Complexes of sodium and lithium borohydrides with macrocyclic polyethers

A method for the synthesis of complexes of sodium and lithium borohydrides with crown ethers is proposed. The complexes of sodium borohydride with benzo-15-crown-5, 4′-aminobenzo-15-crown-5, dibenzo-18-crown-6, and diaza-18-crown-6 and the complexes of lithium borohydride with benzo-15-crown-5 and dibenzo-18-crown-6 are synthesized. These complexes can be used for the preparation of hydrogen in their reactions with methanol. The complex formation does not affect the purity of hydrogen formed.     

Synthesis of Schiff bases and benzylamino derivatives containing [1-B<Subscript>10</Subscript>H<Subscript>9</Subscript>NH<Subscript>3</Subscript>]<Superscript>−</Superscript> anion

Reactions of an amino derivative of the closo-decaborate anion [1-B₁₀H₉NH₃]^– with aromatic aldehydes afforded Schiff bases [1-B₁₀H₉NH=CHAr]^– (Ar=Ph, C₆H₄-2-OMe, or C₆H₄-4-NHCOMe). The reduction of the latter with sodium borohydride gave the corresponding benzylamino derivatives [1-B₁₀H₉NH₂CH₂Ar]^–.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2004–2007, September, 2004.     

Oxonium derivatives of <Emphasis Type="Italic">closo</Emphasis>-decaborate in reactions with sulfur-containing nucleophiles

The reaction of the [B₁₀H₉O₂C₄H₈]⁻, [B₁₀H₉OC₄H₈]⁻, and [B₁₀H₉OC₅H₁₀]⁻ anions with negatively charged S-nucleophiles, such as SH⁻, SCN⁻, and S₂O₃ ²⁻, resulted in the ring opening of the cyclic substituent and the formation of derivatives with the terminal thiol, thiocyanate, and thiosulfate groups. The structures of the products were confirmed by the IR, mass, and ¹H, ¹¹B, and ¹³C NMR spectra.     

Isomerization [trans-B20H18]2– → [iso-B20H18]2– during silver(I) complexation with triphenylphosphine

The trans–iso isomerization of the dimeric borohydride cluster anion [B₂₀H₁₈]^2– in the course of the silver(I) complexation reaction with triphenylphosphine has been described for the first time. The isomeric complexes [Ag₂(Ph₃P)₆[trans-B₂₀H₁₈]] and [Ag₂(Ph₃P)₆[iso-B₂₀H₁₈]] have been isolated and characterized by physicochemical methods. The structures of the compounds have been determined by X-ray crystallography.     

On the limitation of the term <Emphasis Type="Italic">petroleum products</Emphasis> in the determination of the oil pollution of bottom sediments

Problems related to the determination of the oil pollution of bottom sediments are discussed. Tarry substances resistant to degradation, whose content can be as high as 50% on a total oil basis, are accumulated in the bottom sediments. The conventional term petroleum products, which implies only a hydrocarbon fraction, does not adequately describe these substances; because of this, the really evaluated level of the oil pollution of bottom sediments becomes underestimated to a considerable degree. We proposed to determine tarry substances in bottom sediments by fluorescence spectrometry at 490–510 nm in combination with a stage of the chromatographic preconcentration and separation of oils and petroleum products into the following main group components: hydrocarbons, tars, and asphaltenes. The substances coextracted with the petroleum products (pesticides, phenols, pigments, etc.) occurred in a chromatographic zone of tars and asphaltenes, but they fluoresce at other wavelengths and do not interfere with the determination. The typical chromatograms of hydrocarbons from the bottom sediments of different water bodies obtained by gas chromatography are given.     

Copper(I) coordination compounds with closo-dodecaborate anion

Copper(I) complexes with a closo-dodecaborate anion were synthesized: Cat[CuB₁₂H₁₂], where Cat = Cs⁺, Ph₄P⁺, Ph₄As⁺, or R _x NH _4?x ⁺ (R = Me, Et, Pr, or Bu; x = 3 or 4). The complexes were synthesized from the copper(II)-closo-dodecaborate-sulfur dioxide (sodium sulfite) system. The structure of [Cu₂(NCCH₃)₄B₁₂H₁₂] was determined using X-ray crystallography.     

Low-temperature heat capacity and thermal behavior of Zn<Subscript>0.98</Subscript>Co<Subscript>0.02</Subscript>O in the high-temperature region

The low-temperature heat capacity of Zn _0.98Co_0.02O oxide was measured by adiabatic calorimetry. The formation of a solid solution was shown to be accompanied by a change in the entropy by 0.4 J/(K mol). No anomalies in the heat capacity or the thermal behavior confirming the phase transformations found earlier by other methods were observed. A heat capacity anomaly was revealed below 15 K and tentatively attributed to a change in the magnetic properties of the substance.     

Compounds of Undecahydrodecaborate Anion B10H11–

Conditions for the synthesis of salts of the B₁₀H₁₁ ^–anion with different cations in the Cat₂B₁₀H₁₀+ RCOOH (R = H, CF₃; Cat = Me₄N⁺, Et₄N⁺, Bu₄N⁺, Ph₄P⁺, Ph₄As⁺) systems were studied depending on the acid strength (pK _a) and size of the cation. It was established that reactions with trifluoroacetic acid give compounds of this anion with any one of the quaternary ammonium, phosphonium, or arsonium cations, while formic acid can only give salts with the largest of these cations.     

A new preparative method for the synthesis of oxonium derivatives of the decahydro-<Emphasis Type="Italic">closo</Emphasis>-decaborate anion

A new method for the synthesis of oxonium derivatives of the closo-decaborate anion in high yields was described. Reactions of the anion B₁₀H₁₀ ²⁻ with cyclic ethers (tetrahydrofuran (THF) and tetrahydropyran) in the presence of dry HCl are stepwise processes. Depending on the reaction temperature and time, either mono- or disubstituted products were obtained. Their structures were determined using ¹¹B, ¹³C, and ¹H NMR and IR spectroscopy, ESI mass spectrometry, and elemental analysis for boron.     

Nickel(II) complexes with nitrogen-containing derivatives of the closo-decaborate anion

The reactions of the salt (Bu₄N)[2-B₁₀H₉O₂C₄H₈] (1) with ammonia and ethylenediamine in ethanol were studied. These reactions afford substituted closo-decaborates with nitrogencontaining groups linked to the cluster through a diethylene glycol spacer. Using this method, we synthesized derivatives of the closo-decaborate anion with the pendant groups -NH₃ ⁺ and -NHCH₂CH₂NH₂; the complexes [Ni(H₂O)(en)(L)] (7) and [Ni(en)(L)]·0.5H₂O (8), where L = [2-B₁₀H₉O(CH₂)₂O(CH₂)₂NH(CH₂)₂NH₂]^2?, were synthesized. The X-ray diffraction study showed that the coordination sphere of the Ni²⁺ ions in complexes 7 and 8 have the same composition (4 N + 2 O). However, the coordination environment differs in the nature of the oxygen atom. Thus the oxygen atom directly bonded to the boron cluster is involved in the coordination of the metal ion in compound 8, whereas a water molecule is involved in the coordination in compound 7.