Carbon Dioxide Fixation with Dialkyltellurium(IV) Dihydroxides

Aqueous solutions of Me₂Te(OH)₂ and (CH₂)₄Te(OH)₂ readily absorb carbon dioxide giving rise to the formation of the dialkyltelluroxane carbonates (Me₂TeOTeMe₂CO₃)_n ( 1 ) and HO(CH₂)₄TeOTe(CH₂)₄CO₃Te(CH₂)₄OH·2H₂O ( 2 ·2H₂O), which were characterised by ¹³C MAS and ¹²⁵Te MAS NMR spectroscopy as well as X‐ray crystallography. The spatial arrangement of the tellurium atoms is defined by C₂O₂ donor sets in the primary coordination sphere and one or two secondary Te···O contacts, which involve coordination of the carbonate moieties. In turn, the different Te–O coordination modes render a lack of symmetry to the carbonate moieties, which show significantly different C–O bond lengths, an important feature when contemplating the C–O bond activation in carbonates. The structural and spectroscopic parameters of 1 and 2 are discussed in comparison with other heavy p‐block element carbonates. In solution, electrolytic dissociation of 1 and 2 takes place.     

Dimerization of New T‐shaped Hypervalent Organotellurium(II) Dihalides: Synthesis and Structural Characterization of (PyH)[mesTeIX] (Py = pyridine; mes = mesityl; X = Cl,Br, I)

[mesTe]₂ reacts with iodine in toluene and further with (C₅H₆N)⁺X^? (X = I, Br, Cl) to give (PyH)[mesTeI₂] ( 1 ), (PyH)[mesTeIBr] ( 2 ) and (PyH)[mesTeICl] ( 3 ). The anionic fragments [(mes)TeI₂] and [(mes)TeIBr] of 1 and 2 are assembled as dimers by reciprocal, secondary Te···X interactions, linked also to the pyridinium cations through μ‐NH···X bonding. The anion [(mes)TeICl]^? ( 3 ) do not interact with neighboring anionic moieties, achieving also secondary NH···Cl bonding toward the pyridinium cation. The dimerization ability – with attaining of additional interionic hydrogen bridges – of 1 and 2 allow them to be viewed as partially “molecular” and as hypervalent compounds of Te^II, for which the observed linearity of the I–Te–X system and the similarity of the Te–X bond distances are expected.     

Supramolecular Assembling through Anionic Iodine Secondary Bonds: Synthesis and X‐ray Characterization of (Et4N)[PhTeI4] and (Et4N)[(β‐Naphthyl)TeI4]

[PhTe]₂ and [(β‐naphthyl)Te]₂ react with iodine and tetraethylammonium iodide in toluene/methanol to give (Et₄N)[PhTeI₄] and (Et₄N)[(β‐Naphthyl)TeI₄]. The complexes were analysed by single crystal X‐ray diffraction affording the centrosymmetric monoclinic space group P2₁/c. In the novel compounds only anionic interactions of the types Te···I and I···I take place, cation‐anion effective contacts do not occur. Both anions [PhTeI₄] and [(β‐naphthyl)TeI₄] exhibit square pyramidal coordination at tellurium, with the iodine atoms in the basal positions and the organic groups apical. The tellurium centers achieve an octahedral coordination in the whole lattices through Te···I secondary bonds with the adjacent ionic species. Only the Te–I‐ and I–I‐secondary bonds behave as structure‐forming interactions in the self‐organization of the supramolecular anionic gatherings. New evidences show that for organyltellurates (Q)[PhTeX₄] (Q = protonated amines, amides or amino acids; X = Cl, Br, I), NH···X hydrogen bondings are able to hinder the anionic halogen‐halogen secondary interactions. In case of the more frequent I···I interactions, they have been observed only in the absence of NH···I hydrogen bonds.     

The first X-ray crystal structure of a mercury(II) complex with an SP(N)3-based ligand: Synthesis and crystal structure of SP(NC5H10)3 and [Hg{SP(NC5H10)3}Cl2]2

The synthesis, spectral characteristics (IR and NMR), elemental analysis and X-ray crystal structure of phosphorothioic triamide SP(NC₅H₁₀)₃ (1) and its dinuclear mercury(II) complex [Hg₂(μ-Cl)₂(Cl)₂{SP(NC₅H₁₀)₃}₂] (2) were investigated. A survey using the Cambridge Structural Database (CSD, version 5.38, May 2017) shows structures of coordination compounds of Au, Ag, Cd, Cu, Li, Mo, Ni, Pd, Te, Ti, Zn, and Zr with sulfur-donor SP(N)₃-based ligands; the complex 2 is the first example of a mercury complex with the SP(N)₃-based ligand studied by X-ray crystallography. Valence bond calculation was performed for the Hg–S bond in 2 and compared with the Hg–O bond in the only structure with a Cl₂Hg–OP(N)₃ structural motive in the CSD. The calculation confirms a more covalent nature of the Hg–S bond with respect to the Hg–O bond made by the EP(N)₃-based ligands (E?=?S, O). The supramolecular structures based on C–H···S?=?P contacts in 1 and C–H···S═P and C–H···Cl–Hg assemblies in 2 are discussed.     

Synthesis and Crystal Structure of Tellurium(II) bis(2‐methoxycarbonylethanethiolate): A Novel Coordination Mode of Tellurium

The tellurium(II) dithiolates Te[SCH₂CH₂C(O)OCH₃]₂, ( 1 ), Te[SCH₂CH₂CH₂SC(O)CH₃]₂, ( 2 ), and Te[SCH₂CH₂CH₂CH₂SC(O)CH₃]₂, ( 3 ) were synthesized from Te(S^tBu)₂ and the corresponding thiol. All compounds are sensitive toward higher temperatures and light and decompose to elemental tellurium and the disulfide. In the solid state, the Te atom of 1 exhibits the novel Te(S₂Te₂) coordination mode. Additionally to the two Te—S bonds, each Te atom forms two long Te···Te contacts to neighboring molecules, leading to a coordination number of four and a distorted sawhorse configuration. No intramolecular Te···O interactions are present in the solid state, in accordance with ab initio calculations (MP2/ecp‐basis) for the isolated molecule. ¹²⁵Te NMR shifts of all compounds lay within a narrow range and close to the respective shift of other Te(SCH₂R)₂ compounds. VT ¹²⁵Te NMR spectra gave no hint to donor acceptor interactions in solution for any of the compounds and thus corroborate results from IR‐spectroscopy, ab initio geometry optimizations, and thermochemical calculations.     

Synthesis and Crystal Structure of Manganese‐tris(1,2‐ethanediamine)tetratelluride [Mn(en)3]Te4 Exhibiting Intermolecular Interactions between the Tetratelluride Anions

Air‐sensitive black crystals of the new compound [Mn(en)₃]Te₄ were synthesized by reacting MnCl₂ · 4 H₂O, K₂Te₃ and elemental Te in 1,2‐ethanediamine (en) under solvothermal conditions at 433 K. The compound crystallizes in the monoclinic space group P2₁/n with lattice parameters a = 839.51(7) pm, b = 1551.3(1) pm, c = 1432.6(1) pm, and β = 90.28(2)°. Isolated [Mn(en)₃]²⁺ cations and Te₄^2– anions are arranged in an alternating fashion parallel to the crystallographic b‐axis. One terminal Te atom of the Te₄^2– anions exhibits a short intermolecular contact to a neighboured anion thus forming Te₈^4– anions. A slightly longer interionic Te…Te separation is observed between two of the inner Te atoms of neighboured Te₈^4– anions. Taking these longer separations into account infinite Te‐chains are formed running parallel to [001]. The intermolecular Te…Te interactions affect the Te–Te bond lengths within the Te₄^2– anion leading to a lengthening of the average Te–Te distance. Short N–H…Te distances indicate hydrogen bonding between the cations and anions. DTA‐TG measurements show that at 441 K the material decomposes in one step. The resulting crystalline material consists of MnTe₂ and Te.     

The first crystal structures of six‐ and seven‐membered tellurium‐ and nitrogen‐containing (Te—N) heterocycles: 2H‐1,4‐benzotellurazin‐3(4H)‐one and 2,3‐dihydro‐1,5‐benzotellurazepin‐4(5H)‐one

There is a paucity of data concerning the structures of six‐ and seven‐membered tellurium‐ and nitrogen‐containing (Te—N) heterocycles. The title compounds, C₈H₇NOTe, (I), and C₉H₉NOTe, (II), represent the first structurally characterized members of their respective classes. Both crystallize with two independent molecules in the asymmetric unit. When compared to their sulfur analogs, they exhibit slightly greater deviations from planarity to accommodate the larger chalcogenide atom, with (II) adopting a pronounced twist‐boat conformation. The C—Te—C angles of 85.49 (15) and 85.89 (15)° for the two independent molecules of (I) were found to be somewhat smaller than those of 97.4 (2) and 97.77 (19)° for the two independent molecules of (II). The C—Te bond lengths [2.109 (4)–2.158 (5) Å] are in good agreement with those predicted by the covalent radii. Intermolecular N—H...O hydrogen bonding in (I) forms centrosymmetric R₂²(8) dimers, while that in (II) forms chains. In addition, intermolecular Te...O contacts [3.159 (3)–3.200 (3) Å] exist in (I).     

Functionalized Organotellurium Halides: Synthesis,Characterization, and Observation of Intra- and Intermolecular Secondary Bonding

Abstract

Activated tellurium, but not selenium, reacts with para-substituted benzoylmethyl bromides as well as with iodoacetamide at their melting points in absence of a solvent to give bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC₆H₄COCH₂)₂TeBr₂, (Y = H, Me, and MeO) and bis(acetamido)tellurium diiodide, (H₂NCOCH₂)₂TeI₂, respectively. Quick reduction of (p-YC₆H₄COCH₂)₂TeBr₂, with sodium metabisulphite in a two-phase system yields crystalline (p-YC₆H₄COCH₂)₂Te. These tellurides undergo smooth oxidative addition of halogens, interhalogen ICl or a pseudohalogen (SCN)₂. Intramolecular coordination of the carbonyl group in these functionalized diorganotellurium dihalides is evident from IR spectra and shorter Te···O (carbonyl) distances in comparison to the sum of van der Waals radii and completes six coordination around Te atom. Not unexpectedly, therefore, intermolecular secondary bonding effects of the type Te…O, Te···X and X···X are missing in (PhCOCH₂)₂TeBr₂, (p-MeOC₆H₄COCH₂)TeBr₂ and (PhCOCH₂)₂TeI₂. Instead, these compounds provide rare examples, among organotellurium compounds, of supramolecular architecture, where C–H···Br and C–H···O hydrogen bonds and π-π (phenyl ring) interactions appear to be the noncovalent intermolecular associative forces that dominate the crystal packing.     

Twinning by merohedry in bis(4‐methoxyphenyl)tellurium(IV) diiodide dimethyl sulfoxide hemisolvate

Green crystals of the title compound, C₁₄H₁₄I₂O₂Te·0.5C₂H₆OS, space group P3₂, show twinning by merohedry (class II). The asymmetric unit contains two organotellurium molecules and one dimethyl sulfoxide (DMSO) molecule. The crystal structure displays secondary Te...I and Te...O(DMSO) bonds that lead to [(4‐MeOC₆H₄)₂TeI₂]₂·DMSO supramolecular units in which the two independent organotellurium molecules are bridged by the DMSO O atom. In addition to these secondary bonds, I...I interactions link translationally equivalent organotellurium molecules to form nearly linear ...I—Te—I...I—Te—I... chains. These chains are crosslinked, forming two‐dimensional arrays parallel to (001). The crystal packing consists of a stacking of these sheets, which are related by the 3₂ axis. This study describes an unusual dimeric arrangement of X—Te—X groups.     

A novel single‐electron sodium bond system of H3C···Na?Y (YH,OH, F,CCH, CN,and NC)

A novel single‐electron sodium bond system of H₃C···Na? H (I), H₃C···Na? OH(II), H₃C···Na? F(III), H₃C···Na‐CCH(IV), H₃C···Na? CN (V) and H₃C···Na? NC (VI) complexes has been studied by using MP2/6‐311++G** and MP2/aug‐cc‐pVTZ methods for the first time. We demonstrated that the single‐electron sodium bond H₃C···Na? Y formed between H₃C and Na? Y (Y?H, OH, F, CCH, CN, and NC) could induce the Na? Y increased and stretching frequencies of I–IV and VI are red‐shifted, including the Na? N bond in complex V is blue‐shifted abnormally. The interaction energies are calculated at two levels of theory [MP2, CCSD(T)] with different basis. The results shows that the strength of binding bond in group 2 (IV–VI) with π electrons are stronger than that of group 1 (I–III) without π electrons. For all complexes, the main orbital interactions between moieties H₃C and Na? Y are LP₁(C)→LP*₁(Na). By comparisons with some related systems, it is concluded that the strength of single‐electron bond is increased in the order: hydrogen bond < bromine bond < sodium bond < lithium bond. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Five pseudopolymorphs and a cocrystal of nitrofurantoin

The antibiotic nitrofurantoin {systematic name: (E)‐1‐[(5‐nitro‐2‐furyl)methylideneamino]imidazolidine‐2,4‐dione} is not only used for the treatment of urinary tract infections, but also illegally applied as an animal food additive. Since derivatives of 2,6‐diaminopyridine might serve as artificial receptors for its recognition, we crystallized one potential drug–receptor complex, nitrofurantoin–2,6‐diacetamidopyridine (1/1), C₈H₆N₄O₅·C₉H₁₁N₃O₂, (I·II). It is characterized by one N—H...N and two N—H...O hydrogen bonds and confirms a previous NMR study. During the crystallization screening, several new pseudopolymorphs of both components were obtained, namely a nitrofurantoin dimethyl sulfoxide monosolvate, C₈H₆N₄O₅·C₂H₆OS, (Ia), a nitrofurantoin dimethyl sulfoxide hemisolvate, C₈H₆N₄O₅·0.5C₂H₆OS, (Ib), two nitrofurantoin dimethylacetamide monosolvates, C₈H₆N₄O₅·C₄H₉NO, (Ic) and (Id), and a nitrofurantoin dimethylacetamide disolvate, C₈H₆N₄O₅·2C₄H₉NO, (Ie), as well as a 2,6‐diacetamidopyridine dimethylformamide monosolvate, C₉H₁₁N₃O₂·C₃H₇NO, (IIa). Of these, (Ia), (Ic) and (Id) were formed during cocrystallization attempts with 1‐(4‐fluorophenyl)biguanide hydrochloride. Obviously nitrofurantoin prefers the higher‐energy conformation in the crystal structures, which all exhibit N—H...O and C—H...O hydrogen‐bond interactions. The latter are especially important for the crystal packing. 2,6‐Diacetamidopyridine shows some conformational flexibility depending on the hydrogen‐bond pattern.     

Supramolecular hydrogen‐bonding patterns in salts of the antifolate drugs trimethoprim and pyrimethamine

Nine salts of the antifolate drugs trimethoprim and pyrimethamine, namely, trimethoprimium [or 2,4‐diamino‐5‐(3,4,5‐trimethoxybenzyl)pyrimidin‐1‐ium] 2,5‐dichlorothiophene‐3‐carboxylate monohydrate (TMPDCTPC, 1:1), C₁₄H₁₉N₄O₃⁺·C₅HCl₂O₂S⁻, ( I ), trimethoprimium 3‐bromothiophene‐2‐carboxylate monohydrate, (TMPBTPC, 1:1:1), C₁₄H₁₉N₄O₃⁺·C₅H₂BrO₂S⁻·H₂O, ( II ), trimethoprimium 3‐chlorothiophene‐2‐carboxylate monohydrate (TMPCTPC, 1:1:1), C₁₄H₁₉N₄O₃⁺·C₅H₂ClO₂S⁻·H₂O, ( III ), trimethoprimium 5‐methylthiophene‐2‐carboxylate monohydrate (TMPMTPC, 1:1:1), C₁₄H₁₉N₄O₃⁺·C₆H₅O₂S⁻·H₂O, ( IV ), trimethoprimium anthracene‐9‐carboxylate sesquihydrate (TMPAC, 2:2:3), C₁₄H₁₉N₄O₃⁺·C₁₅H₉O₂⁻·1.5H₂O, ( V ), pyrimethaminium [or 2,4‐diamino‐5‐(4‐chlorophenyl)‐6‐ethylpyrimidin‐1‐ium] 2,5‐dichlorothiophene‐3‐carboxylate (PMNDCTPC, 1:1), C₁₂H₁₄ClN₄⁺·C₅HCl₂O₂S⁻, ( VI ), pyrimethaminium 5‐bromothiophene‐2‐carboxylate (PMNBTPC, 1:1), C₁₂H₁₄ClN₄⁺·C₅H₂BrO₂S⁻, ( VII ), pyrimethaminium anthracene‐9‐carboxylate ethanol monosolvate monohydrate (PMNAC, 1:1:1:1), C₁₂H₁₄ClN₄⁺·C₁₅H₉O₂⁻·C₂H₅OH·H₂O, ( VIII ), and bis(pyrimethaminium) naphthalene‐1,5‐disulfonate (PMNNSA, 2:1), 2C₁₂H₁₄ClN₄⁺·C₁₀H₆O₆S₂²⁻, ( IX ), have been prepared and characterized by single‐crystal X‐ray diffraction. In all the crystal structures, the pyrimidine N1 atom is protonated. In salts ( I )–( III ) and ( VI )–( IX ), the 2‐aminopyrimidinium cation interacts with the corresponding anion via a pair of N—H…O hydrogen bonds, generating the robust R₂²(8) supramolecular heterosynthon. In salt ( IV ), instead of forming the R₂²(8) heterosynthon, the carboxylate group bridges two pyrimidinium cations via N—H…O hydrogen bonds. In salt ( V ), one of the carboxylate O atoms bridges the N1—H group and a 2‐amino H atom of the pyrimidinium cation to form a smaller R₂¹(6) ring instead of the R₂²(8) ring. In salt ( IX ), the sulfonate O atoms mimic the role of carboxylate O atoms in forming an R₂²(8) ring motif. In salts ( II )–( IX ), the pyrimidinium cation forms base pairs via a pair of N—H…N hydrogen bonds, generating a ring motif [R₂²(8) homosynthon]. Compounds ( II ) and ( III ) are isomorphous. The quadruple DDAA (D = hydrogen‐bond donor and A = hydrogen‐bond acceptor) array is observed in ( I ). In salts ( II )–( IV ) and ( VI )–( IX ), quadruple DADA arrays are present. In salts ( VI ) and ( VII ), both DADA and DDAA arrays co‐exist. The crystal structures are further stabilized by π–π stacking interactions [in ( I ), ( V ) and ( VII )–( IX )], C—H…π interactions [in ( IV )–( V ) and ( VII )–( IX )], C—Br…π interactions [in ( II )] and C—Cl…π interactions [in ( I ), ( III ) and ( VI )]. Cl…O and Cl…Cl halogen‐bond interactions are present in ( I ) and ( VI ), with distances and angles of 3.0020 (18) and 3.5159 (16) Å, and 165.56 (10) and 154.81 (11)°, respectively.     

Eight new crystal structures of 5‐(hydroxymethyl)uracil, 5‐carboxyuracil and 5‐carboxy‐2‐thiouracil: insights into the hydrogen‐bonded networks and the predominant conformations of the C5‐bound residues

In order to examine the preferred hydrogen‐bonding pattern of various uracil derivatives, namely 5‐(hydroxymethyl)uracil, 5‐carboxyuracil and 5‐carboxy‐2‐thiouracil, and for a conformational study, crystallization experiments yielded eight different structures: 5‐(hydroxymethyl)uracil, C₅H₆N₂O₃, (I), 5‐carboxyuracil–N,N‐dimethylformamide (1/1), C₅H₄N₂O₄·C₃H₇NO, (II), 5‐carboxyuracil–dimethyl sulfoxide (1/1), C₅H₄N₂O₄·C₂H₆OS, (III), 5‐carboxyuracil–N,N‐dimethylacetamide (1/1), C₅H₄N₂O₄·C₄H₉NO, (IV), 5‐carboxy‐2‐thiouracil–N,N‐dimethylformamide (1/1), C₅H₄N₂O₃S·C₃H₇NO, (V), 5‐carboxy‐2‐thiouracil–dimethyl sulfoxide (1/1), C₅H₄N₂O₃S·C₂H₆OS, (VI), 5‐carboxy‐2‐thiouracil–1,4‐dioxane (2/3), 2C₅H₄N₂O₃S·3C₆H₁₂O₃, (VII), and 5‐carboxy‐2‐thiouracil, C₁₀H₈N₄O₆S₂, (VIII). While the six solvated structures, i.e. (II)–(VII), contain intramolecular S(6) O—H…O hydrogen‐bond motifs between the carboxy and carbonyl groups, the usually favoured R₂²(8) pattern between two carboxy groups is formed in the solvent‐free structure, i.e. (VIII). Further R₂²(8) hydrogen‐bond motifs involving either two N—H…O or two N—H…S hydrogen bonds were observed in three crystal structures, namely (I), (IV) and (VIII). In all eight structures, the residue at the ring 5‐position shows a coplanar arrangement with respect to the pyrimidine ring which is in agreement with a search of the Cambridge Structural Database for six‐membered cyclic compounds containing a carboxy group. The search confirmed that coplanarity between the carboxy group and the cyclic residue is strongly favoured.     

Cocrystals of 1,4‐diethynylbenzene with 1,3‐diacetylbenzene and benzene‐1,4‐dicarbaldehyde exhibiting strong nonconventional alkyne–carbonyl C—H…O hydrogen bonds between the components

Weak interactions between organic molecules are important in solid‐state structures where the sum of the weaker interactions support the overall three‐dimensional crystal structure. The sp‐C—H…N hydrogen‐bonding interaction is strong enough to promote the deliberate cocrystallization of a series of diynes with a series of dipyridines. It is also possible that a similar series of cocrystals could be formed between molecules containing a terminal alkyne and molecules which contain carbonyl O atoms as the potential hydrogen‐bond acceptor. I now report the crystal structure of two cocrystals that support this hypothesis. The 1:1 cocrystal of 1,4‐diethynylbenzene with 1,3‐diacetylbenzene, C₁₀H₆·C₁₀H₁₀O₂, (1), and the 1:1 cocrystal of 1,4‐diethynylbenzene with benzene‐1,4‐dicarbaldehyde, C₁₀H₆·C₈H₆O₂, (2), are presented. In both cocrystals, a strong nonconventional ethynyl–carbonyl sp‐C—H…O hydrogen bond is observed between the components. In cocrystal (1), the C—H…O hydrogen‐bond angle is 171.8 (16)° and the H…O and C…O hydrogen‐bond distances are 2.200 (19) and 3.139 (2) Å, respectively. In cocrystal (2), the C—H…O hydrogen‐bond angle is 172.5 (16)° and the H…O and C…O hydrogen‐bond distances are 2.25 (2) and 3.203 (2) Å, respectively.     

Two‐dimensional hydrogen‐bond network in bis­[(ferrocenylmethyl)­dimethyl­ammonium] sulfate penta­hydrate

In the title compound, [Fe(C₅H₅)(C₈H₁₃N)]₂(SO₄)·5H₂O, the Fe—C bond lengths lie in the range 2.021 (3)–2.047 (2) Å. Inter­molecular N—H⋯O and O—H⋯O hydrogen bonds link the cations, sulfate anions and water mol­ecules into a two‐dimensional hydrogen‐bonded network, which stabilizes the crystal packing.     

Synthesis,Spectroscopy, X‐ray Crystallography,and DFT Computations of Nanosized Phosphazenes

Nanoparticles of nine phosphazenes with general formula 4‐CH₃C₆H₄S(O)₂N=PX₃ [X = Cl ( A ), NC₄H₈ ( 1 ), NC₆H₁₂ ( 2 ), NC₄H₈N–C(O)OC₂H₅ ( 3 ), NC₄H₈N–C(O)OC₆H₅ ( 4 ), NC₄H₈O ( 5 ), NHCH₂–C₄H₇O ( 6 ), N(CH₃)(C₆H₁₁) ( 7 ), NHCH₂–C₆H₅ ( 8 ), and 2‐NH‐NC₅H₄ ( 9 )] were synthesized using ultrasonic method and characterized by ¹H, ¹³C, ³¹P NMR, FT‐IR, fluorescence, as well as UV/Vis spectroscopy and additionally with XRD, FE‐SEM, N₂ sorption, and elemental analysis. The ³¹P NMR spectra of compounds 1 – 9 reveal the most up field shift δ(³¹P) for 9 at –11.45 ppm reflecting the most electron donation of 2‐aminopyridinyl rings through resonance to the phosphorus atom. The ¹H, ¹³C NMR spectra of 7 exhibit two sets of signals for the hydrogen and carbon atoms of its two isomers present in the solution state in 1:4 ratio. The FE‐SEM micrographs illustrate that the nanoparticles of compounds 1 – 9 have spherical morphology and a size of 27–42 nm. From the XRD patterns, the crystal sizes were estimated to about 24–86 nm. The highest bandgap was measured for 3 (3.81 eV) whereas the smallest was measured for 8 (3.50 eV). The structures of two polymorphs of compound 5 ( 5 , 5′ ) were determined by X‐ray crystallography at 120 K. Both of these polymorphs are triclinic with P1 space group but 5 has a doubled unit cell volume and two symmetrically independent molecules ( 5a and 5b ). In structures 5a and 5′ , the phosphorus and all endocyclic atoms of two morpholinyl rings display disorder, whereas the molecule 5b does not show disorder. The strong intermolecular O–H ··· O hydrogen bonds plus weak intermolecular C–H ··· O and C–H ··· N interactions create three‐dimensional polymers in the crystalline networks of 5 and 5′ . The DFT computations illustrate that molecule 5b is more stable than 5a by –1.1062 and –0.9779 kcal · mol^–1 at B3LYP and B3PW91 levels, respectively. The NBO calculations presented sp³d hybridization for phosphorus and sulfur atoms and sp², sp³ hybrids for the nitrogen and oxygen atoms.     

Cocrystals of 6‐propyl‐2‐thiouracil: N—H...O versus N—H...S hydrogen bonds

In order to investigate the relative stability of N—H...O and N—H...S hydrogen bonds, we cocrystallized the antithyroid drug 6‐propyl‐2‐thiouracil with two complementary heterocycles. In the cocrystal pyrimidin‐2‐amine–6‐propyl‐2‐thiouracil (1/2), C₄H₅N₃·2C₇H₁₀N₂OS, (I), the `base pair' is connected by one N—H...S and one N—H...N hydrogen bond. Homodimers of 6‐propyl‐2‐thiouracil linked by two N—H...S hydrogen bonds are observed in the cocrystal N‐(6‐acetamidopyridin‐2‐yl)acetamide–6‐propyl‐2‐thiouracil (1/2), C₉H₁₁N₃O₂·2C₇H₁₀N₂OS, (II). The crystal structure of 6‐propyl‐2‐thiouracil itself, C₇H₁₀N₂OS, (III), is stabilized by pairwise N—H...O and N—H...S hydrogen bonds. In all three structures, N—H...S hydrogen bonds occur only within R₂²(8) patterns, whereas N—H...O hydrogen bonds tend to connect the homo‐ and heterodimers into extended networks. In agreement with related structures, the hydrogen‐bonding capability of C=O and C=S groups seems to be comparable.     

Orthotelluric Acid as Substitute for Crystal‐Water: Syntheses and Crystal Structure of the Co‐crystallate [Te(OH)6 · 2 Adenine · 4 H2O] and the Disodium Ditellurate(VI) Aggregate {[Te2O2(OH)6(ONa)2]2[NaOH · 12.5 H2O]}

Supramolecular aspects on Te(OH)₆ as substitute for crystal‐water in adenine hydrate complexes and the first disodium ditellurate(VI) are reported. The co‐crystallate [Te(OH)₆ · 2 adenine · 4 H₂O] ( 1 ) has been prepared in 41% yield from the 1 : 1 mixing of Te(OH)₆ with the nitrogenous base adenine. The adduct of infinite stacks of adenine molecules, Te(OH)₆ and water not only proves that Te(OH)₆ mimicks the role of water in the related hydrate adenine · 3 H₂O but also shows that the inclusion of Te(OH)₆ raises the number of HO–H and N–HO contacts and therefore increases the distance between the adenine rings to 3.31 Å in 1 in comparison to that in adenine trihydrate (3.22 Å). Additionally, the disodium ditellurate(VI) aggregate {[Te₂(O)₂(OH)₆(ONa)₂]₂ [NaOH · 12.5 H₂O]} ( 2 ) resulted from the reaction of 1 with 2 molar equivalents of aqueous NaOH. Dinuclear 2 represents the first X‐ray diffraction characterized example of a sodium tellurate(VI) constructed from [Te₂O₄(OH)₆]^2– dianions.     

New Mixed Ligand Organotellurium(IV) Compounds Containing Dithiocarbamates and the More Flexible Imidotetraphenyldithiodiphosphinates. The Crystal Structures of C8H8Te(S2CNEt2)[(SPPh2)2N] · H2O,C8H8Te(S2CNC5H10)[(SPPh2)2N], and C8H8Te(S2CNC4H8S)[(SPPh2)2N]

The synthesis of the following mixed ligand organotellurium(IV) compounds C₈H₈Te(S₂CNEt₂)[(SPPh₂)₂N] · H₂O ( 1 ), C₈H₈Te(S₂CNC₅H₁₀)[(SPPh₂)₂N] ( 2 ), C₈H₈Te(S₂CNC₄H₈O)[(SPPh₂)₂N] ( 3 ) and C₈H₈Te(S₂CNC₄H₈S)[(SPPh₂)₂N] ( 4 ) was achieved. They were characterized by IR, ¹H, ¹³C, ³¹P and ¹²⁵Te NMR, mass spectroscopy, and elemental analyses. The X‐ray crystal structures of 1 , 2 and 4 were determined. The both types of ligands display an asymmetrical chelating coordination mode on interaction with the tellurium atom. When these aniso‐bonded donor atoms are included in the coordination sphere, the tellurium atom exhibit an effective co‐ordination number of seven. The arrangement may be described as 1 : 2 : 2 : 2 coordination with a presumably stereoactive lone‐pair of electrons.     

Hydroboration of the Amino(imino)borane [Me3C(Me3Si)N]B[N(CMe3)]

The formation of four products of the type Me₃C(Me₃Si)N=BH–N(CMe₃)=BR'₂ [BR'₂ = B(CHMeiPr)₂ ( 1 ), B(c‐C₆H₁₁)₂ ( 2 ), B(C₈H₁₄) ( 3 ), B(O₂C₆H₄) ( 4 )] from the iminoborane Me₃C(Me₃Si)N–···B=···N(CMe₃) and the hydroboranes (R'₂BH)₂ is described. Crystal structure analysis reveals the molecule 1 to have an N=B–N=B backbone with two orthogonal N=B bond planes and, hence, no conjugation between the two B–N double bonds.