DFT-calculated structure of protonated tetraphenyl p - tert -butylcalix[4]arene tetraketone

Using DFT calculations, two of the most probable structures (A, B) of the tetraphenyl p-tert-butylcalix[4]arene tetraketone·H₃O⁺ cationic complex species were derived. The hydroxonium ion H₃O⁺, placed in the coordination cavity formed by the calix[4]arene lower-rim groups, is bound by strong hydrogen bonds to the phenoxy oxygen atoms of the calix[4]arene ligand (structures A, B) and also to one carbonyl oxygen (structure B).     

Das erste oligomere Oxoindat(III): K14[In4O13]

The First Oligooxoindate(III): K₁₄[In₄O₁₃] For the first time K₁₄[In₄O₁₃] was obtained by heating intimate mixtures of K₂O, CdO and elementar In (molar ratio 3.1:1.0:1.0) in closed Ag-cylinders (30 days, 450°C) in form of yellow-brown single crystals. The structure determination by four circle diffractometer data MoKα, 3 689 out of 3 689 I_o(hkl), R = 4.22, R_w = 2.45) confirms the space group P2₁/c with lattice constants a = 687.7 pm; b = 3 118.5 pm; c = 686.4 pm; β = 119.3°; Z = 2. The characteristic feature of the structure is [In₄O₁₃]^14? groups, oligomers consisting of four corner-sharing InO₄ tetrahedra. These groups are connected by crystallographically distinct potassium atoms. The structure is isotypic with Na₁₄[Al₄O₁₃] [2] and K₁₄[Fe₃O₁₃] [3]. ECoN and MAPLE calculationes are discussed.     

DFT-calculated structure of protonated tetraphenyl <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylcalix[4]arene tetraketone

Using DFT calculations, two of the most probable structures (A, B) of the tetraphenyl p-tert-butylcalix[4]arene tetraketone·H₃O⁺ cationic complex species were derived. The hydroxonium ion H₃O⁺, placed in the coordination cavity formed by the calix[4]arene lower-rim groups, is bound by strong hydrogen bonds to the phenoxy oxygen atoms of the calix[4]arene ligand (structures A, B) and also to one carbonyl oxygen (structure B). Correspondence: Emanuel Makrlík, Faculty of Applied Sciences, University of West Bohemia, Pilsen, Czech Republic.     

Homoleptic Metal Carbonyl Cations of the Electron-Rich Metals: Their Generation in Superacid Media Together with Their Spectroscopic and Structural Characterization

Homoleptic carbonyl cations of the electron-rich metals in Groups 8 through 12 are the newest members of the large family of transition metal carbonyls. They can be distinguished from typical metal carbonyl complexes in several respects. Their synthesis entails carbonylation of metal salts in such superacids as fluorosulfuric acid and “magic acid” HSO₃F? SbF₅. Thermally stable salts with [Sb₂F₁₁]^? as counterion are obtained with antimony pentafluoride as reaction medium. Both the [Sb₂F₁₁]^? anion and superacid reaction media have previously found little application in the organometallic chemistry of d-block elements. Also unprecedented in metal carbonyl chemistry are the coordination geometries with coordination numbers 4 (square-planar coordination) and 2 (linear coordination) for the cation. Formal oxidation states of the metals, and the charges of the complex cations, extend from + 1 to +3: thus CO is largely σ-bonded to the metal, and the CO bond is strongly polarized. Minimal metal → CO π-backbonding and a positive partial charge on carbon are manifested in long M? C bonds, short C? O bonds, high frequencies for C? O stretching vibrations (up to 2300 cm^?1), and small ¹³C NMR chemical shifts (up to δ_c, = 121). Prominent examples of these unusual homoleptic carbonyl cations, which were recently the subject of a Highlight in this journal, include the first carbonyl cation of a p-block metal [Hg(CO)₂]²⁺, the first trivalent carbonyl cation [Ir(CO)₆]³⁺, and the first multiply charged carbonyl cation of a 3d metal [Fe(CO)₆]²⁺. In this overview we propose to (a) outline the historical origins of cationic metal carbonyls and their methods of synthesis; (b) present a summary of the general field of carbonyl cations, which has developed over a yery short period of time; (c) discuss the structural and spectroscopic characteritics of metal–CO bonding; (d) discuss the special significance associated with reaction media and the [Sb₂F₁₁]^? anion; and (e) point to the most recent results and anticipated future developments.     

Experimental Evidence for Unusual Protonation of Tetraethyl p-tert-Butylcalix[4]arene Tetraacetate and the Most Probable Structure of the Resulting Complex

Using ¹H and ¹³C NMR, FT IR spectroscopy together with quantum mechanical DFT calculations, we show that tetraethyl p-tert-butylcalix[4]arene tetraacetate (1) forms a stable equimolecular complex with proton in the form of hydroxonium ion in acetonitrile-d ₃. Protons for this complex were offered by hydrogen bis(1,2-dicarbollyl) cobaltate (HDCC) and converted to hydroxonium ions by traces of water. The complex 1·H₃O⁺ adopts a slightly asymmetric conformation, which is distinctly more cone-like than ligand 1. According to spectral evidence, the hydroxonium ion H₃O⁺ is bound mainly to three of the phenoxy oxygen atoms of 1 by strong hydrogen bonds leaving the ester carbonyl groups, which are the usual coordination site for metal cations, free. Theoretical DFT calculations support the bonding to phenoxy oxygen atoms but slightly prefer a structure with one of the carbonyls being involved in the coordination.     

A novel 1:2 cucurbit[8]uril inclusion complex with N-phenylpiperazine hydrochloride

A new 1:2 inclusion complex of cucurbit[8]uril (CB[8]) and protonated N-phenylpiperazine was synthesized and characterized by ¹H NMR and X-ray crystallography. The crystal structure showed that the phenyl rings of the two equivalents of guest encapsulated in the cavity of CB[8] are parallel to one another with a mean plane separation of 3.899 Å. In contrast, the piperazinyl phenyl ammonium moieties slightly protrude from the ureidyl carbonyl lined portals in order to accommodate the ion–dipole interaction between host and guest which provides a substantial driving force for the assembly. The oxygen atoms of the carbonyl groups form hydrogen bonds with the hydrogen atoms in both bridging methylene groups of CB[8] and water molecules. There are also hydrogen bonds formed among CB[8], water, and the protonated piperazinyl rings. These hydrogen bonds are formed between the ureidyl C=O groups and hydrogens in methylenes of piperazinyl rings; through hydrogen bonding N⁺–H···O(H)–H···O=C. The protonated piperazinyl rings connect the carbonyl groups with the bridging water molecules.     

Theoretical study on the protonation of cucurbit[6]uril

Abstract  

The most probable structures of the cucurbit[6]uril·H₃O⁺ and cucurbit[6]uril·(H₃O⁺)₂ cationic complex species have been derived by quantum mechanical DFT calculations. In these two complexes, each of the H₃O⁺ ions is bound by three strong linear hydrogen bonds to three carbonyl oxygen atoms of the parent macrocycle.     

Reactivity of an N,N‐Chelated Germylene Toward Substituted Alkynes,Alkenes, and Allenes

Treatment of N,N‐chelated germylene [(iPr)₂NB(N‐2,6‐Me₂C₆H₃)₂]Ge ( 1 ) with ferrocenyl alkynes containing carbonyl functionalities, FcC≡CC(O)R, resulted in [2+2+2] cyclization and formation of the respective ferrocenylated 3‐Fc‐4‐C(O)R‐1,2‐digermacyclobut‐3‐enes 2 – 4 [R = Me ( 2 ), OEt ( 3 ) and NMe₂ ( 4 )] bearing intact carbonyl substituents. In contrast, the reaction between 1 and PhC(O)C≡CC(O)Ph led to activation of both C≡C and C=O bonds producing bicyclic compound containing two five‐membered 1‐germa‐2‐oxacyclopent‐3‐ene rings sharing one C–C bond, 4,8‐diphenyl‐3,7‐dioxa‐2,6‐digermabicyclo[3.3.0]octa‐4,8‐diene ( 5 ). With N‐methylmaleimide containing an analogous C(O)CH=CHC(O) fragment, germylene 1 reacted under [2+2+2] cyclization involving the C=C double bond, producing 1,2‐digermacyclobutane 6 with unchanged carbonyl moieties. Finally, 1 selectively added to the terminal double bond in allenes CH₂=C=CRR′ giving rise to 3‐(=CRR′)‐1,2‐digermacyclobutanes [R/R′ = Me/Me ( 7 ), H/OMe ( 8 )] bearing an exo‐C=C double bond. All compounds were characterized by ¹H, ¹³C{¹H} NMR, IR and Raman spectroscopy and the molecular structures of 3 , 4 , 5 , and 8 were established by single‐crystal X‐ray diffraction analysis. The redox behavior of ferrocenylated derivatives 2 – 4 was studied by cyclic voltammetry.     

Solid‐state tautomeric structure and invariom refinement of a novel and potent HIV integrase inhibitor

The conformation and tautomeric structure of (Z)‐4‐[5‐(2,6‐difluorobenzyl)‐1‐(2‐fluorobenzyl)‐2‐oxo‐1,2‐dihydropyridin‐3‐yl]‐4‐hydroxy‐2‐oxo‐N‐(2‐oxopyrrolidin‐1‐yl)but‐3‐enamide, C₂₇H₂₂F₃N₃O₅, in the solid state has been resolved by single‐crystal X‐ray crystallography. The electron distribution in the molecule was evaluated by refinements with invarioms, aspherical scattering factors by the method of Dittrich et al. [Acta Cryst. (2005), A 61 , 314–320] that are based on the Hansen–Coppens multipole model [Hansen & Coppens (1978). Acta Cryst. A 34 , 909–921]. The β‐diketo portion of the molecule exists in the enol form. The enol –OH hydrogen forms a strong asymmetric hydrogen bond with the carbonyl O atom on the β‐C atom of the chain. Weak intramolecular hydrogen bonds exist between the weakly acidic α‐CH hydrogen of the keto–enol group and the pyridinone carbonyl O atom, and also between the hydrazine N—H group and the carbonyl group in the β‐position from the hydrazine N—H group. The electrostatic properties of the molecule were derived from the molecular charge density. The molecule is in a lengthened conformation and the rings of the two benzyl groups are nearly orthogonal. Results from a high‐field ¹H and ¹³C NMR correlation spectroscopy study confirm that the same tautomer exists in solution as in the solid state.     

Complexes of lanthanide nitrates with N,N-diethylantipyrine-4-carboxamide

New complexes of lanthanide nitrates with N, N-diethylantipyrine-4-carboxamide (DEAP), with the general formulae [Ln₂(DEAP)₃] [NO₃]₆ (where Ln = La, Pr, Nd, Sm, Tb, Ho, Er, Yb and Y) have been isolated and characterized by chemical analysis and various physical methods such as electrolytic conductance, IR and¹³C NMR spectral data. Electrolytic conductance values and infrared spectral studies indicate that the nitrate groups are coordinated. Infrared and¹³C NMR spectral analysis show that the ligand DEAP is coordinated to the tripositive metal ion through the diethylcarboxamide carbonyl and antipyrine carbonyl oxygens in a bidentate fashion.     

Biosynthesis of the benz[α]anthraquinone antibiotic PD 116198

The labeling pattern obtained from incorporation of a mixture of sodium [1-¹³C]- and [s-¹³C]acetates has confirmed the irregular derivation of the benz[α]anthraquinone skeleton of the angucycline antibiotic PD 116198. Subsequent incorporation of sodium [1-¹³C, ¹⁸O₂]-, and [1-¹³C, 2-²H₃]acetates and of ¹⁸O₂ have revealed the origins of the hydrogen and oxygen atoms of the antibiotic. The possibility of a “two-chain” biosynthesis was tested by feeding ²H-labeled orsellinates; however, no incorporation was detected. PD 116198 seems most plausibly derived by rearrangement of an initially-formed linear tetracyclic intermediate.     

Supramolecular synthesis based on piperidone derivatives and pharmaceutically acceptable co‐formers

The target complexes, bis{(E,E)‐3,5‐bis[4‐(diethylamino)benzylidene]‐4‐oxopiperidinium} butanedioate, 2C₂₇H₃₆N₃O⁺·C₄H₄O₄²⁻, (II), and bis{(E,E)‐3,5‐bis[4‐(diethylamino)benzylidene]‐4‐oxopiperidinium} decanedioate, 2C₂₇H₃₆N₃O⁺·C₁₀H₁₆O₄²⁻, (III), were obtained by solvent‐mediated crystallization of the active pharmaceutical ingredient (API) (E,E)‐3,5‐bis[4‐(diethylamino)benzylidene]‐4‐piperidone and pharmaceutically acceptable dicarboxylic (succinic and sebacic) acids from ethanol solution. They have been characterized by melting point, IR spectroscopy and single‐crystal X‐ray diffraction. For the sake of comparison, the structure of the starting API, (E,E)‐3,5‐bis[4‐(diethylamino)benzylidene]‐4‐piperidone methanol monosolvate, C₂₇H₃₅N₃O·CH₄O, (I), has also been studied. Compounds (II) and (III) represent salts containing H‐shaped centrosymmetric hydrogen‐bonded synthons, which are built from two parallel piperidinium cations and a bridging dicarboxylate dianion. In both (II) and (III), the dicarboxylate dianion resides on an inversion centre. The two cations and dianion within the H‐shaped synthon are linked by two strong intermolecular N⁺—H...⁻OOC hydrogen bonds. The crystal structure of (II) includes two crystallographically independent formula units, A and B. The cation geometries of units A and B are different. The main N—C₆H₄—C=C—C(=O)—C=C—C₆H₄—N backbone of cation A has a C‐shaped conformation, while that of cation B adopts an S‐shaped conformation. The same main backbone of the cation in (III) is practically planar. In the crystal structures of both (II) and (III), intermolecular N⁺—H...O=C hydrogen bonds between different H‐shaped synthons further consolidate the crystal packing, forming columns in the [100] and [10] directions, respectively. Salts (II) and (III) possess increased aqueous solubility compared with the original API and thus enhance the bioavailability of the API.     

Contribution to the Protonation of a Calix[4]arene: DFT Calculated Structure of Protonated p-tert -Butylcalix[4]arenetetrakis( N , N -diethylacetamide)

By using DFT calculations, the most probable structure of the p-tert-butylcalix[4]arenetetrakis(N,N-diethylacetamide) · H₃O⁺ complex species was derived. In this complex, the hydroxonium ion H₃O⁺ is predominantly bound by strong hydrogen bonds to three phenoxy oxygens of the ligand and partly to the remaining phenoxy oxygen atom by two somewhat weaker hydrogen bonds. Besides, the H₃O⁺ cation is also bound to two carbonyl oxygens of the mentioned ligand by further two weaker hydrogen bonds.     

The addition of carbonyl compounds to tetramesitylgermasilene and dimesitylgermylene

Hexamesitylsiladigermirane, 1 , has been photolyzed/thermolyzed in the presence of three representative carbonyl compounds: acetone, pivalaldehyde, and benzaldehyde. In each case, a [2 + 2] adduct between the carbonyl compound and Mes₂Ge = SiMes₂ was formed regioselectively to give a 2,3-silagermaoxetane. The 2,3-silagermaoxetanes have been fully characterized by IR and NMR (¹H, ¹³C, and ²⁹Si) spectroscopy and mass spectrometry. In two cases, the structures have been confirmed by X-ray crystallography: 4,4-dimethyl-2,2,3,3-tetramesityl-2,3-silagermaoxetane, 2a ; crystals are triclinic, space group P1 with Z = 2 in a unit cell of dimensions a = 12.318(3) Å, b = 12.436(2) Å, c = 11.884(2) Å, α = 100.13(1)°, β = 103.80(2)°, and γ = 89.97(2)°. The structure was solved by direct methods and refined by least squares on the basis of 2955 observed reflections to R₁ and wR₂ values of 0.0600 and 0.1363, respectively. The structure of 4-tert-butyl-2,2,3,3-tetramesityl-2,3-silagermaoxetane, 2b , was also determined; crystals are monoclinic, space group Cc with Z = 4 in a unit cell of dimensions a = 11.306(2) Å, b = 21.292(4) Å, c = 16.524(2) Å, and β = 106.83(1)°. The structure was determined by direct methods and refined by full-matrix least squares on the basis of 1817 observed reflections to R₁ and wR₂ values of 0.0621 and 0.1681, respectively. An adduct between dimesitylgermylene and the carbonyl compound was also isolated in each reaction. The structure of the adduct appears to depend upon the steric bulk of the group attached to the carbonyl carbon.     

Contribution to the Protonation of a Calix[4]arene: DFT Calculated Structure of Protonated <Emphasis Type="Italic">p-tert</Emphasis>-Butylcalix[4]arenetetrakis(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethylacetamide)

Summary. By using DFT calculations, the most probable structure of the p-tert-butylcalix[4]arenetetrakis(N,N-diethylacetamide) · H₃O⁺ complex species was derived. In this complex, the hydroxonium ion H₃O⁺ is predominantly bound by strong hydrogen bonds to three phenoxy oxygens of the ligand and partly to the remaining phenoxy oxygen atom by two somewhat weaker hydrogen bonds. Besides, the H₃O⁺ cation is also bound to two carbonyl oxygens of the mentioned ligand by further two weaker hydrogen bonds.     

Theoretical Investigation of Mono and Multiply Oxygenated C70 Fullerenes

We have applied DFT calculations to investigate atomic arrangements of fullerene oxides, C₇₀O _n with n = 1, 5, 15, 20, and 25. The oxidation reaction energies are generally exothermic. In the case of C₇₀O, the most stable configuration is the one in which the oxygen atom is chemisorbed on the C–C bond at the equatorial belt of fullerene with oxidoannulene like structure. In highly oxygenated fullerenes, the addition of oxygen atoms on the [6, 6] bonds near the pole area of the C₇₀ leads to lower values of reaction energies. Among these, C₇₀O₂₀ with three oxygen atoms adsorbed on a benzenoid ring yields the most energetically favorable configuration. Different positions of the oxygen atoms on the surface of the mono oxygenated fullerenes lead to significant differences in their ¹⁷O NQR parameters. Meanwhile, the ¹⁷O NQR parameters of the highly oxygenated fullerenes divide their oxygen nuclei into a few groups. For example, the electric field gradient tensor for oxygen atoms chemisorbed on the [6, 5] bonds with larger η values becomes considerably asymmetric in comparison to those chemisorbed on the [6, 6] bonds. These are also reflected in the calculated natural charges of oxygen atoms.     

Fragmentation of some 4<Emphasis Type="Italic">H</Emphasis>-pyran-4-one and pyridin-4-one derivatives under electron impact

Fragmentation of 13 compounds of the 4H-pyran-4-one and pyridin-4-one series under electron impact involves formation of rearrangement ions stabilized by multiple bonds and oxygen atoms (mostly [RC≡O]⁺ and RCH=OR′]⁺), as well of neutral molecules with low enthalpies of formation (CO, H₂O, CH₂O, CO₂, CH₂=C=O, C₃O₂, and RCOOH; R = H, Me, HC≡C, HOC≡C).     

[As(V)As(III)O6]: An uncommon anion group in the crystal structure of K2Cu3(As2O6)2

The crystal structure of K₂Cu₃(As₂O₆)₂ was determined from single-crystal X-ray data by a direct method strategy and Fourier summations [a = 10.359(4) Å, B = 5.388(2)Å, C = 11.234(4) Å, β = 110.48(2)°; space group C2/m; Z = 2; R_w = 0.025 for 1199 reflections up to sin /λ = 0.81 Å⁻¹]. In detail, the structure consists of As(V)O₄ tetrahedra and As(III)O₃ pyramids linked by a common O corner atom to [As(V)As(III)O₆]⁴⁻ groups with symmetry m. The bridging bonds As(V)---O [1.749(3) Å] and As(III)---O [1.838(2) Å] are definitely longer than the other As(V)---O bonds [mean 1.669 Å] and As(III)---O bonds [1.764(2) Å, 2×]. The angle As(V)---O---As(III) is 123.0(1)°. The Cu atoms are [4 + 2]- and [4 + 1]-, and the K atom is [9]-coordinated to oxygen atoms. The As₂O₆ groups and the Cu coordination polyhedra are linked to sheets parallel to (001). These sheets are connected by the K atoms. Single crystals of K₂Cu₃(As₂O₆)₂ suitable for X-ray work were synthesized under hydrothermal conditions.     

Theoretical study on the protonation of bambus[6]uril

Abstract  

Quantum mechanical density functional theory (DFT) calculations were used to derive the most probable structures of the bambus[6]uril·H₃O⁺ and bambus[6]uril·(H₃O⁺)₂ cationic complex species. In these two complexes, each of the considered H₃O⁺ ions is bound by three strong linear hydrogen bonds to the three corresponding carbonyl oxygens of the parent macrocyclic receptor.     

Benzindoles XII. Spectra and three-dimensional structures of [6,7]- and [4,5]benzoskatolideneacetones

It was found by means of their ER, UV, and PMR spectra that [6,7]benzoskatolideneacetones have a side chain in the trans-s-cis form, whereas the [4, 5] isomers have a side chain in the cis-s-cis form. It was concluded from the integral intensities of the bands of the vibrations of the double bond (A_C=C)) and the parameters of the UV spectra that the investigated molecules have a planar structure. The A_C=C) integral intensities in the IR spectra exceed the previously observed values and, in the case of [6,7]benzoskatolideneacetones, reach ～6· 10⁴ mole^?1liter·cm^?2.