X-ray Structure Determination Research Articles

A novel layered structure of the heterometallic oxalate compound [NH2(CH3)2]2[NaFe(C2O4)3]·0.33NH(CH3)2·0.33H2O: synthesis, crystal structure and thermal decomposition.

The synthesis, single-crystal X-ray structure determination and thermal analysis are reported for a novel heteronuclear oxalate compound synthesized from a mixture of Fe and Na salts, oxalic acid and N,N-dimethylformamide (DMF) in aqueous solution. The new metallooxalate compound was obtained and identified as a dimethylammonium tris(oxalato)ferrate(III), namely, poly[[bis(dimethylammonium) [tri-μ-oxalato-sodium(I)iron(III)]]-dimethylamine-water (3/1/1)], [NH2(CH3)2]2[NaFe(C2O4)3]·0.33NH(CH3)2·0.33H2O, which crystallizes in the orthorhombic noncentrosymmetric space group C2221. In this novel structure, each Fe atom is hexacoordinated by three non-equivalent bidentate oxalate ligands, while the four Na atoms adopt different coordination numbers, i.e. 6, 7 and 8. The structure consists of bimetallic anionic A layers, {[NaFe(C2O4)3]2-}n, displaying a layered structure with infinitely linked Fe2Na2 tetramers on the ab plane. Two kinds of bimetallic parallel layers (A1 and A2) are present alternately and are found to be staggered, while only the A2 layer is crossed by a twofold axis parallel to the a axis through two Na atoms. The [NH2(CH3)2]+ (HDMA) cations occupy the voids between the anionic layers, while the free molecules, i.e. NH(CH3)2 (DMA) and H2O, are located between two different anionic layers. In addition to ionic bonds, the stability of the structure is ensured by hydrogen-bond interactions involving the oxalate ligands and the nitrogenous and water molecules. The layered structure appears to be different in the family of oxalate-bridged NaI-FeIII compounds. It is in agreement with the predicted 2D or layered structure of bimetallic complexes containing anionic tris(oxalato)metallate(III) with the [XR4]+ counter-ion template (X= N, P or S, and R= alkyl group or H). The thermal decomposition of the compound shows the final residual product to be NaFeO2.

Redox Noninnocent Copper(I) Complex Where Metal Is a Spectator and Ligand Is an Actor in the Glaser Coupling Reaction of Alkynes.

An extended trisazo dipyridyl ligand, L, and its copper(I) complex, [1]+, were synthesized and fully characterized. Complex [1]+ has five coordination geometry satisfied by ligand L. L has a low-lying π* orbital; thus, [1]+ showed very facile multiple ligand-based redox events. Moreover, due to the strong π-acceptor nature of L, the Cu(II)/Cu(I) redox potential of [1]+ was anodic (0.62 V). The redox events of both L and [1]+ were characterized using various spectroscopic studies and density functional theory (DFT) calculations. Taking advantage of the multiple facile ligand-based reductions in [1]+, the Glaser coupling reaction of terminal alkynes was explored. Various kinds of alkynes were found to be effective when using [1]+ as a precatalyst. The mechanism of the reaction was investigated thoroughly by several controlled experiments, isolation, and characterization of the intermediates using various spectroscopic studies as well as by single-crystal X-ray structure determination. These studies showed that the L in [1]+ acted not only in the electron transfer events but also as a locus for binding the substrate, breaking and forming bonds, and, finally, releasing the product. Thus, here, the metal mainly acted as a spectator and ligand L acted as an actor.

Cold and Liquid Crystal Properties of Square-Planar Copper(II) Versus Nickel(II)- Iminophenolate/Naphthalen-2-Olate Schiff Base Complexes.

Reaction of the phenolate or naphthalen-2-olate based Schiff base ligands, (E)-1-((2-ethylphenylimino)methyl)phenol (HL1) or (E)-1-((2-ethylphenylimino)methyl)naphthalen-2-ol (HL2) with nickel(II) and copper(II) acetate provides the complexes bis[(E)-1-((2-ethylphenylimino)methyl)phenolato-ĸ2N,O]Ni/Cu(II), [Ni(L1)2] (1) and [Cu(L1)2] (2), or bis[(E)-1-((2-ethylphenylimino)methyl)naphthalen-2-olato-ĸ2N,O]Ni/Cu(II), [Ni(L2)2] (3) and [Cu(L2)2] (4), respectively. Single crystal X-ray structure determinations for 1, 3 and 4 reveal N2,O2-metal coordination of two chelating Schiff base ligands in a square-planar geometry. Powder X-ray diffractograms confirm the phase purity of the bulk microcrystalline samples. Thermal analyses by differential scanning calorimetry (DSC) and polarized light microscopic (PLM) indicate the copper(II) complexes to exhibit cold crystal (2) and liquid crystal (4) property. Cyclic voltammograms suggest an irreversible electrochemical process with two one electron charge transfer processes in N,N-dimethylformamide. Variable temperature magnetic measurements at the solid-state prove the diamagnetic nature of the low-spin Ni2+ centres in 1 or 3, as expected from the square-planar coordination geometry with rather strong ligands. The complexes expose medium level of antioxidant activity in methanol. Optimized geometry and excited state property by DFT/TD-DFT correspond well to the experimental results of the electronic and molecular structure at the ground state.

Novel Crystalline Salts of 4-Piperidyl- and 4-Pyridylmethylamines Prepared by Catalytic Hydrogenation of 4-Pyridinecarbonitrile: Crystallographic Unit Cells Based on Powder XRD Patterns by Using the DASH Program Package

Structures of some hydrogenated products and intermediates, prepared by a heterogeneous Pd/C or Ru/C catalyst starting from 4-pyridinecarbonitrile (4PN), in water and in the presence of an acidic additive (HCl or H2SO4), were confirmed in various salt forms of 4-piperidylmethylamine (4PIPA) and 4-pyridylmethylamine (4PA). Crystallographic unit cell structure of the completely hydrogenated product salts (4PIPA·H2SO4 and 4PIPA·2HCl) showed a common double-protonated [4PIPA+2H]2+ divalent cation structure, also proved by FT-IR, and that of the 4PA·H2SO4 intermediate salt was also indexed and modeled by means of powder X-ray diffraction, applying the DASH 4.0 software package and crystal coordinates coming from former single-crystal X-ray structure determination. Formations of the anhydrous and hydrated forms of 4PA·0.5H2SO4·xH2O (x = 0 or x = 0.5, hemisulfates) were also studied by powder XRD and FT-IR spectroscopy for comparing these crystal structures.

The first examples of dirhenium(III,II) paramagnetic complexes with bridging diphenylphosphinomethane and 2-mercaptopyridine ligands: A collective experimental and theoretical studies

2-mercaptopyridine (H-pySH), 5‑chloro-2-mercaptopyridine (Cl-pySH) and 5-trifluoromethyl-2-mercaptopyridine (F3C-pySH) ligands react with the multiply‒bonded paramagnetic dirhenium(III,II) complex [Re2(μ-O2CCH3)Cl4(μ-dppm)2] (1) [dppm is Ph2PCH2PPh2] in refluxing ethanol to afford the paramagnetic substitution products of the type [Re2(μ-dppm)2(μ-R-pyS)2Cl2]Cl (2(R)) [R = H, Cl, CF3]. These are the first examples of paramagnetic dirhenium complexes that contain the bridging mercaptopyridine ligand. These complexes have very similar spectral (UV–vis, IR, EPR) and electrochemical properties which are also reported. The identity of 2(H) and 2(CF3) has been established by single-crystal X-ray structure determination (ReRe distance ∼2.29 Å). The electronic structures and optical properties of the complexes are scrutinized by density functional theory (DFT) and time-dependent DFT studies. DFT calculation shows that the highest occupied molecular orbital (HOMO) corresponds to a δ* interaction between the d-orbitals of rhenium atoms and π* interaction between the sulphur atoms and the rhenium centers whereas the lowest unoccupied molecular orbital (LUMO) is the Re2π* based orbital.

A Direct Route to closo-SBnCln Thiaboranes from Simple Electron-Precise Synthons: The Different Role of Chalcogen Bonding in SB5Cl5 and SB11Cl11 Crystals.

Six-vertex closo-SB5Cl5 (1) and ten-vertex closo-1-SB9Cl9 (2) thiaboranes have been prepared, besides the already known 12-vertex closo-SB11Cl11 (3), from the co-pyrolysis reaction of B2Cl4 with S2Cl2 at 280 °C in vacuo. The compounds are sublimable, off-white solids. Their elemental composition has been determined by high-resolution mass spectrometry. They were further characterized by one- and two-dimensional 11B NMR spectroscopy and X-ray structure determination for 1 and 3. Ab initio/GIAO/NMR computations support octahedral, bicapped square-antiprismatic, and icosahedral geometries for 1, 2 and 3, respectively, as expected based on their closo-electron counts. 1 is the first isolated example of a neutral polyhedral closo-thiaborane with a cluster size smaller than ten vertices. The solid-state structure of 3 is one of the rare examples of a single-crystal X-ray structure determination of an icosahedral heteroborane reported. The corresponding crystal-packing forces show the different role of chalcogen bonding in these octahedral and icosahedral crystals. In addition, there is a mass-spectrometry evidence for the recurrent formation of further thiaborane homologs of closo-SBnCln with n=4, 6, 10, and supra-icosahedral 12.

Synthesis, characterization, and biological activity of a fresh class of sonochemically synthesized Cu2+ complexes

The synthesis and characterization of metal complexes have garnered significant attention due to their versatile applications in scientific and biomedical fields. In this research, two novel copper (Cu) complexes, [Cu(L)(L′)(H2O)2] (1) and [Cu(L)(Im)H2O] (2), where L = pyridine-2,6-dicarboxylic acid, L′ = 2,4-diamino-6-hydroxypyrimidine, and Im = imidazole, were investigated concerning their sonochemical synthesis, spectroscopic analysis, and biological activity. The complexes’ structural characterization was achieved using analytical techniques, including single-crystal X-ray structure determination, FTIR, PXRD, TGA and DTA, SEM, TEM, and EDS. Complex (1) displayed a six-coordinated Cu2+ ion, while complex (2) exhibited a five-coordinated Cu2+ ion. The crystal structures revealed monoclinic (C2/c) and triclinic (P-1) space groups, respectively. Both complexes showcased zero-dimensional (0D) supramolecular networks, primarily driven by hydrogen bonding and π–π stacking interactions, which played pivotal roles in stabilizing the structures and shaping the unique supramolecular architecture. Both complexes demonstrated significant antioxidant activity, suggesting their capability to neutralize free radicals and mitigate oxidative stress-related diseases. Hemolysis percentages were less than 2%, per the ASTM F756-00 standard, indicating non-hemolytic behavior. Low cytotoxicity was observed against fibroblast and MCF-7 cell lines. They do not exhibit antibacterial activity against Escherichia coli and Staphylococcus aureus. These findings suggest that the synthesized Cu2+‒complexes hold considerable promise for applications in drug delivery and cancer treatment. This research contributes to the advancement of supramolecular chemistry and the development of multifunctional materials for diverse scientific and medical applications.

Synthesis, crystal structure and Hirshfeld surface analysis of [1-(4-bromo-phen-yl)-1H-1,2,3-triazol-4-yl]methyl 2-(4-nitro-phen-oxy)acetate.

The title compound, C17H13BrN4O5, was synthesized by a Cu2Br2-catalysed Meldal-Sharpless reaction between 4-nitro-phen-oxy-acetic acid propargyl ether and para-bromo-phenyl-azide, and characterized by X-ray structure determination and 1H NMR spectroscopy. The mol-ecules, with a near-perpendicular orientation of the bromo-phenyl-triazole and nitro-phen-oxy-acetate fragments, are connected into a three-dimensional network by inter-molecular C-H⋯O and C-H⋯N hydrogen bonds (confirmed by Hirshfeld surface analysis), π-π and Br-π inter-actions.

Chinese-Lantern shaped [MnII2MnIII6NaI3] cluster assembled from Schiff base and azide bridges: Synthesis, magnetic study and catecholase-like activity

A multisite Schiff base, H2damp, derived from the condensation of o-vanillin and a sterically constrained amino-alcohol (2-amino-2-methylpropan-1-ol) was utilized to isolate a new mixed valence heterometallic complex [Na3MnIII6MnII2(damp)6(µ4-O)2(µ1,3-O2CCH3)2(µ1,1-N3)6(µ1,1,3-N3)(H2O)2]·5H2O·CH3OH (1). Room temperature reaction of H2damp in MeOH with Mn(II) acetate and NaN3 provided the complex having MnII2MnIII6NaI3 core. X-ray structure determination revealed the use of azide ancillary ligands for the growth of the complex on ligand-bound MnIII3O fragments. The variable temperature magnetic characterization of 1 revealed intramolecular anti-ferromagnetic exchange interactions. Complex 1 also showed catalytic property for the aerial oxidation of 3,5-di-tert-butyl catechol (3,5-DTBCH2) with a turnover number (kcat) of 392 h−1. EPR and mass spectrometric analysis established the probable mechanism of catalytic oxidase reactivity on the model substrate. In EPR study the characteristic peak at g ∼ 2 allowed us to spot the presence of an organic radical confirming the conversion of DTBCH2 to DTBQ in radical pathway.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, and Computational Approach of a New Pyrazolo[3,4-g]isoquinoline Derivative as Potent against Leucine-Rich Repeat Kinase 2 (LRRK2).

Ethyl-2-((8-cyano-3,5,9a-trimethyl-1-(4-oxo-4,5-dihydrothiazol-2-yl)-4-phenyl-3a,4,9,9a-tetrahydro-1H-pyrazolo[3,4-g]isoquinolin-7-yl)thio)acetate (5) was synthesized, and its structure was characterized by IR, MS, and NMR (1H and 13C) and verified by a single-crystal X-ray structure determination. Compound 5 adopts a "pincer" conformation. In the crystal, the hydrogen bonds of -H···O, C-H···O, and O-H···S form thick layers of molecules that are parallel to (101). The layers are linked by C-H···π(ring) interactions. The Hirshfeld surface analysis shows that intermolecular hydrogen bonding plays a more important role than both intramolecular hydrogen bonding and π···π stacking in the crystal. The intramolecular noncovalent interactions in 5 were studied by QTAIM, NCI, and DFT-NBO calculations. Based on structural activity relationship studies, leucine-rich repeat kinase 2 (LRRK2) was found to bind 5 and was further subjected to molecular docking studies, molecular dynamics, and ADMET analysis to probe potential drug candidacy.

Досвід лікування конкрементів сечовидільних шляхів у дітей

Aim - to analyze the treatment of children with urolithiasis (urolithiasis), taking into account the location of stones in the urinary tract, their size and density, to select further individual patient management tactics. Materials and methods. The study included 48 patients with single urinary tract stones aged 6 months to 18 years. X-ray structural analysis and determination of the chemical composition was carried out with 39 stone fragments. Results. In 5 (10.4%) patients with calculi in the distal part of the ureter up to 5 mm in size, medical expulsive therapy was started. 17 (35.4%) patients with kidney and ureter calculi measuring 6-14 mm and density up to 900 HU underwent extracorporeal shock wave lithotripsy. In 3 (6.3%) patients with kidney and ureter calculi 6-14 mm in size and with a density of more than 900 HU, ureterorenoscopy (URS) and extraction using a Dormia basket or forceps to capture fragments were performed. 20 (41.7%) children with kidney stones larger than 15 mm or density greater than 1200 HU underwent contact lithotripsy. Contact endovesical lithotripsy was performed in 2 (4.2%) patients with massive calculi in the urinary bladder who underwent cystoplasty for an exstrophy-epispadias malformation. Results of X-ray structural stones analysis: calcium oxalate (wevelite, wedelite) - 31 (79.5%), calcium phosphate (hydroxyapatite) - 5 (12.8%), brushite - 2 (5.1%), cystine - 1 (2.6%). Conclusions. Modern minimally invasive technologies make it possible to remove calculi of any density and localization from the urinary system in a minimally traumatic, effective and sufficiently safe manner, regardless of the age of the child. In the treatment of urolithiasis in children, it is advisable to follow a personalized approach with the step-by-step use of the optimal arsenal of means to remove the stone. The research was carried out in accordance with the principles of the Helsinki declaration. The study protocol was approved by the local ethics committee of the listed institution. Informed consent of children and their parents was obtained for the research. No conflict of interest was declared by the authors.

A Phosphine-Oxide Cobalt(II) Complex and Its Catalytic Activity Studies toward Alcohol Dehydrogenation Triggered Direct Synthesis of Imines and Quinolines.

Herein, a new pincer-like amino phosphine donor ligand, H2L1, and its phosphine-oxide analog, H2L2, were synthesized. Subsequently, cobalt(II) complexes 1 and 2 were synthesized by the reaction of anhydrous Co(II)Cl2 with ligands H2L1 and H2L2, respectively. The ligands and complexes were fully characterized by various physicochemical and spectroscopic characterization techniques. Finally, the identity of the complexes 1 and 2 was confirmed by single crystal X-ray structure determination. The phosphine ligand containing complex 1 was converted to the phosphine oxide ligand containing complex 2 in air in acetonitrile solution. Both complexes 1 and 2 were investigated as precatalysts for alcohol dehydrogenation-triggered synthesis of imines in air. The phosphine-oxide complex 2 was more efficient than the phosphine complex 1. A wide array of alcohols and amines were successfully reacted in a mild condition to result in imines in good to excellent yields. Precatalyst 2 was also highly efficient for the synthesis of varieties of quinolines in air. As H2L2 in 2 has side arms that can be deprotonated, we investigated complex 2 for its base (KOtBu) promoted deprotonation events by various spectroscopic studies and DFT calculations. These studies have shown that mono deprotonation of the amine side arm attached to the pyridine is quite feasible, and deprotonation of complex 2 leads to a dearomatized pyridyl ring containing complex 2a. The mechanistic investigations of the catalytic reaction, by a combination of experimental and computational studies, have suggested that the dearomatized complex, 2a acted as an active catalyst. The reaction proceeded through the hydride transfer pathway. The activation barrier of this step was calculated to be 26.5 kcal/mol, which is quite consistent with the experimental reaction temperature under aerobic conditions. Although various pincer-like complexes are explored for such reactions, phosphine oxide ligand-containing complexes are still unexplored.

Thiosalicylanilide complexes of nickel(II), palladium(II) and platinum(II)

Reactions of the complexes cis-[PtCl2(PPh3)2], [PtCl2(dppf)] {dppf = Fe(C5H4PPh2)2}, [PdCl2(PPh3)2], [PdCl2(dppe)] (dppe = Ph2PCH2CH2PPh2) and [NiCl2(dppe)] with thiosalicylanilide (HSC6H4CONHPh, H2-1a) and its substituted derivatives H2-1b to H2-1d (where H2-1b = p-Cl-HSC6H4CONHPh, H2-1c = p-CH3-HSC6H4CONHPh, and H2-1d = m-OCH3-HSC6H4CONHPh) gave a series of square-planar MS2P2-type complexes. The complexes were characterised by ESI MS, 1H and 31P{1H} NMR, FTIR, and microelemental analyses, and in some cases by single crystal X-ray crystallography. The predominant coordination mode is through bonding of deprotonated thiol group of two ligands. However, the tendency to form complexes with a single, chelating S,N- and S,O-donor ligand was observed by 31P{1H} NMR in some reactions. In addition, cis/trans isomerisation was observed in some complexes by 31P{1H} NMR and confirmed by X-ray structure determinations on trans-[Pt(H-1b)2(PPh3)2] and trans-[Pd(H-1b)2(PPh3)2]. A comparison of the energetics of the reaction systems involving [Pt(1b)(PPh3)2]/[Pt(H-1b)2(PPh3)2], [Pt(1d)(PPh3)2]/[Pt(H-1d)2(PPh3)2] and [Pd(1b)(dppe)]/[Pd(H-1b)2(dppe)] using Density Functional Theory (DFT) revealed that the MS2P2 systems [Pt(H-1b)2(PPh3)2], [Pt(H-1d)2(PPh3)2] and [Pd(H-1b)2(dppe)] have lower Gibbs free energies than the S,N-chelate systems [Pt(1b)(PPh3)2], [Pt(1d)(PPh3)2] and [Pd(1b)(dppe)], and are thermodynamically favoured. Intermolecular interactions quantified and visualized on Hirshfeld surfaces for trans-[Pt(H-1b)2(PPh3)2], [Pt(H-1d)2(PPh3)2].H2O, and [Pd(H-1a)2(dppe)] revealed the dominant contribution of H···H contacts to crystal packing.

Further Insight into the Manganese(II) 2,2′-Bipyridine-1,1′-dioxide Homoleptic Complex: Single-Crystal X-ray Structure Determination of the Perchlorate Salt and DFT Calculations

The homoleptic cationic complex formed by reacting suitable manganese(II) salts with 2,2′-bipyridine-1,1′-dioxide (bipyO2) has been subjected to several studies in the past because of its peculiar absorption and electrochemical features. Here, the first single-crystal X-ray structure determination of a [Mn(bipyO2)3]2+ salt is reported, where the charge of the cation is balanced by perchlorate anions. The hydrated salt [Mn(bipyO2)3](ClO4)2 crystallizes in the monoclinic system (P21/n space group) and the asymmetric unit contains three cationic complexes and six perchlorate anions. The environment of the manganese(II) ions is best described as octahedral, with scarce variations among the three cations in the asymmetric unit. The bipyO2 ligands exhibit κ2 coordination mode, forming seven-membered metallacycles. The X-ray outcomes have been used as the starting point for DFT and TDDFT calculations, aimed to elucidate the charge transfer origin of the noticeable absorption in the visible range. The MLCT nature is confirmed by the hole and electron distributions associated with the spin-allowed transitions. DFT calculations on the related manganese(III) complex indicate that the geometry of [Mn(bipyO2)3]2+ changes only slightly upon oxidation, in agreement with the reversible electrochemical behaviour experimentally observed.

Unusual Stabilisation of Remarkably Bent Tetra-Cationic Tetra-radical Intermolecular Fe(III) μ-Oxo Tetranuclear Complexes.

A hitherto unknown series of air stable, π-conjugated, remarkably bent tetra-cation tetra-radical intermolecular Fe(III) μ-oxo tetranuclear complex, isolated from the dication diradical diiron(III) porphyrin dimers, has been synthesised and spectroscopically characterised along with single crystal X-ray structure determination of two such molecules. These species facilitate long-range charge/radical delocalisation through the bridge across the entire tetranuclear unit manifesting an unusually intense NIR band. Assorted spin states of Fe(III) centres are stabilised within these unique tetranuclear frameworks: terminal six-coordinate iron centres stabilise the admixed intermediate spin states while the central five-coordinate iron centres stabilise the high-spin states. Variable temperature magnetic susceptibility measurements indicated strong antiferromagnetic coupling for the Fe(III)-O-Fe(III) unit while the exchange interactions between the Fe centres and the porphyrin π-cation radicals are weaker as supported both by magnetic data and DFT calculations. The nature of orbital overlap between the SOMOs of Fe(III) and π* orbital of the porphyrin was found to rationalise the observed exchange coupling, establishing such a complex magnetic exchange in this tetranuclear model with a significant bioinorganic relevance.

Diverse Reactivity of Amidinate-Supported Boron Centers with the Hypersilyl Anion and Access to a Monomeric Secondary Boron Hydride.

Diverse reactivity of the bulky tris(trimethylsilyl)silyl substituent [Si(SiMe3)3], also known as the hypersilyl group, was observed for amidinate-supported dichloro- and phenylchloroborane complexes. Treatment of the dichloroborane with potassium tris(trimethylsilyl)silyl led to the activation of the backbone β-carbon center and formation of saturated four-membered heterocyclic chloroboranes R'{Si(SiMe3)3}C(NR)2BCl [R' = Ph, R = Cy (3); R' = Ph, R = iPr (6); R' = tBu, R = Cy (8)], whereas the four-membered amidinate hypersilyl-substituted phenyl borane 4 {PhC(NCy)2B(Ph)[Si(SiMe3)3]} was observed for the case of an amidinate-supported phenylchloroborane. The highly deshielded 11B NMR spectroscopic resonance and the distinct difference in the 29Si NMR spectrum confirmed the presence of a σ-donating hypersilyl effect on compounds 3, 6, and 8. Reaction of 3 with the Lewis acid AlCl3 led to the formation of complex 11 in which an unusual cleavage of one of the C-N bonds of the amidinate backbone is observed. Nucleophilic substitution at the boron center of saturated chloroborane 3 with phenyllithium generated the phenylborane derivative 12, whereas the secondary monomeric boron hydride 13 was observed after treatment with alane (AlH3). All compounds (2-13) have been fully characterized by NMR spectroscopy and single-crystal X-ray structure determination studies.

Na3Ge2P3: A Zintl Phase Featuring [P3Ge-GeP3] Dimers as Building Blocks.

Recently, ternary lithium phosphidotetrelates have attracted interest particularly due to their high ionic conductivities, while corresponding sodium and heavier alkali metal compounds have been less investigated. Hence, we report the synthesis and characterization of the novel ternary sodium phosphidogermanate Na3Ge2P3, which is readily accessible via ball milling of the elements and subsequent annealing. According to single crystal X-ray structure determination, Na3Ge2P3 crystallizes in the monoclinic space group P21/c (no. 14.) with unit cell parameters of a = 7.2894(6) Å, b = 14.7725(8) Å, c = 7.0528(6) Å, β = 106.331(6)° and forms an unprecedented two-dimensional polyanionic network in the b/c plane of interconnected [P3Ge-GeP3] building units. The system can also be interpreted as differently sized ring structures that interconnect and form a two-dimensional network. A comparison with related ternary compounds from the corresponding phase system as well as with the binary compound GeP shows that the polyanionic network of Na3Ge2P3 resembles an intermediate step between highly condensed cages and discrete polyanions, which highlights the structural variety of phosphidogermanates. The structure is confirmed by 23Na- and 31P-MAS NMR measurements and Raman spectroscopy. Computational investigation of the electronic structure reveals that Na3Ge2P3 is an indirect band gap semiconductor with a band gap of 2.9 eV.

Structures of LIG1 provide a mechanistic basis for understanding a lack of sugar discrimination against a ribonucleotide at the 3'-end of nick DNA

Human DNA ligase 1 (LIG1) is the main replicative ligase that seals Okazaki fragments during nuclear replication and finalizes DNA repair pathways by joining DNA ends of the broken strand breaks in the three-steps of ligation reaction. LIG1 can tolerate the RNA strand at the upstream of the nick, yet an atomic insight into the sugar discrimination mechanism by LIG1 against a ribonucleotide at the 3'-terminus of nick DNA is unknown. Here, we determined X-ray structures of LIG1/3'-RNA-DNA hybrids and captured the ligase during pre- and post-step 3 the ligation reaction. Furthermore, the overlays of 3'-rA:T and 3'-rG:C step 3 structures with step 2 structures of canonical 3'-dA:T and 3'-dG:C uncover a network of LIG1/DNA interactions through Asp570 and Arg871 side chains with 2'-OH of the ribose at nick showing a final phosphodiester bond formation and the other ligase active site residues surrounding the AMP site. Finally, we demonstrated that LIG1 can ligate the nick DNA substrates with preinserted 3'-ribonucleotides as efficient as Watson-Crick base-paired ends in vitro. Together, our findings uncover a novel atomic insight into a lack of sugar discrimination by LIG1 and the impact of improper sugar on the nick sealing of ribonucleotides at the last step of DNA replication and repair.

Functional Model of Compound II of Cytochrome P450: Spectroscopic Characterization and Reactivity Studies of a FeIV-OH Complex.

Herein, we show that the reaction of a mononuclear FeIII(OH) complex (1) with N-tosyliminobenzyliodinane (PhINTs) resulted in the formation of a FeIV(OH) species (3). The obtained complex 3 was characterized by an array of spectroscopic techniques and represented a rare example of a synthetic FeIV(OH) complex. The reaction of 1 with the one-electron oxidizing agent was reported to form a ligand-oxidized FeIII(OH) complex (2). 3 revealed a one-electron reduction potential of -0.22 V vs Fc+/Fc at -15 °C, which was 150 mV anodically shifted than 2 (Ered = -0.37 V vs Fc+/Fc at -15 °C), inferring 3 to be more oxidizing than 2. 3 reacted spontaneously with (4-OMe-C6H4)3C• to form (4-OMe-C6H4)3C(OH) through rebound of the OH group and displayed significantly faster reactivity than 2. Further, activation of the hydrocarbon C-H and the phenolic O-H bond by 2 and 3 was compared and showed that 3 is a stronger oxidant than 2. A detailed kinetic study established the occurrence of a concerted proton-electron transfer/hydrogen atom transfer reaction of 3. Studying one-electron reduction of 2 and 3 using decamethylferrocene (Fc*) revealed a higher ket of 3 than 2. The study established that the primary coordination sphere around Fe and the redox state of the metal center is very crucial in controlling the reactivity of high-valent Fe-OH complexes. Further, a FeIII(OMe) complex (4) was synthesized and thoroughly characterized, including X-ray structure determination. The reaction of 4 with PhINTs resulted in the formation of a FeIV(OMe) species (5), revealing the presence of two FeIV species with isomer shifts of -0.11 mm/s and = 0.17 mm/s in the Mössbauer spectrum and showed FeIV/FeIII potential at -0.36 V vs Fc+/Fc couple in acetonitrile at -15 °C. The reactivity studies of 5 were investigated and compared with the FeIV(OH) complex (3).

Reduction of Germanium Oxides-The Mixed-Valence Germanates A2Ge4O7 (A = Na, K).

We report on the synthesis of two-layered alkali germanates, Na2Ge4O7 and K2Ge4O7. Both compounds were synthesized by using the ammonothermal method at 823 K and 100 MPa. Under these conditions, germanium is partially reduced from the +IV state to +II, forming mixed-valence compounds with the rarely observed [Ge(II)O3]4- unit. The valence state was verified by X-ray photoelectron spectroscopy (XPS) and was accompanied by theoretical calculations alongside vibrational spectroscopy and single-crystal X-ray structure determination. The compounds crystallize in the trigonal space groups (Na2Ge4O7: P3̅c1 and K2Ge4O7: P3̅m1) and feature layers of corner sharing [Ge(II)O3]4- and [Ge(IV)2O7]6- units forming [Ge(II)2Ge(IV)2O7]2- polyanions. These layers are separated by alkali metal ions. The compounds are colorless insulators with band gaps of 4.0-4.2 eV. According to the Robin-Day classification, both compounds can be described as class I materials, where the valences are trapped on specific sites.