Chain structures in alkali metal borophosphates: synthesis and characterization of K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2

Two new alkali metal borophosphates, K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2], were synthesized by applying solvothermal techniques using ethanol as solvent. The crystal structures were solved by means of single-crystal X-ray diffraction (K3[BP3O9(OH)3], monoclinic, C2/c (No. 15), a = 2454.6(8) pm, b = 736.3(2) pm, c = 1406.2(4) pm, beta = 118.35(2) degrees , Z = 8; Rb3[B2P3O11(OH)2], monoclinic, P2(1)/c (No. 14), a = 781.6(2) pm, b = 667.3(2) pm, c = 2424.8(5) pm, beta = 92.88(1) degrees , Z = 4). Both crystal structures comprise borophosphate chain anions. While for the rubidium compound a loop-branched chain motif is found as common for most of the chain anions in alkali metal borophosphates, the crystal structure of the potassium phase comprises the first open-branched chain with the highest phosphate content found so far in this group of compounds. Both chain anions are closely related to known anhydrous or hydrated phases, and the structural relations are discussed in terms of how the presence of OH groups and hydrogen bonds as well as number, charge, and size of charge balancing cations influence the 3D structural arrangement. The anionic entities are classified in terms of general principles of structural systematics for borophosphates.     

A Structurally Robust Chiral Borate Ion: Molecular Design,Synthesis, and Asymmetric Catalysis

Catalysis by chiral weakly‐coordinating anions (WCAs) remains underdeveloped due to the lack of a molecular design strategy for exploiting their characteristics, such as the non‐nucleophilic nature. Here, we report the development of a chiral borate ion comprising an O,N,N,O‐tetradentate backbone, which ensures hitherto unattainable structural robustness. Upon pairing with a proton, the hydrogen borate acts as an effective catalyst for the asymmetric Prins‐type cyclization of vinyl ethers, providing access to structurally and stereochemically defined dihydropyrans. The key to selectivity control is the distinct ability of the borate ion to discriminate the prochiral faces of the acyclic oxonium ion intermediate and dictate the regiochemical outcome. We anticipate that this study paves the way for exploring the untapped potential of WCA catalysis for selective chemical synthesis.     

Synthesis,structure characterization,photoluminescence properties and TD–DFT calculations for two new borates

Due to their rich structural chemistry and wide variety of applications, borate materials have provided a rich area of research. In a continuation of this research, diethylammonium bis(2‐oxidobenzoato‐κ²O¹,O²)borate, C₄H₁₂N⁺·BO₄(C₇H₄O)₂⁻, (1), and propylammonium bis(2‐oxidobenzoato‐κ²O¹,O²)borate, C₃H₁₀N⁺·BO₄(C₇H₄O)₂⁻, (2), have been synthesized by the reaction of boric acid with salicylic acid under ambient conditions. In both structures, the B atom exhibits a slightly distorted tetrahedral environment formed by the bidentate coordination of two salicylate anions via the O atoms of the central carboxylate and oxide groups. In the crystals of salts (1) and (2), mixed cation–anion layers lying parallel to the (101) plane are formed through N—H…O, C—H…O and C—H…π/N—H…O hydrogen‐bonding interactions, resulting, in each case, in a two‐dimensional supramolecular architecture in the solid state. The photoluminescence properties of the salts were studied using the as‐synthesized samples and reveal that salts (1) and (2) both display a strong blue‐light emission, with maxima at 489 and 491 nm, respectively. In DFT/TD–DFT (time‐dependent density functional theory) studies, the blue emission appears to be derived from an intramolecular charge transfer (ICT) excited state. In addition, IR and UV–Vis spectroscopies were used to investigate the title salts.     

Haloacyl complexes of boron, [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I)

The haloacyltris(trifluoromethyl)borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been synthesized by reacting (CF3)3BCO with either MHal (M=K, Cs; Hal=F) in SO2 or MHal (M=[nBu4N]+, [Et4N]+, [Ph4P]+; Hal=Cl, Br, I) in dichloromethane. Metathesis reactions of the fluoroacyl complex with Me3SiHal (Hal=Cl, Br, I) led to the formation of its higher homologues. The thermal stabilities of the haloacyltris(trifluoromethyl)borates decrease from the fluorine to the iodine derivative. The chemical reactivities decrease in the same order as demonstrated by a series of selected reactions. The new [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br) salts are used as starting materials in the syntheses of novel compounds that contain the (CF3)3B-C fragment. All borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been characterized by multinuclear NMR spectroscopy (11B, 13C, 17O, 19F) and vibrational spectroscopy. [PPh4][(CF3)3BC(O)Br] crystallizes in the monoclinic space group P2/c (no. 13) and the bond parameters are compared with those of (CF3)3BCO and K[(CF3)3BC(O)F]. The interpretation of the spectroscopic and structural data are supported by DFT calculations [B3LYP/6-311+G(d)].     

(Aceto­nitrile)­[2,6‐bis­(pyrazol‐1‐yl)­pyridine](isonicotin­amide)copper(II)–tetra­fluoro­borate–aceto­nitrile (1/2/2)

Molecules of the title compound, [Cu(C₂H₃N)(C₁₁H₉N₅)(C₆H₆N₂O)](BF₄)₂·2C₂H₃N, comprise (aceto­nitrile)[2,6‐bis(pyrazol‐1‐yl)­pyridine](isonicotin­amide)copper(II) cations, tetra­fluoro­borate anions and lattice aceto­nitrile mol­ecules. The cations have distorted square‐pyramidal geometries in which the N₃‐donor, viz. 2,6‐bis­(pyrazol‐1‐yl)­pyridine, and the N‐donor, viz. the isonicotin­amide ligand, occupy the four basal positions, with the coordinated aceto­nitrile N‐donor atom occupying the apical position. Pairs of cations are linked by N—H?F hydrogen bonds through tetra­fluoro­borate anions, forming centrosymmetric dimers, which are further linked by C—H?O hydrogen bonds into two‐dimensional undulating sheets, three of which interpenetrate to generate a two‐dimensional network.     

Stanna‐closo‐dodecaborate: A New Ligand in Coordination Chemistry

Most of the divalent compounds of tin have a lone pair and hence can act as donors. In tin‐transition metal chemistry neutral molecules as well as anions have been studied as ligands. This research report summarizes recent research on coordination compounds with a closo‐heteroborate cage compound stanna‐closo‐dodecaborate [SnB₁₁H₁₁]^2?. The syntheses of the first coordination compounds and studies on the ligand abilities of this tin borate are discussed in this article.     

MgO·3B2O3·3.5H2O的合成、表征及其溶液Raman光谱分析

硼是具有独特化学行为的稀有亲氧元素，在自然界中主要是以无机硼氧酸和硼氧酸盐形式存在。在硼酸盐晶体中，硼以聚合硼氧配阴离子形式存在，其中配位数为３和４的硼原子比可以有所不同，这使得硼酸盐种类繁多，结构复杂多样。至今，人们在自然界和实验室已发现了４种六硼酸镁盐犤１，２犦：MgO·３B２O３·nH２O（n＝７．５，７，６，５），它们的分子结构中都含有犤B６O７（OH）６犦２－基团。最近，我们在硼酸盐化学系列研究中，利用复盐氯柱硼镁石在沸点温度下的硼酸溶液中的相转化，合成了一种新的六硼酸镁盐MgO·３B２O３·３．…     

CsSc[B2P3O11(OH)3]: a new borophosphate oligomer containing boron in three- and fourfold coordination

CsSc[B2P3O11(OH)3] was obtained by hydrothermal synthesis and represents the first alkali-metal scandium borophosphate containing boron with coordination numbers 3 and 4. The crystal structure was determined from single-crystal X-ray data: orthorhombic, space group Pnna (No. 52), a=13.0529(15) A, b=18.3403(17) A, c=10.3838(12) A, Z=8. The crystal structure contains the oligomeric unit [B2P3O11(OH)3]4- in which a central borate tetrahedron is open-branched by two (OH)PO3 tetrahedra and cyclobranched by one PO4 tetrahedron and a trigonal-planar (OH)BO2 by sharing common apexes. The borophosphate oligomers together with the ScO6 octahedra are condensed to form layers. Simultaneous difference thermal analysis and thermogravimetry revealed the stepwise decomposition of the compound in the temperature range between 333 and 973 K. Partly dehydrated samples do not show any substantial rehydration behavior. The crystal structure of CsSc[B2P3O11(OH)3] is discussed in connection with structural motifs of related borates and borophosphates.     

Structural chemistry of silicates: new discoveries and ideas

The new tetrahedral complexes revealed in the structures of natural silicates in the last years are analyzed. Several new minerals and structural types widen the structural classification and principles of silicates. The new structures of silicates with mixed anions are formed by stacking of similar units, and thus they can be described in terms of the modular approach and its polysomatic concepts. The difference between the silicate minerals of the Earth’s crust and mantle is considered. Possible mineral transformations occurring in the mantles of the Earth and extrasolar planets are described.     

Chiral bis(mandelato)borate salts for resolution via metathesis crystallization

Spiroborate anions have potential for crystallization or resolution and chiral bis(mandelato)borate anions can be used for the efficient resolution of a diverse range of racemic cations via diastereomeric salt formation. The syntheses, X‐ray crystal structures and solubilities of three chiral bis(mandelato)borate salts, namely poly[[aqua‐μ₃‐bis[(R )‐mandelato]borato‐lithium(I)] monohydrate], [Li(C₁₆H₁₂BO₆)(H₂O)]_n or Li[B(R‐Man)₂]·H₂O, (1), ammonium bis[(R )‐mandelato]borate, NH₄⁺·C₁₆H₁₂BO₆⁻ or NH₄[B(R‐Man)₂], (2), and tetra‐n‐butylammonium bis[(R )‐mandelato]borate, C₁₆H₃₆N⁺·C₁₆H₁₂BO₆⁻ or NBu₄[B(R‐Man)₂], (3), are reported. They all have a B_S configuration and show a reasonably well‐conserved anion geometry. The main conformational variation is the orientation of the two phenyl groups, supporting the idea that [B(Man)₂]⁻ is a semi‐rigid anion. The salts are differentially soluble in a range of solvents, meaning they could be useful as reagents for resolution via a metathesis crystallization approach.     

Preparation and Characterization of New C2‐ and C1‐Symmetric Nitrogen,Oxygen, Phosphorous,and Sulfur Derivatives and Analogs of TADDOL. Part III

A brief overview is presented of the field of organocatalysis using chiral H‐bond donors, chiral Brønsted acids, and chiral counter‐anions (Fig. 1). The role of TADDOLs (=α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanols) as H‐bond donors and the importance of an intramolecular H‐bond for acidity enhancement are discussed. Crystal structures of TADDOLs and of their N‐, S‐, and P‐analogs (Figs. 2 and 3) point the way to proposals of mechanistic models for the action of TADDOLs as organocatalysts (Scheme 1). Simple experimental two‐step procedures for the preparation of the hitherto strongest known TADDOL‐derived acids, the bicyclic phosphoric acids ( 2 in Scheme 2) and of a phosphoric‐trifluorosulfonic imide ( 9 in Scheme 4), are disclosed. The mechanism of sulfinamide formation in reactions of TADDAMIN with trifluoro‐sulfonylating reagents is discussed (Scheme 3). pK_a Measurements of TADDOLs and analogs in DMSO (reported in the literature; Fig. 5) and in MeO(CH₂)₂OH/H₂O (described herein; Fig. 6) provide information about further possible applications of this type of compounds as strong chiral Brønsted acids in organocatalysis.     

Synthesis and ab initio X‐ray powder diffraction structure of the new alkali and alkali earth metal borate NaCa(BO3)

A sodium calcium borate, NaCaBO₃, has been synthesized by the solid‐state reaction method and the structure solved from X‐ray powder diffraction data. The compound crystallizes in space group Pmmn and has a desired structure type containing isolated planar BO₃³⁻ anions. Mixed occupancy is found to exist in the Ca site, with partial replacement by Na. One Ca/Na mixed atom and one Na atom are at sites with mm2 symmetry, and a second Ca/Na mixed atom, an Na atom, two B and two O atoms are on mirror planes.     

dl‐Alaninium semi‐oxalate monohydrate

The structure of the title compound, C₃H₈NO₂⁺·C₂HO₄⁻·H₂O, is formed by two chiral counterparts (l ‐ and d ‐alaninium cations), semi‐oxalate anions and water molecules, with a 1:1:1 cation–anion–water ratio. The structure is compared with that of the previously known anhydrous dl ‐alaninium semi‐oxalate [Subha Nandhini, Krishnakumar & Natarajan (2001). Acta Cryst. E 57 , o666–o668] in order to investigate the role of water molecules in the crystal packing. The structure of the hydrate resembles that of anhydrous alaninium semi‐oxalate, with the water molecule incorporated into the general three‐dimensional network of hydrogen bonds where it forms four hydrogen bonds with neighbours disposed tetrahedrally about it. Although the main structural motifs in the hydrate and in the anhydrous form are topologically similar, the incorporation of water molecules in the network results in significant geometric distortion. There are several types of hydrogen bond in the crystal structure of the hydrate, two of which (O—H...O bonds between the semi‐oxalate anions and O—H...O hydrogen bonds between water and alaninium cations) are very short. Such hydrogen bonds between semi‐oxalate anions are also present in the anhydrous form of this compound. Short distances between semi‐oxalate anions in neighbouring chains in the hydrate alternate with longer ones, whereas in the anhydrous structure they are equidistant. Despite the similarity of these compounds, dehydration of the hydrate on storage is not of a single‐crystal to single‐crystal type, but gives a polycrystalline pseudomorph, preserving the crystal habit. This transformation proceeds through the formation of an intermediate compound, presumably a hemihydrate.     

An alkoxide cluster with 18 Li+ ions encapsulating two borate anions, [(tBuO)12Li18(BO3)2]

The title compound, bis­(borato)­dodeca(tert‐butoxo)­octa­deca­lithium, [Li₁₈(BO₃)₂(C₄H₉O)₁₂], is formulated conveniently as [{(^tBuOLi)₃(Li₃BO₃)}₂(^tBuOLi)₆]. A central 12‐membered ring and two outer six‐membered rings are formed by alternating Li⁺ cations and alkoxide O atoms. Sandwiched between the central ring and each of the outer rings is a planar array of three further Li⁺ cations surrounding a [BO₃]³⁻ anion. Thus, the mol­ecule consists of a cationic [Li₁₈(O^tBu)₁₂]⁶⁺ cage encapsulating two borate anions. This compound is the first example of a structurally characterized polynuclear lithium borate, and a rare case of a lithium alkoxide cage with nuclearity greater than eight. All the alkoxide ligands are triply bridging, and the lithium ions have trigonal‐planar, trigonal‐pyramidal and fourfold coordination, all with major distortions from regular coordination geometry.     

[M(en)3] (ndt)•H2O的水热合成、晶体结构和光学性能 ( M=NiⅡ, CoⅡ, MnⅡ and ndt=1,5-naphthalenedithiolate )

水热条件下，合成了三个新的配合物[Ni(en)₃] (ndt) ·H₂O 1, [Co(en)₃] (ndt) ·H₂O 2 和[Mn(en)₃] (ndt) ·H₂O 3。晶体结构通过X-射线单晶衍射进行了表征。三个配合物均属于单斜晶系，Cc空间群。[M(en)₃]²⁺阳离子、ndt阴离子和结晶水分子通过氢键自组装出相同结构的三维网。通过紫外-可见-近红外漫反射光谱对这三个配合物的光吸收性能和能带进行了测定。     

Lamellar aggregation and hydrogen‐bonding motifs in 3‐(amino­carbon­yl)­pyridinium perchlorate and hydrogen oxalate

In the title compounds, C₆H₇N₂O⁺·ClO₄⁻, (I), and C₆H₇N₂O⁺·C₂HO₄⁻, (II), the carboxamide plane is twisted from the plane of the protonated pyridine ring. Lamellar or sheet‐like structural features are observed through N—H⋯O and O—H⋯O hydrogen‐bonded motifs of cations and anions in (I) and (II), respectively. These sheets are aggregated through C(4) and C(5) chain motifs in (I) and (II), respectively. R₁²(4) ring motifs in (I) and R₁²(5) motifs in (II) are formed via pyridine–anion bifurcated N—H⋯O inter­actions. In (II), carboxamide groups form N—H⋯O dimers around the inversion centres of the unit cell, with R₂²(8) ring motifs. A 2₁ screw‐related helical or ribbon‐like structure along the b axis is formed in (II) through carboxamide and pyridinium N—H⋯O hydrogen bonds with the oxalate anions.     

Cation–Cation Pairing by NCH⋅⋅⋅O Hydrogen Bonds

The pairing of ions of opposite charge is a fundamental principle in chemistry, and is widely applied in synthesis and catalysis. In contrast, cation–cation association remains an elusive concept, lacking in supporting experimental evidence. While studying the structure and properties of 4‐oxopiperidinium salts [OC₅H₈NH₂]X for a series of anions X^? of decreasing basicity, we observed a gradual self‐association of the cations, concluding in the formation of an isolated dicationic pair. In 4‐oxopiperidinium bis(trifluoromethylsulfonyl)amide, the cations are linked by N? H???O?C hydrogen bonds to form chains, flanked by hydrogen bonds to the anions. In the tetra(perfluoro‐tert‐butoxy)aluminate salt, the anions are fully separated from the cations, and the cations associate pairwise by N? C? H???O?C hydrogen bonds. The compounds represent the first genuine examples of self‐association of simple organic cations based merely on hydrogen bonding as evidenced by X‐ray structure analysis, and provide a paradigm for an extension of this class of compounds.     

An approach to creating novel anions: silylated triel compounds with –CH2– and –O– linkers, [InCl2{O(HO)Si(t‐Bu)2}]2 and Li[B(CH2SiMe3)4]

Bis[μ‐di‐tert‐butyl(hydroxy)silanolato]bis[chloridoindium(III)], [In₂(C₈H₁₉O₂Si)₂Cl₄], (I), is a centrosymmetric two‐centre indium complex featuring a system of three annulated four‐membered rings; the structure is the first example of an In₂O₂ ring which is annulated with two Si—O units to form a ring system composed of three rings. The coordination environment of the In centres is a distorted trigonal bipyramid. The crystal packing of (I) is characterized by chains of molecules connected by O—H...Cl hydrogen bonds. The crystal of (I) was a nonmerohedral twin. There is no known example of an In₂O₂ ring in which the In atoms carry any two halogen ligands. The structure of tetrakis(tetrahydrofuran)lithium tetrakis[(trimethylsilyl)methyl]borate, [Li(C₄H₈O)₄](C₁₆H₄₄BSi₄), (II), is composed of discrete cations and anions. The coordination geometries of the Li and B centres is tetrahedral. The cations and anions lie in planes parallel to the ab plane. There are no short contacts between the cations and anions. Compound (II) is the first example of a B centre bonded to four –CH₂Si units.     

Dirubidium aqua­penta­chloro­chromate(III) and dicaesium aqua­penta­chloro­chromate(III)

The structures of the two novel title compounds, Rb₂[CrCl₅(H₂O)], (I), and Cs₂[CrCl₅(H₂O)], (II), have been determined by single‐crystal X‐ray diffraction. Compounds (I) and (II) crystallize with Pnma and Cmcm symmetry, respectively. In (I), the Cr, three Cl and water O atom lie on a mirror plane; in (II), the Cs, Cr, O and one of the Cl atoms are at sites with m2m symmetry. The chromate anions are in a pseudo‐cubic environment of eight Rb⁺ cations in (I) and in a pseudo‐octahedral environment of six Cs⁺ cations in (II). The structural arrangement correlates with the r_anion/r_cation radius ratio.     

Preparation,Structure, and Second‐order Nonlinear Optical Properties of a Borate‐Carboxylic Acid Compound: NH4B[d‐(+)‐C4H4O5]2·H2O

The organic‐inorganic hybrid nonlinear optical (NLO) material NH₄B(d‐ (+)‐C₄H₄O₅)₂ · H₂O (NBC) was synthesized in a borate‐carboxylic acid system. Its structure was determined by single crystal X‐ray diffraction. It crystallizes in the orthorhombic system, space group Pna2₁ (No. 33), with cell parameters a = 11.484(6) Å, b = 5.354(3) Å, c = 21.079(12) Å, V = 1296.0(12), Z = 4. It exhibits a three‐dimensional pseudo tunnel structure consisting of fundamental building block [B(d‐ (+)‐C₄H₄O₅)₂]^– anions. The small cavities are occupied by the H₂O molecules and NH₄⁺ cations, which stabilize the whole structure by O–H ··· O and N–H ··· O hydrogen bonds. The powder X‐ray diffraction (PXRD) of the crystal was also recorded. Elemental analyses, FT‐IR and FT‐Raman spectra analyses, thermal analysis, and diffuse‐reflectance spectra for the compound are also presented, as are band structures and density of states calculation. Nonlinear optical measurements indicate that the material has second harmonic generation (SHG) properties and is phase‐matchable.