations of AB conformers with lower couplings. This conformational dependence of through-space coupling is supported by DFT calculations. [ABSTRACT FROM AUTHOR]

Four related sterically restricted peri-substitutedacenaphthenes have been prepared containing mixed tin–phosphorusmoieties in the proximal 5,6-positions (Acenap[SnR3][PiPr2]; Acenap = acenaphthene-5,6-diyl;R3= Ph3(1), Ph2Cl(2), Me2Cl (3), Bu2Cl (4)). The degree of intramolecular P–Sn bondingwithin the series was investigated by X-ray crystallography, solutionand solid-state NMR spectroscopy, and density functional theory (DFT/B3LYP/SBKJC/PCM)calculations. All members of the series adopt a conformation suchthat the phosphorus lone pair is located directly opposite the tincenter, promoting an intramolecular donor–acceptor P→Sntype interaction. The extent of covalent bonding between Sn and Pis found to be much greater in triorganotin chlorides 2–4in comparison with the triphenyl derivative 1. Coordination of a highly electronegative chlorine atomnaturally increases the Lewis acidity of the tin center, enhancingthe lp(P)−σ*(Sn–Y) donor–acceptor 3c-4etype interaction, as indicated by conspicuously short Sn–P peridistances and significant 1J(31P,119Sn) spin–spin coupling constants(SSCCs) in the range 740–754 Hz. Evidence supporting the presenceof this interaction was also found in solid-state NMR spectra of someof the compounds which exhibit an indirect spin–spin couplingon the same order of magnitude as observed in solution. DFT calculationsconfirm the increased covalent bonding between P and Sn in 2–4, with notable WBIs of ca. 0.35 obtained, incomparison to 0.1 in 1. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic materials of the type (diamine)MeSO4 (Me = Cd, Zn) [diamine = p-xylylenediamine (PXDA) or m-xylylenediamine (MXDA)] have not been described in the literature to date. Four compounds of this type, namely, (MXDA)ZnSO4 ( 1), (MXDA)CdSO4 ( 2), (PXDA)ZnSO4 ( 3), and (PXDA)CdSO4 ( 4), were synthesized by solvothermal methods. Since all compounds crystallized as very fine powders, crystal structure studies were performed using powder diffraction methods. All compounds crystallize in the orthorhombic crystal system and the cell parameters are: a = 9.8004(4) Å, b = 10.7829(3) Å, c = 4.88473(19) Å for 1; 9.8824(10), 11.0907(7), 4.9663(5) Å for 2; 9.8496(3), 21.2419(5), 4.89556(17) Å for 3; and 10.1136(4), 21.6625(3), 4.9562(2) Å for 4. The compounds with MXDA as a linker, crystallize in the space group P21 ma, those with PXDA in Pnma. These hybrid materials are built of inorganic monolayers [-Me-(SO4)-] joined by organic linkers created by diamines (PXDA or MXDA). Me metal ions and SO42- anions form layers with a honeycomb structure. In addition to crystal structure, chemical analyses and SEM investigations were performed. Thermal stability of the compounds was also investigated using TG-DSC methods and XRD as a function of temperature. [ABSTRACT FROM AUTHOR]

Spin – spin coupling constants (SSCCs) provide valuable information about the environment surrounding coupled atomic nuclei within a molecule and are becoming an increasingly important tool for analysing structures. In their Full Paper on page 3613 ff., J. D. Woollins et al. use X ‐ ray crystallography, NMR spectroscopy and DFT calculations to investigate the conformational dependence of through ‐ space J(125Te,125Te) spin – spin coupling in three related series of peri ‐ substituted bis(tellurides). [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is Cyril Aymonier and co-workers at University of Bordeaux and University of the Basque Country. The image depicts the different distributions of water molecules in xonotlite and tobermorite nanominerals synthesised in supercritical water. Read the full text of the article at 10.1002/chem.202100098., (© 2021 Wiley-VCH GmbH.)

We here present the synthesis of a new material, Na 3 (VO)Fe(PO 4 ) 2 F 2 , by the sol-gel method. Its atomic and electronic structural descriptions are determined by a combination of several diffraction and spectroscopy techniques such as synchrotron X-ray powder diffraction and synchrotron X-ray absorption spectroscopy at V and Fe K edges, 57 Fe Mössbauer, and 31 P solid-state nuclear magnetic resonance spectroscopy. The crystal structure of this newly obtained phase is similar to that of Na 3 (VO) 2 (PO 4 ) 2 F, with a random distribution of Fe 3+ ions over vanadium sites. Even though Fe 3+ and V 4+ ions situate on the same crystallographic position, their local environment can be studied separately using 57 Fe Mössbauer and X-ray absorption spectroscopy at Fe and V K edges, respectively. The Fe 3+ ion resides in a symmetric octahedral environment, while the octahedral site of V 4+ is greatly distorted due to the presence of the vanadyl bond. No electrochemical activity of the Fe 4+ /Fe 3+ redox couple is detected, at least up to 5 V, whereas the reduction of Fe 3+ to Fe 2+ has been observed at ∼1.5 V versus Na + /Na through the insertion of 0.5 Na + into Na 3 (VO)Fe(PO 4 ) 2 F 2 . Comparing to Na 3 (VO) 2 (PO 4 ) 2 F, the electrochemical profile of Na 3 (VO)Fe(PO 4 ) 2 F 2 in the same cycling condition shows a smaller polarization which could be due to a slight improvement in Na + diffusion process thanks to the presence of Fe 3+ in the framework. Furthermore, the desodiation mechanism occurring upon charging is investigated by operando synchrotron X-ray diffraction and operando synchrotron X-ray absorption at V K edge.

Among the positive electrode materials for Na-ion batteries, Na3V2(PO4)2F3 is considered as one of the most promising and generates high interest. Here, we study the influence of the sol-gel synthesis parameters on the structure and on the electrochemical signature of the partially substituted Na3V2-zAlz(PO4)2(F,O)3 materials. We demonstrate that the acidity of the starting solution influences the vanadium oxidation state of the final product. For the first time we report on the possibility of controlling the double Al/V and O/F substitution that leads to the preparation of the Na3V2-zAlz(PO4)2F1+zO2-z solid solution.

Layered oxide compositions Li 3- x Na x Ni 2 SbO 6 have been prepared by solid-state synthesis. A complete solid solution is evidenced and characterized by X-ray and neutron diffraction as well as 7 Li and 23 Na solid-state nuclear magnetic resonance spectroscopy. The transition-metal layer is characterized by the classic honeycomb Ni 2+ /Sb 5+ ordering, whereas a more uncommon randomly mixed occupancy of lithium and sodium is evidenced within the alkali interslab space. In situ X-ray diffraction and density functional theory calculations show that this alkali disordered feature is entropically driven. Fast cooling then appears as a synthesis root to confine bidimensional alkali glass within crystalline layered oxides.

Three related series of peri-substituted bis(tellurides) bearing naphthalene, acenaphthene and acenaphthylene backbones (Nap/Acenap/Aceyl(TeY)2 (Nap = naphthalene-1,8-diyl N; Acenap = acenaphthene-5,6-diyl A; Aceyl = acenaphthylene-5,6-diyl Ay; Y = Ph 1; Fp 2; Tol 3; An-p- 4; An-o- 5; Tp 6; Mes 7; Tip 8) have been synthesised and their solid-state structures determined by X-ray crystallography. Molecular conformations were classified as a function of the two C9-C-Te-C(Y) dihedral angles (θ); in the solid all members adopt AB or CCt configurations, with larger Te(aryl) moieties exclusively imposing the CCt variant. Exceptionally large J((125)Te,(125)Te) spin-spin coupling constants between 3289-3848 Hz were obtained for compounds substituted by bulky Te(aryl) groups, implying these species are locked in a CCt-type conformation. In contrast, compounds incorporating smaller Te(aryl) moieties are predicted to be rather dynamic in solution and afford much smaller J values (2050-2676 Hz), characteristic of greater populations of AB conformers with lower couplings. This conformational dependence of through-space coupling is supported by DFT calculations., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)