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Studies of the supramolecular chemistry of iso‐tellurazole N‐oxides have been confined to non‐polar media until now. To overcome that limitation, an iso‐tellurazole N‐oxide was derivatized with a primary alcohol group; the compound is soluble in polar solvents and stable in acidic to neutral aqueous media. Nickel (II) and iron (II) form macrocyclic complexes with six molecules of that iso‐tellurazole N‐oxide in a hitherto not‐observed macrocyclic arrangement defined by CTe⋅⋅⋅O chalcogen bonds and κ6‐O bound to the metal ion. This behaviour is in sharp contrast with the κn‐Te (n=1,2,4) complexes formed by soft metal ions. [ABSTRACT FROM AUTHOR]

Reactions of the ethylene hydride complex trans-[(dmpe)2MnH(C2H4)] (1) with secondary hydrogermanes H2GeR2 at 55–60 °C afforded the base-free terminal germylene hydride complexes trans-[(dmpe)2MnH(＝GeR2)] (R = Ph; 2a, R = Et; 2b). Room temperature reactions of 2a or 2b with an excess of the primary hydrogermanes H3GeR′ (R′ = Ph or nBu) afforded trans-[(dmpe)2MnH(＝GeHR′)] (R′ = Ph; 3a, R′ = nBu; 3b) in rapid equilibrium with small amounts of 2a/b, as well as the digermyl hydride complex mer-[(dmpe)2MnH(GeH2R′)2] {R′ = Ph (4a) or nBu (4b)} and the trans-hydrogermane germyl complex trans-[(dmpe)2Mn(GeH2R′)(HGeH2R′)] {R′ = Ph (5a) or nBu (5b)}. Pure 3b was isolated from the reaction of 2b with H3GenBu, whereas 3a decomposed readily in solution in the absence of free H3GePh, and a pure bulk sample was not obtained. Reactions of 1 with H3GeR′ (R′ = Ph or nBu) also proceeded at 55–60 °C to afford mixtures of 3a/b, 4a/b and 5a/b, accompanied by remaining 1. However, upon continued heating to consume 1, various unidentified manganese-containing intermediates were formed, ultimately affording the germanide complex [{(dmpe)2MnH}2(μ-Ge)] (6) in 17–49% spectroscopic yield. Pure trans,trans-6 was isolated in 27% yield from the reaction of 1 with H3GenBu, and it is notable that this reaction involves stripping of all four substituents from the hydrogermane. Complexes 2a, 3a, and 6 were crystallographically characterized, and the nature of the Mn＝Ge bonding in these species (as well as in 2b and 3b) was probed computationally. [ABSTRACT FROM AUTHOR]

Iso-tellurazole N-oxides are promising supramolecular building blocks. While in neutral solutions, they form tetra-and hexameric macrocyclic aggregates linked by Te ... O secondary bonding (t hole interactions or chalcogen bonds), protonation of the oxygen atom in acidic media disrupts such supramolecular association. The process is reversible and, consequently, can be used to switch on and off the self-assembly process. Hammett acidity measurements gave p[K.sub.a] values of-3.2 for the protonated molecules. Adducts with HCl and HBr were isolated and structurally characterized. Protonation in solution led to the crystallization of a new polymorph of 3-methyl-5-phenyl-1,2- tellurazole N-oxide, which features a unique polymeric arrangement. Key words: sigma-hole interactions, secondary bonding, chalcogens, supramolecular chemistry, main-group chemistry. Les isotellurazoles N-oxydes sont des synthons supramoleculaires prometteurs. Bien qu'en solution neutre, ils forment des agregats macrocycliques tetrameriques et hexameriques retenus par des liaisons secondaires Te ... O (interactions de trous t ou liaisons chalcogene), en milieu acide, la protonation des atomes d'oxygene perturbe une association supramoleculaire de ce type. Ce processus d'association est reversible et peut donc etre utilise pour provoquer ou inhiber le processus d'autoassamblage. Nous avons calcule, pour les molecules protonees, une valeur de p[K.sub.a] de -3,2 derivee des mesures de l'acidite en utilisant l'equation de Hammett. En outre, nous avons isole des adduits de HCl et de HBr et en avons caracterise les structures. La protonation en solution a entraine la cristallisation d'un nouveau polymorphe du 3-methyl-5-phenyl-1,2-tellurazole Noxyde presentant une structure polymerique unique. [Traduit par la Redaction] Mots-cles : interactions de trous sigma, liaison secondaire, chalcogenes, chimie supramoleculaire, chimie du groupement principal., Introduction The remarkable success of halogen bonding (1-4) in areas as diverse as crystal engineering, (2,5-14) supramolecular catalysis, (15) anion recognition, (16) optical materials, (17) and biomimetic chemistry (18-20) has [...]

The secondary bonding interactions that link the supramolecular structures assembled by 1,2,5-chalcogenadiazoles were analyzed through explicit orthogonalization of molecular orbitals (NBO), topological analysis of the electron density (AIM), and the electron localization function (ELF). The results of these analyses are consistent with a bonding description that attributes important covalent and electrostatic character to these interactions. Application of these analyses to the individual molecules highlighted the structural features from which each of those contributions originates, namely the polarity and modest strength of the E-N bond. Both of these effects increase along the series S, Se, Te. Perturbations to the heterocycle electronic structure that result in a weaker and more polar E-N bond cause an increase in the Lewis acidity at the chalcogen centre, which in turn leads to stronger secondary bonding interactions with Lewis bases. Additionally, the contribution of dispersion forces is not negligible and is most important in the case of sulfur. Key words: chalcogenadiazoles, secondary bonding interactions, heterocycles, electronic structure, Lewis acids and bases, computational chemistry. On a analyse les interactions de liaisons secondaires qui unissent les structures supramoleculaires assemblees par les 1,2,5-chalcogenadiazoles en faisant appel a l'orthogonalisation explicite des orbitalesmoleculaires (NBO), a l'analyse topologique de la densite electronique (AIM) et a la fonction de localisation electronique (ELF). Les resultats de ces analyses cadrent avec une description des liaisons attribuant un important caractere covalent ainsi qu'electrostatique a ces interactions. L'application de ces analyses auxmolecules individuelles amis en relief les caracteristiques structurelles a l'origine de ces contributions, a savoir la polarite et la force moderee de la liaison E--N. Ces effets augmentent tous deux le long de la serie S, Se, Te. Les perturbations de la structure electronique de l'heterocycle dues a une liaison E--N plus faible et plus polaire causent une augmentation de l'acidite de Lewis au centre chalcogene, qui a son tour entraine des interactions de liaisons secondaires plus fortes avec les bases de Lewis. En outre, la contribution des forces de dispersion n'est pas negligeable et s'avere etre la plus importante dans le cas du soufre. [Traduit par la Redaction] Mots-cles : chalcogenadiazoles, interactions de liaisons secondaires, heterocycles, structure electronique, acides et bases de Lewis, chimie informatique., Introduction The remarkable tendency of molecules containing the 1,2,5-chalcogenadiazole ring (1) toward self-association has inspired their use as supramolecular building blocks. (1-9) Through the [[E-N].sub.2] (E = S, Se, or [...]

Acetylferrocene readily forms an adduct with B[F.sub.3]. The product is a neutral model for protonated acetylferrocene, a species that is a crucial intermediate in the formation of 1,3,5-trisferrocenyl-benzene and other conjugated heterometallic derivatives by cyclocondensation. The title compound's structure was determined in the solid state by X-ray diffraction and its spectroscopic properties were examined in detail, particularly the electronic excitation spectrum, which confirms the previous identification of the in situ generated protonated ketone. Key words: organometallic ketones, B[F.sub.3] adducts, ferrocenyl cations, density functional theory (DFT) calculations. L'acetylferrocene forme facilement un adduit avec le B[F.sub.3]. Le produit est un modele neutre pour un acetylferrocene, une espece qui est un intermediaire crucial dans la formation du 1,3,5-trisferrocenyl-benzene et d'autres derives heterometalliques par cyclocondensation. La structure du compose mentionne dans le titre a ete determinee a l'etat solide par diffraction des rayons X et on a examine ses proprietes spectroscopiques en detail, en particulier son spectre d'excitation electronique qui confirme l'identification anterieure de la cetone protonee generee in situ. Mots-cles : cetones organometalliques, adduits avec le B[F.sub.3], cations ferrocenyles, calculs d'apres la theorie de la fonctionnelle de la densite (TFD). [Traduit par la Redaction], Introduction Aldehydes and ketones are weak bases, with the typical [pK.sub.a] values of their conjugated acids being below -6, e.g., -6.99 in the case of benzaldehyde and -6.04 for acetophenone. [...]

The structural characterization, magnetic properties and heat capacity of newly synthesized [La.sub.3][Re.sub.2][O.sub.10] are reported. The results indicate that the short-range magnetic ordering might consist of 1-dimensional antiferromagnetic linear chains of coupled S = 1/2 dimers.

Dimethylstannylene (SnMe2) and its subsequent decay to tetramethyldistannene are formed from the 193-nmlaser flash photolysis of 1,1-dimethylstannacyclopent-3-ene in the gas phase and 1,1,3,4-tetramethylstannacyclopent-3-ene in solution. Steady-state photolysis leads to the formation of the corresponding dienes, and in solution, SnMe2 is trapped in reaction with M trimethylstannane (Me3SnH)to afford a product of Sn-H insertion.

The compound [4-C[H.sub.3][C.sub.6][H.sub.4]-SS-C[H.sub.2]C[H.sub.2]-N(C[H.sub.3]) [C.sub.6][H.sub.4]C[([C.sub.6][H.sub.4]N[(C[H.sub.3]).sub.2]-4).sub.2]]Cl (1a) consists of the triarylmethyl chromophore of crystal violet appended to an organic disulfide, to entail direct attachment of this dye to gold surfaces. Addition of 1a to colloidal dispersions of the metal produced a stable dispersion in methanol-water mixtures. Transmission electron microscopy of Freeze-Fracture sections shadowed with carbon and platinum confirmed that the dispersion remains unaggregated. Local-field effects and coupling to the surface plasmon of gold magnified the interaction of the chromophore with optical fields. A large oscillator strength in the visible spectrum (f ca. 35) and a first hyperpolarizability ([beta] ca. [10.sup.-26] esu, hyper-Rayleigh scattering) were observed as the colloid adsorbed dye molecules. A Hill-type analysis indicated that the adsorption process is cooperative. This combination of organic chromophore and nanoparticle was adapted for incorporation into PMMA-based composite films whose electrooptic coefficient ([r.sub.113] = 2.20 pm [V.sup.-1]) is larger than the sum of the individual contributions of dye and metallic particles. Key words: chromophores, colloids, gold, local-field effects, nonlinear optical materials.

Chlorination of 3‐methyl‐5‐phenyl‐1,2‐tellurazole‐2‐oxide yielded the λ4Te dichloro derivative. Its crystal structure demonstrates that the heterocycle retains its ability to autoassociate by chalcogen bonding (ChB) forming macrocyclic tetramers. The corresponding Te⋅⋅⋅O ChB distances are 2.062 Å, the shortest observed to date in aggregates of this type. DFT−D3 calculations indicate that while the halogenated molecule is stronger as a ChB donor it also is a weaker ChB acceptor; the overall effect is that the ChBs in the chlorinated homotetramer are not significantly stronger. However, partial halogenation or scrambling selectively yield the 2 : 2 heterotetramer with alternating λ4Te and λ2Te centers, which calculations identified as the thermodynamically preferred arrangement. [ABSTRACT FROM AUTHOR]

Reduction of 2,1,3-benzotelluradiazole (3) yielded a crystalline solid that features a trimeric dianion formally composed of two [3]˙− and one 3 bridged by unusually asymmetric Te⋯N chalcogen bonds. The solid is diamagnetic due to strong antiferromagnetic coupling, as revealed by CASSCF/CASPT2 and BS-DFT. [ABSTRACT FROM AUTHOR]

The phase that is most stable under ambient pressure and temperature has puckered supramolecular ribbon polymers assembled by Te-N secondary bonding interactions and has disclosed a characteristic red-orange color. Computational DFT studies have shown that the changes in optical properties are related to intermolecular mixing of [pi] orbitals enabled by the supramolecular interactions and the symmetry of the supramolecular synthon.

The use of second-harmonic generation at different wavelengths to compare the resonant contributions of two simple dipolar chromophores, nitroaniline and nitrosulfenamide is reported. The result shows that pi intermolecular interaction does result in excitations that are observable in the linear spectrum of nitroaniline and thus could have an influence on the nonlinear response.

Organochalcogen-nitrogen heterocycles such as the 1,2,5-chalcogenadiazoles have a distinct tendency to establish intermolecular links in the solid state through secondary bonding interactions E...N (E=S, Se, Te). Because of its more polar character and lower-lying antibonding orbitals, the tellerium derivatives possess the strongest association energies.

Laser flash photolysis methods were used to detect and characterize 1,1-diphenylgermylene (Ph2Ge) and its dimer, tetraphenyl digermene in solution. The germylene exhibited a weak long-wavelength UV/vis absorption and dimerized with an absolute rate constant of ca. 1 x 10(super 10)M(super -1)s(super -1) in hexane solution at ambient temperatures to yield 6a.

Research has been conducted on lithium sulfenamides. The preparation of these compounds with alkyllithium is desribed.

The synthesis, and spectroscopic and structural characterization of bridged dicationic derivatives of benzo-2,1,3-selenadiazoles are reported. The chloride salt of [H4C6NSeN–CH2–CH2–NSeNC6H4]2+ crystallizes forming a macrocyclic structure in which two cations are bridged by Se⋯Cl chalcogen bonds (ChBs), with a third chloride at the centre of the macrocycle. The structure of [1,2-(H4C6NSeN)2-C6H10]Cl2 consists of two selenadiazolium cations linked by a chiral cyclohexane and capped by Se⋯Cl ChBs. Tetrafluoroborate salts of a xylene bridge crystallize in two pseudopolymorphs in which the cations form Se⋯F ChBs in an anti- or syn-conformation. The triflate salt of ethylene-bridged cations dimerizes through the formation of the [Se–N]2 supramolecular synthon with Se⋯O ChBs capping the second selenium atom. In contrast, [H4C6NSeN–CH2–CH2–CH2–NSeNC6H4](CF3SO3)2 only forms Se⋯O ChBs. [ABSTRACT FROM AUTHOR]

The reactions of iso-tellurazole N-oxides with monocations of the coinage metals yielded a family of coordination complexes with a remarkable variety of compositions and structures. All new species were identified by single-crystal X-ray diffraction. In all cases, the macrocyclic aggregation of the organo-chalcogen heterocycles through Te⋯O chalcogen bonding interactions is preserved and the metal ions are coordinated by tellurium. Copper and gold formed complexes with the tetramers. The lighter element acquired a κ4Te,κ1O pentacoordinated square pyramidal structure with a triflate anion in the apical position. The preference of the heavier metal for a linear κ1Te,κ1Cl coordination geometry permitted the formation of a binuclear complex. Silver demonstrated a unique preference for coordinating to the hexamer; two distinct examples showed a structure with a pair of endocyclic κ2Te,κ2O metal ions bridged by two triflate anions; the other two chalcogen atoms are located at trans-annular positions and each coordinates a κ1Te,κ1O,κ1C silver ion, also bonded to an aromatic carbon and another triflate anion. [ABSTRACT FROM AUTHOR]

Pt(ii) and Rh(iii) readily form complexes with 3-methyl-5-aryl-1,2-tellurazole 2-oxides (L = (3-Me-5-Ar-1,2-C3HTe(NO)). The aryl group is either phenyl or 3,5-di-tert-butylphenyl, the latter case being a new derivative with enhanced solubility. The compound [Pt(3-Me-5-(3,5-tBu2C6H3)-1,2-C3HTe(NO))4](BF4)2 crystallizes in the P21/C space group featuring a square planar complex in the lattice. The crystal of [RhCl2(3-Me-5-(C6H5)-1,2-C3HTe(NO))4](BF4) belongs to the I4̅ space group and contains an octahedral complex. In both instances, the iso-tellurazole N-oxide molecules are linked by Te…O chalcogen bonding interactions confirming an annular tetramer that binds the metal ion as a κ4Te macrocycle in a boat conformation. Low-frequency shifts of the 125Te magnetic resonance upon coordination and the observation of 125Te–195Pt and 125Te–103Rh 1J coupling constants indicate that the complexes are stable species in solution. The complex ions were also observed in the electrospray mass spectra. [ABSTRACT FROM AUTHOR]

N-Bonded adducts of benzo-2,1,3-selenadiazole with BX3 (X = Ph, F, Cl, Br) were prepared and crystallographically characterized. The structures of the 1 : 1 adducts of BF3 and BCl3 demonstrate dimerization through the [Se–N]2 supramolecular synthon and enhancement of the corresponding Se…N chalcogen bonding interactions. However, the structures of the BPh3 and BBr3 compounds indicate that other supramolecular interactions can efficiently compete and inhibit [Se–N]2 dimerization. In the case of the BPh3 adduct, dispersion favors a dimer featuring Se…C interactions. In the crystal of the BBr3 derivative, the cooperative effect of Se…N chalcogen bonding and Br…Br halogen bonding interactions lead to a network structure. A 1 : 2 adduct could be isolated only in the case of BCl3; its structure features short intramolecular Se…Cl interactions resulting from the enhanced electrophilic character of the chalcogen atom. [ABSTRACT FROM AUTHOR]

The supramolecular macrocycles spontaneously assembled by iso-tellurazole N-oxides are stable towards Lewis bases as strong as N-heterocyclic carbenes (NHC) but readily react with Lewis acids such as BR3 (R = Ph, F). The electron acceptor ability of the tellurium atom is greatly enhanced in the resulting O-bonded adducts, which consequently enables binding to a variety of Lewis bases that includes acetonitrile, 4-dimethylaminopyridine, 4,4′-bipyridine, triphenyl phosphine, a N-heterocyclic carbene and a second molecule of iso-tellurazole N-oxide. [ABSTRACT FROM AUTHOR]

Iodine oxidation of bis[2-(hydroxyiminomethyl)phenyl] dichalcogenides yields benzo-1,2-chalcogenazole 2-oxides. Annulated derivatives of iso-tellurazole N-oxides spontaneously aggregate into cyclic tetra- and hexamers through Te…O chalcogen bonding; the structures of the co-crystals with benzene and CH2Cl2 illustrate the ability of these macrocycles to interact with small guest molecules. The selenium congener crystallizes forming a supramolecular polymer. VT NMR indicates that both compounds aggregate in solution but only at low temperature in the selenium case. The different abilities of these molecules to engage in supramolecular interactions are interpreted on the basis of their electronic properties evaluated with DFT-D3 calculations. [ABSTRACT FROM AUTHOR]

Despite their versatility, the application of telluradiazoles as supramolecular building blocks is considerably constrained by their sensitivity to moisture. Albeit more robust, their selenium analogues form weaker supramolecular interactions. These, however, are enhanced when one nitrogen atom is bonded to an alkyl group. Here we investigate general methods for the synthesis of such derivatives. Methyl, iso-propyl and tert-butyl benzo-2,1,3-selenadiazolium cations were prepared by direct alkylation or cyclo-condensation of the alkyl-phenylenediamine with selenous acid. While the former reaction only proceeds with the primary and tertiary alkyl iodides, the latter is very efficient. Difficulties reported in earlier literature are attributable to the formation of adducts of benzoselenadiazole with its alkylated cations and side reactions initiated by aerobic oxidation of iodide. However, the cations themselves are resilient to oxidation and stable in acidic to neutral aqueous medium. X-ray crystallography was used in the identification and characterization of the following compounds: [C6H4N2(R)Se]+X−, (R = CH(CH3)2, C(CH3)3; X = I−, I3−], [C6H4N2(CH3)Se]+I−, and [C6H4N2Se][C6H4N2(CH3)Se]2I2. Formation of Se…N secondary bonding interactions (chalcogen bonds) was only observed in the last structure as anion binding to selenium is a strong competitor. The relative strengths of those forces and the structural preferences they enforce were assessed with DFT-D3 calculations supplemented by AIM analysis of the electron density. [ABSTRACT FROM AUTHOR]

Bis(imino)acenaphthene (BIAN) zinc complexes with para-substituted aryl groups have been synthesized and investigated from the standpoint of their photophysical properties. Each complex was found to be nonemissive in solution. However, complexes 1–6 turned out to be emissive in the solid state, while complexes 7 and 8 remained nonemissive. The emissions for complexes 1–8 displayed color tunability ranging from red-yellow. A detailed crystallographic study of the “as-synthesized” structures revealed a distinct difference in the crystal packing environments of the emissive and nonemissive complexes. Furthermore, a solvatomorphic study provided further emission tunability via changes in the crystal packing environments of each solvatomorph. Lastly, TD-DFT calculations were performed in order to investigate the effect of different para-substituents on the flanking aryl rings of the BIAN ligand. [ABSTRACT FROM AUTHOR]

The reaction of lithiated picolines and [TiCl3(η5-C5Me5)] leads to several bridging or terminal imido compounds, each of which can be selectively formed by controlling the stoichiometry and temperature. Specifically, the dinuclear imido-bridged [TiCl(η5-C5Me5)(μ-NR)]2 (1a, NR = 2-imido-3-picoline; 1b, NR = 2-imido-5-picoline) species and the unusual Ti–Li imido–amido heterobimetallic complex [{Li(THF)}{Ti(η5-C5Me5)(NR)(NHR)2}] (2a, NR = 2-imido-3-picoline; 2b, NR = 2-imido-5-picoline) were isolated. Compounds 2 are in effect the first structurally characterized examples of titanium(iv) coordinated to terminal imido-pyridines. DFT-D calculations for 2a denote a multiple bond character between titanium and the imido ligand and a strong polarization of the electron density by the alkali cation in spite of the lack of intermetallic bonding. [ABSTRACT FROM AUTHOR]

The products of the combination of benzo-2,1,3-selenenadiazole with chloride salts of divalent Mn, Fe, Co, Ni, and Cd crystallize from DMSO in two distinct structural types. While the smaller ions form infinite chains of metal atoms N,N′-bridged by the heterocycle, the larger ions stabilize infinite chains of metal atoms bridged by μ2 halide ions. In the latter case, two heterocycle molecules cap each metal ion and are able to establish a link to the next chain in the lattice through the [Se–N]2 supramolecular synthon. Despite the large (＞9.2 Å) distance between the [M(μ-Cl)2]∞ chains, the manganese derivative is only paramagnetic. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and theoretical study of the sterically directed functionalization of the redox-active bis(imino)acenaphthene (BIAN) ligand class has been explored. With dependence on the steric congestion encompassing the N-C-C-N fragment of the Ar-BIAN ligand, functionalization can be directed to proceed either via a radical backbone dearomatization or a nucleophilic imine C-alkylation pathway. The structures of the Ar-BIAN derivatives 14-19 were determined by means of single-crystal X-ray diffraction. The reaction pathways involved in Ar-BIAN functionalization were monitored by means of EPR spectroscopy. The experimental results and observations were examined in conjunction with DFT-D calculations in order to explain the driving forces that direct the pathways leading to Ar-BIAN functionalization. [ABSTRACT FROM AUTHOR]

The mass spectra of benzo-2,1,3-chalcogenadiazoles, acquired from the equilibrium conditions of the UV-laser desorption/ionization plume, contain isotopic patterns that are characteristic of protonated and ionized dimers. Dispersion-corrected DFT modeling shows that the most stable structures of these dimers feature the supramolecular four-membered Te2N2 ring, which is pervasive in the crystal structures of these compounds. These observations provide the first evidence of the persistence of Te-N supramolecular association in the gas phase. [ABSTRACT FROM AUTHOR]

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