Protonation of the Dodecahydro-<Emphasis Type="Italic">closo</Emphasis>-Dodecaborate Anion in CH<Subscript>3</Subscript>CN/CF<Subscript>3</Subscript>COOH

The behavior of the [B₁₂H₁₂]^2– anion in CH₃CN, CF₃COOH, and the CH₃CN/CF₃COOH system is studied by IR spectroscopy. Based on the IR spectroscopy data correlated with the data obtained when studying the protonation processes of boron cluster anions [B₆H₆]^2– and [B₁₀H₁₀]^2–, the possibility to prepare the protonated form of the closo-dodecaborate anion, namely monoanion [B₁₂H₁₃]^–, is concluded in CF₃COOH and the CH₃CN/CF₃COOH system. In the IR spectra of salts of the protonated forms of anions [B_nH_n]^2– (n = 6, 10, 12) in solutions and Nujol mulls, a high-frequency shift of the ν(BH) absorption bands is observed as compared with the spectra of salts of non-protonated anions Cat₂[B_nH_n] (Δν = 70–100 cm^–1).     

<Emphasis Type="Italic">N</Emphasis>-trifluoroacetyl-β-alanine in the synthesis of carnosine

Conditions have been developed for the synthesis of N-trifluoroacetyl-β-alanine, N-tifluoroacetyl-β-alanyl chloride, and N-trifluoroacetyl-β-alanine 4-nitrophenyl ester. These compounds reacted with histidine methyl ester or sodium salt to give N-trifluoroacetyl-β-alanyl-l-histidine methyl ester CF₃CONHCH₂CH₂·CONHCH(CH₂C₃H₃N₂)COOCH₃ and N-trifluoroacetyl-β-alanyl-l-histidine CF₃CONHCH₂CH₂CONHCH·(CH₂C₃H₃N₂)COOH. Their hydrolysis with a solution of sodium hydroxide in aqueous ethanol, followed by acidification with trifluoroacetic acid, led to the formation of β-alanyl-l-histidine (l-carnosine).     

Double helix of the coordination polymer of silver with 1,3-bis(4-pyridyl)propane: Synthesis and crystal structure of [Ag(C<Subscript>13</Subscript>H<Subscript>14</Subscript>N<Subscript>2</Subscript>)](CF<Subscript>3</Subscript>CO<Subscript>2</Subscript>)

The [Ag(Bpp)](CF₃CO₂) complex (Bpp is 1,3-bis(4-pyridyl)propane, C₁₃H₁₄N₂) is synthesized, and its structure is determined. The crystals are monoclinic, space group C2/c, a = 26.169(5), b = 10.521(2), c = 12.906(3) Å, β = 117.99(3)°, V = 3137.7(11) ų, ρ_calcd = 1.775 g/cm³, Z = 8. The structure contains double helices of-Ag-Bpp-Ag-Bpp-cationic chains with a helix period of 21.042 Å. The Ag…Ag distance between a pair of silver atoms from different chains in the helix is 3.201 Å, and the distance between the adjacent helices is 3.279 Å. The silver atom is linked with two bridging nitrogen atoms of two Bpp ligands in an almost linear coordination: Ag-N_avg 2.142 Å; NagN, 171.3(4)°. The CF₃C ₂ ^? anion has a weak contact with the silver ion (Ag…O 2.62(2) Å).     

<Emphasis Type="Italic">N,N</Emphasis>-diethylanilinium complex with borodicitric acid: Synthesis and crystal structure

N,N-Diethylanilinium dicitratoborate [C₆H₅NH(C₂H₅)₂][(C₆H₆O₇)₂B] (I) has been synthesized for the first time. Single crystals has been synthesized in an aqueous solution to study the crystal structure of complex I by single-crystal X-ray diffraction. Crystals are triclinic, space group Р1 a = 9.6183(2) Å, b = 10.3153(3) Å, c = 13.7364(4) Å, α = 69.0304(12)°, β = 77.0394(13)°, γ = 89.5518(10)°, V = 1236.25(6) ų, Z = 2, ρ_calcd = 1.454 g/cm³. Structural units in a crystal of complex I are large complex dicitratoborate anions with a spirane structure and N,N-diethylanilinium cations. The crystal packing is a three-dimensional framework implemented via a system of hydrogen bonds like О–Н…О, О–Н…О, ОI, and N–Н…О.     

A novel bimetallic chain based on [Mo(Cn)<Subscript>8</Subscript>]<Superscript>3−</Superscript> and Eu<Superscript>3+</Superscript> ions as building blocks

A novel Mo^V-Eu^III bimetallic chain, {[Eu^III(Phen)(DMF)₄][Mo^V(CN)₈] · i-C₃H₇OH · 3H₂O} _n (I) (DMF = N,N′-dimethylformamide; Phen = phenanthroline), has been constructed by the reaction of [Mo(CN)₈]^3? with Eu³⁺ and phenanthroline in mixed solvent DMF/i-C₃H₇OH. Complex I is confirmed as a chain structure by X-ray structural analysis. The neighboring chains interact with each other by one type of face-to-face π…π stack with the distance of 3.5522(10) Å. Thus complex I has been extended to a 2D network.     

Derivatives of α,β-dehydroamino acids: V. Intramolecular cyclization of 2-{2-[(<Emphasis Type="Italic">Z</Emphasis>)-1-Benzamido-2-phenylvinyl]acetamidomethyl}benzimidazole

Reaction of 4-benzylidene-2-phenyl-1,3-oxazol-5(4H)-one with 2-(1H-benzimidazol-2-yl)ethaneamine led to the formation of 2-{2-[(Z)-1-benzamido-2-phenylvinyl]acetamidomethyl}benzimidazole that in a reaction with hexamethyldisilazane in DMF gave 5-benzylidene-1-(1H-benzimidazol-2-yl)-2-phenyl-3,5-dihydro-4H-imidazol-4-one. In the presence of K₂CO₃ in dioxane the reaction with hexamethyldisilazane resulted in the product of intramolecular addition, N-(4-benzyl-3-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]-benzimidazol-4-yl)benzamide     

Processes of hydrogenation of trifluoromethylfullerenes in the mass spectrometer ion source

The processes of hydrogenation of a mixture of trifluoromethylfullerenes was studied in situ by means of positive-and negative-ion mass spectrometry. The effective addition of 1, 5, and 11 hydrogen atoms was revealed. The appearance energies of positive trifluoromethylfullerene ions C ₆₀ (CF₃) _n ⁺ (n = 1–8) and C₆₀(CF₃) _n H⁺ (n = 1, 3, 5, 7) were determined.     

Hexafluorosilicates of cobalt(II) complexes with dimethylsulfoxide and dimethylformamide

New double complexes [Co(DMSO)₆][SiF₆] ? 2H₂O (I) and [Co(DMF)₃(H₂O)₃][SiF₆] ? DMF (II) have been synthesized and studied by IR spectroscopy and X-ray diffraction. Crystals of complex I belong to the tetragonal symmetry system, space group R3?, Z = 3, a = 11.8232(3) Å, c = 18.4699(5) Å, V = 2235.97(10) ų, ρ_calc = 1.573 g/cm³. Crystals of complex II are triclinic, space group P1?, Z = 2, a = 8.6264(4) Å, b = 10.1419(4) Å, c = 13.9657(6) Å, α = 100.847(2)°, β = 98.549(2)°, γ = 93.479(2)°, V = 1181.71(9) ų, ρ_calc = 1.539 g/cm³.     

Structural characterisation and photoluminescence of a pyridine–diimine compound

A pyridine–diimine compound N,N′-[pyridine-2,6-diyldi(E)methylylidene]bis(4-chloroaniline) is synthesised by a Schiff base condensation of 2,6-diformylpyridine with 4-chloroaniline in methanol and characterised by spectroscopic and analytical techniques. The molecular structure of the compound is determined by the single crystal X-ray diffraction study. The compound crystallizes in the monoclinic crystal system, I2/c space group with unit cell parameters a = 7.0843(12) Å, b = 6.1909(11) Å, c = 36.262(6) Å, β = 91.576(3)°, V = 1589.8(5) ų and Z = 4. There is an intermolecular hydrogen bonding in the molecule resulting in a 1D hydrogen bonding chain and these hydrogen bonding chains are linked by Cl…HC(aromatic) interactions forming a 2D network. Crystal packing of the compound is determined by Cl…HC and π–π interactions. In the fluorescence emission spectra in CH₃CN, DMF, DMSO and EtOH, the compound shows only one emission maximum.     

Structure of arsenic 8-mercaptoquinolinate: Synthesis and crystal structure of arsenic 4-methoxy-8-mercaptoquinolinate As[C<Subscript>9</Subscript>H<Subscript>5</Subscript>(OCH<Subscript>3</Subscript>)NS]<Subscript>3</Subscript>

Arsenic 4-methoxy-8-mercaptoquinolinate As[C₉H₅(4-OCH₃)NS]₃ (I) was synthesized and studied by X-ray diffraction. Crystals are trigonal: space group R3, a = b = 13.9867(4) Å, c = 12.4991(5) Å, γ = 120°, V = 2117.58(12) ų, ρ = 1.519 g/cm³, Z = 3. An arsenic atom in the crystal structure occupies a special position on axis 3. The structural unit of the crystal (neutral complex I) has symmetry C3. 4-Methoxy-8-mercaptoquinoline acts as a bidentate (N,S-) ligand. The coordination polyhedron of the arsenic atom is a symmetric octahedron (3S + 3N) or, with allowance for the lone electron pair, ψ-one-capped octahedron (3S + 3N + E). Bond lengths are as follows: As-S, 2.3179(7)Å; As…N 2.688(3) Å. The geometries of coordination polyhedra of arsenic atoms are compared in the crystal structures of As(C₉H₆NS)₃, As[C₉H₅(2-CH₃)NS]₃, and As[C₉H₅(4-CH₃)NS]₃.     

Thermodynamic and kinetic stability of cerium(IV) complexes with a series of aminopolyacetic acids

The compositions, stability constants, and rate constants of intramolecular redox decomposition of cerium(IV) complexes with anions of aminoacetic (H₂NCH₂COOH), iminodiacetic [HN(CH₂COOH)₂], nitrilotriacetic [N(CH₂COOH)₃], ethylenediaminetetraacetic [(CH₂COOH)₂N(CH₂)₂N(CH₂COOH)₂], and hexamethylenediaminetetraacetic [(CH₂COOH)₂N(CH₂)₆N(CH2COOH)₂] acids were determined by potentiometric, spectrophotometric, and kinetic methods at pH in the range 1.3?2.0 in perchlorate and nitrate media at an ionic strength I = 0.1 and a temperature of 298.15 K. Direct linear correlation between the logarithms of the stability constants of the complexes, log β₁₀₁, and logarithms of the cumulative protonation constants, log В _m+k (k = 1–2), of aminopolyacetic acid anions L ^m–, and inverse linear correlation between log β₁₀₁ and logarithms of the rate constants of intramolecular redox decomposition of the complexonates [CeL]^4–m (m = 1–4), log k _n=1, were found.     

[H<Subscript>2</Subscript>OT][PdCl<Subscript>4</Subscript>], a salt of the protonated oxythiamine cation with the tetrachloropalladate(II) tetrachloride anion synthesis and crystal structure

The interaction of oxythiamine chloride hydrochloride with a solution of palladium chloride in hydrochloric acid affords a salt of protonated oxythiamine [H₂OT][PdCl₄] (I) (HOT is 4-methyl-3-[(2′-methyl-4′-oxo-3′,4′-dihydropyrimidinyl-5′)methyl]-5-(2-hydroxyethyl)thiazolium, C₁₂H₁₆N₃O₂S⁺). The crystal structure of salt I is determined by X-ray diffraction analysis. The crystals are monoclinic: a = 9.474(3) Å, b = 13.822(2) Å, c = 13.626(4) Å, β = 93.42(2)°, V = 1781.2(3) ų, Z = 4, space group P2₁/n. The structural units of salt I are doubly-charged cations [H₂OT]²⁺ and anions [PdCl₄]^2? joined by hydrogen bonds and electrostatic interaction into dimeric supermolecules. The thiazolium and pyrimidine rings in the cation are planar (the dihedral angle between the planes is 89.6°) and oriented relative to the linking methylene center to form torsion angles Φ _t = 64.9° and Φ _p = 49.9° characteristic of the V′ conformation.     

A restudy of the crystal structure of tetraaquastrontium dicitratoborate trihydrate

The crystal structure of Sr(H₂O)₄[(C₁₂H₁₁O₁₄)B] · 3H₂O (I) has been restudied and determined with a higher accuracy. The crystals are monoclinic, space group P2₁/n, a = 11.405(1) Å, b = 18.814(1) Å, c = 11.987(1) Å, β = 110.79(1)°; Z = 4. The structure was refined by full matrix least-squares calculation to R = 0.0547 on 5343 unique reflections with R _int = 0.0419. The structural units of crystal I are the Sr²⁺ cation, seven water molecules, and doubly charged dicitratoborate anion, which is not equivalent to the singly charged complex dicitratoborate anion identified previously in the crystal structures of complexes of boric and citric acids. The coordination polyhedron of the Sr²⁺ cation is a distorted dodecahedron composed of four O atoms of coordinated water molecules and four O atoms of two complex anions. The crystal packing of I is layered. Thirteen independent O-H…O and O-H…, O′ contacts form an intricate system of hydrogen bonds.     

Synthesis and crystal structure of dimethylgold(III) carboxylates

Three novel carboxylate complexes were synthesized: dimethylgold(III) trifluoroacetate [Me₂Au(Tfa)]₂ (I), trimethylacetate (pivalate) [Me₂Au(Piv)]₂ (II), and benzoate [Me₂Au(OBz)]₂ (III). The starting reagent was [Me₂AuI]₂. The procedure of its synthesis provides 60% product yield. Dimethylgold(III) carboxylates were identified from the IR and ¹H NMR data. The title compounds were studied by X-ray diffraction. The unit cell parameters for I, C₈H₁₂Au₂F₆O₄: a = 15.5522(13), b = 12.9398(11), c = 15.6555(14) Å, β = 104.308(2)°, Z = 8, ρ(calcd.) = 2.959 g/cm³, space group C2/c, R = 0.0779; for II, C₁₄H₃₀Au₂O₄: a = 10.3025(3), b = 15.5952(4), c = 12.6819(3) Å, β = 105.8270(10)°, Z = 4, ρ(calcd.) = 2.224 g/cm³, space group P2₁/c, R = 0.0229; for III, C₁₈H₂₂Au₂O₄: a = 12.8050(2), b = 19.7886(3), c = 7.60300(10) Å, Z = 4, ρ(calcd.) = 2.401 g/cm³, space group Pnma, R = 0.0144. Compounds I–III have the molecular structures; the structural units are the [(CH₃)₂Au(OOCR)]₂ dimers (Au…Au 2.984–3.080 Å), R = CF₃, tert-Bu, Ph. The gold atoms have the square coordination with two carbon atoms and two oxygen atoms (Au-O 2.120–2.173 Å). The molecules in compounds I–III are united into infinite unidimensional chains connected by van der Waals interactions.     

Crystal structure and thermodynamic stability of an acetone solvate of bis(trifluoroacetylacetonato)copper(II)

A solvate [Cu(CF₃COCHCOCH₃)₂(CH₃COCH₃)] has been synthesized and characterized for the first time. According to X-ray structural data (diffractometer X8 APEX BRUKER, radiation MoK _α, T = 150 K), it crystallizes in the monoclinic crystal system, space group P2₁/c, a = 8.9940(4) Å, b = 22.3966(11) Å, c = 8.1884(3) Å, β = 92.705(2)°, V = 1647.59(12) ų, Z = 4, d _calc = 1.725 g/cm³, final R = 0.0272. The structure is molecular. In the equatorial plane the atom Cu(II) is surrounded with four oxygen atoms of two chelating ligands (CF₃COCHCOCH₃)^?; Cu-O distances 1.927–1.937 Å, O-Cu-O angles 86.18–93.30° and 170.18–175.67°. Square coordination of Cu is complemented to the square-pyramidal one by the oxygen atom of an acetone molecule behaving as an axial ligand; Cu-O_acetone 2.342 Å, O-Cu-O_acetone 89.66–100.11°. In the studied compound disorder of one of the chelate ligands implies the co-existance of the molecules in the cis- and trans-configuration in the crystal under ratio 54.6:45.4. In air the solvate rapidly degrades losing acetone, while in a sealed vessel melts around 313 K. Temperature dependence of equilibrium vapor pressure of acetone over the complex was measured with the static spoon gauge technique, thermodynamic characteristics of its dissociation process being derived: [Cu(CF₃COCHCOCH₃)₂(CH₃COCH₃)]_s = [Cu(CF₃COCHCOCH₃)₂]_s + CH₃COCH_3g, ΔH _av ⁰ = 49.6(3) kJ/mol, ΔS _av ⁰ = 152(1) J/(mol K), ΔG _av ⁰ = 4.30(2) kJ/mol.     

Synthesis and crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane bis[dichloro(thiocyanato)copper(II)]

A new complex salt [4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane bis[dichloro(thiocyanato)copper(II)], [H₂(Crypt-222)][CuCl₂(SCN)]₂, is synthesized and studied by X-ray diffraction analysis. The crystals are monoclinic (space group C2/c, a = 14.603 Å, b = 8.330 Å, c = 25.091 Å, β = 100.76°, Z = 4). The structure is solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.047 for 2943 independent reflections (CAD-4 automated diffractometer, λMoK _α radiation). The Cu²⁺ cations and Cl^? and SCN^? anions form infinite polymeric chains of spiro-conjugated alternating centrosymmetric four-membered CuCl₂Cu cycles and eight-membered Cu(SCN)₂Cu cycles through coordination bonds. The coordination polyhedron of the Cu²⁺ cation is a distorted trigonal bipyramid. The [H₂(Crypt-222)]²⁺ dication contains trifurcate N⁺-(…O)₃ bonds on axis 2.     

<Emphasis Type="Italic">trans</Emphasis>-Tetraaqua(dibromo)nickel(II) 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane dibromide: Synthesis and crystal structure

A new complex, trans-tetraaqua(dibromo)nickel(II) 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane dibromide, [NiBr₂(H₂O)₄][H₂(Crypt-222)]Br₂ (I), was synthesized and its crystal sructure was studied by X-ray diffraction analysis: space group P2₁/c, a = 13.573, b = 8.328, c = 14.523 Å, β = 111.08°, Z = 2. Structure I was solved by a direct method and refined by full-matrix least-squares method in anisotropic approximation to R = 0.067 on 2684 independent reflections (CAD-4 autodiffractometer, λMoKα). The octahedral complex molecule [NiBr₂(H₂O)₄] and the [H₂(Crypt-222)]²⁺ dication (with two protonated N atoms) are located around the inversion center; the latter is statistically disordered. The dication contains trifurcate hydrogen bonds N-H(…O)₃. Crystal I also contains intermolecular hydrogen bonds O(w)-H…Br^?, which join the complex molecules [NiBr₂(H₂O)₄] and the Br^? anions into infinite “thick” layers parallel to the plane yz.     

Ribbon structure of the coordination polymer of silver trifluoroacetate with 2-pyrimidinecarboxamide

Complex [Ag(CF₃CO₂)(C₅H₅N₃O)] (I) was synthesized, and its structure was determined. Crystals of complex I are triclinic, space group P \(\bar 1\),,a = 7.325(1) Å, b = 7.554(1) Å, c = 10.527(1) Å, α = 94.25(1)°, β = 96.19(1)°, γ = 117.75(1)°, V = 507.4(1) ų, ρ_calcd = 2.252 g/cm³, Z = 2. Structure I contains dimeric silver carboxylates Ag₂(C₅H₅N₃O) ₂ ²⁺ , formed by 2-pyrimidinecarboxamide. Adjacent dimers Ag₂(C₅H₅N₃O) ₂ ²⁺ are linked by carboxylate dimers to form infinite ribbons along the x axis. The ribbons are arranged in the structure so that cavities are formed between them in the [001] direction. Trifluoroacetate CF₃ groups and carboxamide NH₂ groups are directed into the inside of these cavities.     

Protonation of 3-Arylpropynoic Acid Derivatives in Superacids

According to the ¹H and ¹³C NMR data, 3-arylpropynoic acids and their esters XC₆H _n -C≡C-CO₂R (R = H, Me, Et) having electron-withdrawing substituents in the benzene ring (X = NO₂, CN, COMe, CO₂Me) exist in HSO₃F at ?80 to 0°C as XC₆H _n -C≡C-C⁺(OH)OR ions. Derivatives with other substituents (X = H, F, Me, MeO) in HSO₃F or CF₃SO₃H above ?40°C undergo protonation at the acetylenic carbon atom neighboring to the acid group to give unstable vinyl-type XC₆H _n -C⁺=CH-CO₂R cations which are then transformed into mixtures of stereoisomeric (Z and E) fluorosulfonates or triflluoromethanesulfonates XC₆H _n -CY=CH-CO₂R (Y = OSO₂F, OSO₂CF₃), the E isomer prevailing.