Synergistic flame‐retardant effect and mechanisms of boron/phosphorus compounds on epoxy resins

To explore the component synergistic effect of boron/phosphorus compounds in epoxy resin (EP), 3 typical boron compounds, zinc borate (ZB), boron phosphate (BPO₄), and boron oxide (B₂O₃), blended with phosphaphenanthrene compound TAD were incorporated into EP, respectively. All 3 boron/phosphorus compound systems inhibited heat release and increased residue yields and exerted smoke suppression effect. Among 3 boron/phosphorus compound systems, B₂O₃/TAD system brought best flame‐retardant effect to epoxy thermosets in improving the UL94 classification of EP composites and also reducing heat release most efficiently during combustion. B₂O₃ can interact with epoxy matrix and enhance the charring quantity and quality, resulting in obvious condensed‐phase flame‐retardant effect. The combination of condensed‐phase flame‐retardant effect from B₂O₃ and the gaseous‐phase flame‐retardant effect from TAD effectively optimized the action distribution between gaseous and condensed phases. Therefore, B₂O₃/TAD system generated component synergistic flame‐retardant effect in epoxy thermosets.     

Reactions of dodecahydro-closo-dodecaboric acid with chitosan

A donor-acceptor interaction between H⁺-cations of dodecahydro-closo-dodecaboric acid and the amine group of chitosan results in the generation of chitosanium dodecahydro-closo-dodecaborate, (C₆O₄H₉NH₃)₂B₁₂H₁₂ — water-insoluble salt. The presence of four pairs of donor oxygen atoms in its composition makes for the existence of (C₆O₄H₉NH₃)₂B₁₂H₁₂× nH₂B₁₂H₁₂ (0 < n ≤ 4) compounds. When treating the latter with gaseos ammonia, the compounds of (C₆O₄H₉NH₃)₂B₁₂H₁₂×n(NH₄)₂B₁₂H₁₂ (0 < n ≤ 4) composition are formed. The individuality of the compounds was confirmed by IR and X-ray PE spectral studies, chemical and X-ray phase analyses, and thermogravimetry.     

Synthesis,Crystal Structure,and Characterization of a Novel Metallo‐Organically‐Templated Pentaborate with Mixed Ligands

A novel metallo‐organically templated pentaborate with layered framework, [Cd(TETA)(C₂H₃O₂)][B₅O₆(OH)₄] ( 1 ) (TETA = triethylenetramine), was synthesized under mild solvothermal conditions. The structure was determined by single‐crystal X‐ray diffraction and further characterized by FT‐IR spectroscopy, elemental analysis, thermogravimetric analysis, and photoluminescence spectroscopy. The structure consists of an isolated polyborate anion [B₅O₆(OH)₄]^– and the cadmium complex cation of [Cd(TETA)(C₂H₃O₂)]⁺, which contains both organic amine and organic acid ligands. The [B₅O₆(OH)₄]^– units are connected together by hydrogen bonds, and a 2D sheet‐like framework with rectangle‐like 12‐membered boron rings are formed. The [Cd(TETA)(C₂H₃O₂)]⁺ complex cations are located in the free space between the layers and connect the adjacent borate layers through hydrogen bonds to form a three‐dimensional supramolecular network. The luminescent properties of the compound were studied for the first time in the series of metallo‐organically‐templated pentaborates, and a blue luminescence occurs with an emission maximum at 468 nm upon excitation at 397 nm.     

Boron‐Containing Protoporphyrin IX Derivatives and Their Modification for Boron Neutron Capture Therapy: Synthesis,Characterization, and Comparative In Vitro Toxicity Evaluation

A novel series of boronated porphyrins for potential use in boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) for tumor suppression is described. Protoporphyrin IX {i.e., bis(α‐methyl‐β‐pentylethylether)protoporphyrin IX, and bis(α‐methyl‐β‐dodecanylethylether)protoporphyrin IX} bearing polyhedral borane anions (B₁₂H₁₁SH^2?, B₁₂H₁₁NH₃^?, or B₁₂H₁₁OH^2?) were synthesized with reasonable yields. Modification of the protoporphyrin IX structure was achieved by variation of the lengths of the alkyl chains (pentyl and dodecanyl) attached through ether linkages to the former vinyl groups. The goal of this modification was to develop boronated porphyrins with chemical and physical properties that differed from those of protoporphyrin IX. Performance of an MTT assay with each derivative revealed that the synthesized boronated porphyrins showed low cytotoxicities in a variety of cancer cells. Of these compounds, B₁₂H₁₁NH₂^2?‐conjugated porphyrin induced a significant increase in the level of boron accumulation and PDT efficacy against HeLa cells.     

Potassium carbamoyldi­cyano­methanide

The crystal structure of the title compound, K[(CN)₂CC(O)NH₂)] or K⁺·C₄H₂N₃O⁻, conventionally abbreviated as Kcdm, where cdm is carbamoyldi­cyano­methanide, is described. The bond lengths and angles of the cdm cation are comparable to those reported previously for [M(cdm)₂(H₂O)₄]·2H₂O (M = Ni, Mn and Co). The K atoms are coordinated to four nitrile N atoms and two carbonyl O atoms in a distorted trigonal prismatic fashion, with two further N atoms semicoordinated through the centers of two prism side faces. This coordination leads to the formation of mixed anion–cation sheets parallel to the ab plane, which are joined together via hydrogen‐bonding interactions. The cdm anion is potentially useful for the formation of transition metal coordination polymers, in which magnetic superexchange could occur through a bidentate cdm bridge. Kcdm provides a model compound by which the molecular geometry of the cdm anion can be analyzed.     

Extensive Structural Rearrangements upon Reduction of 9H‐9‐Borafluorene

Common wisdom has it that organoboranes are readily oxidized. Described herein is that also their reduction can result in remarkable chemistry. Treatment of dimeric 9H‐9‐borafluorene with Li metal in toluene yields two strikingly different classes of compounds. One part of the sample reacts in a way similar to B₂H₆, thus affording an aryl(hydro)borane cluster reminiscent of the [B₃H₈]^? anion. The other part furnishes a dianionic boron‐doped graphene flake devoid of hydrogen substituents at the boron centers and featuring a central B?B bond. A change in the solvent to THF allows an isolation of this dibenzo[g,p]chrysene analogue in good yields.     

Derivatives of the closo-dodecaborate anion and their application in medicine

The paper presents a comparative analysis of the possibilities and characteristic features of the application of various polyhedral boron compounds, viz., the closo-decaborate anion [B₁₀H₁₀]^2–, the closo-dodecaborate anion [B₁₂H₁₂]^2–, the carba-closo-dodecaborate anion [CB₁₁H₁₂]^–, carboranes C₂B₁₀H₁₂, and the bis(dicarbollide) complexes [M(C₂B₉H₁₁)₂]^– (M = Fe, Co, or Ni), in boron neutron capture therapy (BNCT) for cancer. The requirements on compounds used in BNCT are formulated and the advantages of the application of the closo-dodecaborate anion are considered. The data on the synthesis of various derivatives of the closo-dodecaborate anion, which either already found use in BNCT or are most promising in this field, are summarized. The possibilities of the application of agents derived from the closo-dodecaborate anion in medical diagnostics are discussed.     

Darstellung und Kristallstrukturen von [P(C6H5)4][1-(NH3)B10H9] und Cs[(NH3)B12H11] · 2CH3OH

Synthesis and Crystal Structures of [P(C₆H₅)₄][1-(NH₃)B₁₀H₉] and Cs[(NH₃)B₁₂H₁₁] · 2CH₃OH The reduction of [1-(NO₂)B₁₀H₉]^2? with aluminum in alkaline solution yields [1-(NH₃)B₁₀H₉]^? and by treatment of [B₁₂H₁₂]^2? with hydroxylamine-O-sulfonic acid [(NH₃)B₁₂H₁₁]^? is formed. The crystal structures of [P(C₆H₅)₄][1-(NH₃)B₁₀H₉] (triclinic, space group P1 , a = 7.491(2), b = 13.341(2), c = 14.235(1) Å, α = 68.127(9), β = 81.85(2), γ = 86.860(3)°, Z = 2) and Cs[(NH₃)B₁₂H₁₁] · 2CH₃OH (monoclinic, space group P2₁/n, a = 14.570(2), b = 7.796(1), c = 15.076(2) Å, β = 111.801(8)°, Z = 4) reveal for both compounds the bonding of an ammine substituent to the cluster anion.     

A New Organic‐Inorganic Hybrid Copper Pentaborate with Free Boric Acid Group

The hydrothermal reaction of Cu(CH₃COO)₂·H₂O, H₃BO₃, ethylenediamine and H₂O in a molar ratio of 3:20:9:222 at 140°C for 5 d yields the deep blue crystals of a new copper polyborate [Cu(en)₂B(OH)₃]· [B₅O₅(OH)₇] (en?H₂NCH₂CH₂NH₂) in 70% yield. It crystallizes in monoclinic system, space group P2₁/c, with unit cell dimensions, a=1.2779(2) nm, b=1.0167(15) nm, c=1.5019(2) nm, β=90.30(2)°, Z=4. The crystal structure of this compound consists of [Cu(en)₂B(OH)₃]²⁺ cation and [B₅O₅(OH)₇]^2? anion, which are linked together through hydrogen bonding interactions and electrostatic forces, forming an interesting three‐dimensional framework. The [B₅O₅(OH)₇]^2? anion is constituted of [B₄O₅(OH)₄]^2? anion and discrete B(OH)₃ group which attaches to the side of [B₄O₅(OH)₄]^2? through intramolecular hydrogen bonds. Fundamental vibrational modes of this compound were identified and band assignments were made. The middle bands observed at 882 and 575 cm^?1 in Raman spectrum are the characteristic peak of B(OH)₃ group and [B₄O₅(OH)₄]^2? anion, respectively. Additionally the thermal behavior of title compound was recorded and its decomposition mechanism was discussed.     

nido‐Undecaboranes and ‐borates of the Type B11H13L and B11H12L‐

The Lewis base SMe₂ in 7‐B₁₁H₁₃(SMe₂) ( 1a ) can be replaced by the amines L = NH₂(CH₂tBu), NH₂Cy, NH₂Ph, NH₂(4‐C₆H₄Me), py, chinoline or the phosphanes L = PPh₃, PMePh₂, yielding 7‐B₁₁H₁₃L ( 1b ‐ i ). The borane 1a can be deprotonated by certain amines, alkanides, or hydrides to give the anion 7‐B₁₁H₁₂(SMe₂)^‐ ( 2a ). Replacing the base SMe₂ in the anion 2a by weak bases gives B₁₁H₁₂L^‐ (L = PPh₃, MeCN; 2h , j ). Upon reaction of 1a with the amine NH₂(CH₂tBu) in the ratio 1:2, a deprotonation and the substitution of SMe₂ by the amine are observed, 7‐B₁₁H₁₂[NH₂(CH₂tBu)]^‐ ( 2b ) being formed. At 170 °C, the 7‐isomers 1b , f are isomerized into a mixture of the corresponding 1‐ and 2‐isomers ( 1b′ , f′ and 1b″ , f″ , respectively).     

Aqua(n‐hexyl)[3,3′‐(propane‐1,3‐diyldinitrilo)­bis­(butan‐2‐one) dioximato‐­κ4N]cobalt(III) perchlorate

The title compound, [Co(C₆H₁₃)(C₁₁H₁₉N₄O₂)(H₂O)]ClO₄, is in the general class of coenzyme B₁₂ models which contain a ClO₄ anion and a [Co(C₆H₁₃)(C₁₁H₁₉N₄O₂)(H₂O)]⁺ cation. In the cation, the Co atom has a distorted octahedral coordination, with the n‐hexyl and H₂O ligands in axial positions. The crystal data reveal some degree of flexibility in the Costa‐type system, which is similar to the coenzyme B₁₂.     

Dodecahydro-<Emphasis Type="Italic">closo</Emphasis>-dodecaborate anion intercalation into graphite oxide

It is demonstrated by X-ray diffraction that, in the case of dodecahydro-closo-dodecaborates with small cations (H⁺, Li⁺, Na⁺, K⁺, NH ₄ ⁺ ), the intercalation of the B₁₂H ₁₂ ^2? anion into the interlayer space of graphite oxide is more favorable than the crystallization of a free salt. In the case of large cations commensurable with B₁₂H ₁₂ ^2? (e.g., Cs⁺), no intercalation takes place because these cations and the dodecaborate-closo-dodecaborate anion form stable cubic crystals as a separate phase outside the graphite oxide structure.     

Bismuth Undecahydro‐closo‐dodecaborane: A Retainable Intermediate of B−H Bond Activation by Bismuth(III) Cations

The [B₁₂H₁₂]^2? anion shows an extensive substitutional chemistry based on its three‐dimensional aromaticity. The replacement of functional groups can be attained by electrophilically induced substitution caused by Brønsted or Lewis acidic electrophiles (e.g. Pt²⁺). Until now, it was impossible to structurally characterize a metal‐substituted [B₁₂H₁₂]^2? cage. When an aqueous solution containing both Bi³⁺ cations and [B₁₂H₁₂]^2? anions was heated, the charge‐neutral bismuth undecahydro‐closo‐dodecaborane BiB₁₂H₁₁ was obtained, representing a new class of metalated [B₁₂H₁₂]^2? clusters. The title compound was characterized by single‐crystal X‐ray diffraction and NMR spectroscopic methods. Compared to the typical B?H bond, the short B?Bi single bond (230 pm) exhibits inverted polarity.     

Propane‐1,3‐diaminium tetrachloridozincate(II) 18‐crown‐6 clathrate

The reaction of propane‐1,3‐diamine hydrochloride, 18‐crown‐6 and zinc(II) chloride in methanol solution yields the title complex salt [systematic name: propane‐1,3‐diaminium tetrachloridozincate(II)–1,4,7,10,13,16‐hexaoxacyclooctadecane (1/1)], (C₃H₁₂N₂)[ZnCl₄]·C₁₂H₂₄O₆, with an unusual supramolecular structure. The diprotonated propane‐1,3‐diaminium cation forms an unexpected 1:1 supramolecular rotator–stator complex with the crown ether, viz. [C₃H₁₂N₂(18‐crown‐6)]²⁺, in which one of the –NH₃⁺ substituents nests in the crown and interacts through N—H...O hydrogen bonding. The other –NH₃⁺ group interacts with the [ZnCl₄]²⁻ anion via N—H...Cl hydrogen bonding, forming cation–crown–anion ribbons parallel to [010].     

Isoamyl­cobalamin–acetone–water (1/0.385/12.650)

The title compound, [Co(C₅H₁₁)(C₆₂H₈₈N₁₃O₁₄P)]·0.385C₃H₆O·12.650H₂O, contains the isoamyl (3‐methyl­butyl) anion bonded to the Co^III ion through a C atom. The compound is thus a structural analog of the two biologically important vitamin B₁₂ coenzymes adenosyl­cobalamin and methyl­cobalamin. The lower axial Co—N bond length [2.277 (2) Å] is one of the longest ever reported for a cobalamin and reflects the strong σ‐donor ability of the isoamyl group.     

硼化合物研究——ⅩⅪ.H[B12H11NH2COR]与Ln2O3的反应——一类新型的含硼希土(Ⅲ)化合物的合成

将硼烷衍生物(C_2H_5)_4NB_(12)H_(11)NH_2COR[R=-CH-3,—CH=CH_2]经离子交换而得到的酸H[B_(12)H_(11)NH_2COR]与希土氧化物作用,制得一系列分子式为L-n[B_(12)H_(11)NH_2COR]_3·5H_2O的化合物,再用氧化吡啶(pyO)与上述化合物反应,就得到了分子式为[Ln(pyO)_6](B_(12)H_(11)NH_2COR)_3的新型化合物。     

Supramolecular networks supported by the anion…π linkage of Keggin‐type heteropolyoxotungstates

Anion…π interactions are newly recognized weak supramolecular forces which are relevant to many types of electron‐deficient aromatic substrates. Being less competitive with respect to conventional hydrogen bonding, anion…π interactions are only rarely considered as a crystal‐structure‐defining factor. Their significance dramatically increases for polyoxometalate (POM) species, which offer extended oxide surfaces for maintaining dense aromatic/inorganic stacks. The structures of tetrakis(caffeinium) μ₁₂‐silicato‐tetracosa‐μ₂‐oxido‐dodecaoxidododecatungsten trihydrate, (C₈H₁₁N₄O₂)₄[SiW₁₂O₄₀]·3H₂O, (1), and tris(theobrominium) μ₁₂‐phosphato‐tetracosa‐μ₂‐oxido‐dodecaoxidododecatungsten ethanol sesquisolvate, (C₇H₉N₄O₂)₃[PW₁₂O₄₀]·1.5C₂H₅OH, (2), support the utility of anion…π interactions as a special kind of supramolecular synthon controlling the structures of ionic lattices. Both caffeinium [(HCaf)⁺ in (1)] and theobrominium cations [(HTbr)⁺ in (2)] reveal double stacking patterns at both axial sides of the aromatic frameworks, leading to the generation of anion…π…anion bridges. The latter provide the rare face‐to‐face linkage of the anions. In (1), every square face of the metal–oxide cuboctahedra accepts the interaction and the above bridges yield flat square nets, i.e. {(HCaf⁺)₂[SiW₁₂O₄₀]^4?}_n. Two additional cations afford single stacks only and they terminate the connectivity. Salt (2) retains a two‐dimensional (2D) motif of square nets, with anion…π…anion bridges involving two of the three (HTbr)⁺ cations. The remaining cations complete a fivefold anion…π environment of [PW₁₂O₄₀]^3?, acting as terminal groups. This single anion…π interaction is influenced by the specific pairing of (HTbr)⁺ cations by double amide‐to‐amide hydrogen bonding. Nevertheless, invariable 2D patterns in (1) and (2) suggest the dominant role of anion…π interactions as the structure‐governing factor, which is applicable to the construction of noncovalent linkages involving Keggin‐type oxometalates.     

Thermal transformations of B10H12(NH3)2, B10H12(C5H5N)2, and B10H12(C9H7N)2

Conclusions For B₁₀H₁₂L₂, where L=NH₃, C₅H₅N, or C₉H₇N, features of thermal transformations in the range 25–850°C and the composition of the pyrolysis products are determined. The latter are x-ray amorphous phases, containing nitride, carbide, boron carbide, boron, and carbon.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2481–2484, November, 1988.     

Intermolecular dihydrogen‐ and hydrogen‐bonding interactions in diammonium closo‐decahydrodecaborate sesquihydrate

The asymmetric unit of the title salt, 2NH₄⁺·B₁₀H₁₀²⁻·1.5H₂O or (NH₄)₂B₁₀H₁₀·1.5H₂O, (I), contains two B₁₀H₁₀²⁻ anions, four NH₄⁺ cations and three water molecules. (I) was converted to the anhydrous compound (NH₄)₂B₁₀H₁₀, (II), by heating to 343 K and its X‐ray powder pattern was obtained. The extended structure of (I) shows two types of hydrogen‐bonding interactions (N—H...O and O—H...O) and two types of dihydrogen‐bonding interactions (N—H...H—B and O—H...H—B). The N—H...H—B dihydrogen bonding forms a two‐dimensional sheet structure, and hydrogen bonding (N—H...O and O—H...O) and O—H...H—B dihydrogen bonding link the respective sheets to form a three‐dimensional polymeric network structure. Compound (II) has been shown to form a polymer with the accompanying loss of H₂ at a faster rate than (NH₄)₂B₁₂H₁₂ and we believe that this is due to the stronger dihydrogen‐bonding interactions shown in the hydrate (I).     

Ammonium O,O‐dicyclo­hexyl phosphoro­dithio­ate

The structure of the title compound, NH₄⁺·C₁₂H₂₂O₂PS₂⁻, consists of a polymeric arrangement of ammonium cations and O,O‐dicyclohexyl phosphorodithioate anions linked through N—H⋯O and N—H⋯S hydrogen bonds. These inter­actions result in the formation of (100) sheets.