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Synthesis and Structure of the First Tellurium(III) Radical Cation
Abstract
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
... [27] This is in marked contrast to Roesky's bis(trimethylsilyl)amide tellurium radical cation [{(Me 3 Si) 2 N} 2 Te] * + [AsF 6 ] À , which is not only electronically stabilized by conjugation with the lone pairs at the N atoms, but is also affected by ion pairing. [45] In [1 c] * + [B(C 6 F 5 ) 4 ] À , the individual TeÀ C bond lengths (2.166(1) and 2.179(1) Å, are significantly different and surprisingly, the average value (2.173(1) Å) is somewhat larger than in the neutral parent 1 c (2.150(1) Å. ...
... We note that the TeÀ N bond lengths of [{(Me 3 Si) 2 N} 2 Te] * + [AsF 6 ] À are slightly shorter than in the neutral telluride {(Me 3 Si) 2 N} 2 Te, which was attributed to the conjugation with the lone pairs at the N atoms. [45] The radical cation [1 c] * + was characterized by electron paramagnetic resonance (EPR) spectroscopy. Due to the extremely fast relaxation time, the EPR spectrum of [1 c] * + was not observed in a liquid CH 2 Cl 2 solution at room temperature and was measured in frozen glassy CH 2 Cl 2 at 40 K using CW and spin echo detection modes (see the Supporting Information for details). ...
... A slightly larger level of delocalization of spin density into the ligand system is obtained for the [{(Me 3 Si) 2 N} 2 Te] * + radical cation in an otherwise similar overall SD distribution ( Figure S53d). The ELI-D localization domain representation of [{(Me 3 Si) 2 N} 2 Te] * + unravels two LP-basins, which are still fused at an iso-value of 1.4, mirroring the p z (Te)shaped SD, thereby not supporting the proposed 'rehybridization' [45] Figure S56i). This suggests that the local electronic environment around the Te atom shows stronger effects against one or two electron oxidation than the lighter analogues. ...
Sterically encumbered bis(m‐terphenyl)chalcogenides, (2,6‐Mes2C6H3)2E (E=S, Se, Te) were obtained by the reaction of the chalcogen tetrafluorides, EF4, with three equivalents of m‐terphenyl lithium, 2,6‐Mes2C6H3Li. The single‐electron oxidation of (2,6‐Mes2C6H3)2Te using XeF2/K[B(C6F5)4] afforded the radical cation [(2,6‐Mes2C6H3)2Te][B(C6F5)4] that was isolated and fully characterized. The electrochemical oxidation of the lighter homologs (2,6‐Mes2C6H3)2E (E=S, Se) was irreversible and impaired by rapid decomposition.
... The natural population analysis for 1 mC À predicts a small decrease in the positive charge on the tellurium atom ( % 1.22) compared with 1 m (1. 39), and an increase in the negative charges on the nitrogen and oxygen atoms ( Figure 2, Table 2). The net charge of the arylamidophenoxide group was also calculated as a sum of natural atomic changes and was found to be À0.85 and À1.15 in 1 m and 1 mC À , respectively. ...
... [38] However, to the best of our knowledge, there is only one reliable example of an isolated paramagnetic tellurium compound: Roesky et al. succeeded in isolating the salt [Te{N(SiMe 3 ) 2 } 2 ]AsF 6 , obtained by the oxidation of [Te{N(-SiMe 3 ) 2 } 2 ] with AgAsF 6 , and recording its EPR spectrum as a broad single line without any hyperfine splitting. [39] To better understand the temperature changes in the experimental EPR spectrum, we performed quantum chemical calculations of the spin-Hamiltonian parameters for 1 mC À Relativistic DFT calculations of the HFI tensor for radical anion 1 mC À Unfortunately, information on the A tensors and HFI constants for 125 Te is practically absent. Comasseto et al. succeeded in detection of the EPR spectrum of isotopically substituted ( 125 Te, 92 %) tellurium radical 6 (Scheme 4) and to determine the value of a iso ( 125 Te) = 1.58 mT. ...
Interaction of the tetradentate redox‐active 6,6′‐[1,2‐phenylenebis(azanediyl)]bis(2,4‐di‐tert‐butylphenol) (H4L) with TeCl4 leads to neutral diamagnetic compound TeL (1) in high yield. The molecule of 1 has a nearly planar TeN2O2 fragment, which suggests the formulation of 1 as TeIIL²⁻, in agreement with the results of DFT calculations and QTAIM and NBO analyses. Reduction of 1 with one equivalent of [CoCp2] leads to quantitative formation of the paramagnetic salt [CoCp2]⁺[1].−, which was characterised by single‐crystal XRD. The solution EPR spectrum of [CoCp2]⁺[1].− at room temperature features a quintet due to splitting on two equivalent ¹⁴N nuclei. Below 150 K it turns into a broad singlet line with two weak satellites due to the splitting on the ¹²⁵Te nucleus. Two‐component relativistic DFT calculations perfectly reproduce the a(¹⁴N) HFI constants and A∥(¹²⁵Te) value responsible for the low‐temperature satellite splitting. Calculations predict that the additional electron in 1.− is localised mainly on L, while the spin density is delocalised over the whole molecule with significant localisation on the Te atom (≥30 %). All these data suggest that 1.− can be regarded as the first example of a structurally characterised monomeric tellurium–nitrogen radical anion.
A simple methodology for the synthesis of heteroleptic diorganotelluride [2,6‐(Me2NCH2)2C6H3]TenBu (1) and homoleptic diorganotelluride [2,6‐(Me2NCH2)2C6H3]2Te (2) is reported. The halogenation reactions of diorganotelluride 1 are studied. In particular, the reaction of 1 with Br2 resulted in the isolation of a monoorgano dibromotelluronium(IV) cation, namely [2,6‐(Me2NCH2)2C6H3TeBr2]·Br3 ([3]·Br3). The reaction of [3]·Br3 with K2PdCl4 afforded a monoorgano mixed dihalotelluronium(IV) cation, [2,6‐(Me2NCH2)2C6H3TeClBr]·PdBr4 ([4]·PdBr4). When diorganotelluride 1 was treated with I2, the reaction afforded the tellurenium(II) cation, [2,6‐(Me2NCH2)2C6H3Te]·I2·I3 ([5]·I2·I3). The reaction of 1 with HgCl2 resulted in the isolation of dimeric diorganoditelluroxonium(IV) cation, [2,6‐(Me2NCH2)2C6H3Te(µ‐O)]2·Hg2Cl6 ([6]·Hg2Cl6). A similar diorganoditelluroxonium(IV) cation, namely [2,6‐(Me2NCH2)2C6H3Te(µ‐O)]2·2Br ([6]·2Br) was also obtained by the reaction of 1 with Br2 and NaOH. The crystallographic studies suggest that for each compound, both the N atoms from the pendant arms make strong Intramolecular Chalcogen Bonding (IChB) interactions with the Te center(s). The presence of a strong N→Te IChB interaction in the synthesized compounds was further validated by DFT calculations.
Chemistry and materials science of Herz radicals (1,2,3-benzodichalcogenazolyls; chalcogen is S or Se) are discussed including their synthesis, structure and reactivity. Preparation and functional characterization of radical-based molecular conducting and magnetic materials are considered.
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...
The reactivity of the chalcogen–nitrogen bond toward main-group element or transition-metal halides, as well as electrophilic and nucleophilic reagents, is the source of a variety of applications of Se–N and Te–N compounds in both inorganic or organic chemistry. The thermal lability of Se–N compounds also engenders useful transformations including the formation of radicals via homolytic Se–N bond cleavage. These aspects of Se–N and Te–N chemistry will be illustrated with examples from the reactions of the binary selenium nitride Se 4 N 4 , selenium–nitrogen halides [N(SeCl n ) 2 ] ⁺ ( n = 1, 2), the synthons E(NSO) 2 (E = Se, Te), chalcogen–nitrogen–silicon reagents, chalcogen(IV) diimides RN=E=NR, the triimidotellurite dianion [Te(N t Bu) 3 ] ²⁻ , chalcogen(II) amides and diamides E(NR 2 ) 2 (E = Se, Te; R = alkyl, SiMe 3 ), and heterocyclic systems.
By means of cyclic voltammetry (CV) and DFT calculations, it was found that the electron‐acceptor ability of 2,1,3‐benzochalcogenadiazoles 1–3 (chalcogen: S, Se, and Te, respectively) increases with increasing atomic number of the chalcogen. This trend is nontrivial, since it contradicts the electronegativity and atomic electron affinity of the chalcogens. In contrast to radical anions (RAs) [1].− and [2].−, RA [3].− was not detected by EPR spectroscopy under CV conditions. Chemical reduction of 1–3 was performed and new thermally stable RA salts [K(THF)]⁺[2].− (8) and [K(18‐crown‐6)]⁺[2].− (9) were isolated in addition to known salt [K(THF)]⁺[1].− (7). On contact with air, RAs [1].− and [2].− underwent fast decomposition in solution with the formation of anions [ECN]⁻, which were isolated in the form of salts [K(18‐crown‐6)]⁺[ECN]⁻ (10, E=S; 11, E=Se). In the case of 3, RA [3].− was detected by EPR spectroscopy as the first representative of tellurium–nitrogen π‐heterocyclic RAs but not isolated. Instead, salt [K(18‐crown‐6)]⁺2[3‐Te2]²⁻ (12) featuring a new anionic complex with coordinate Te−Te bond was obtained. On contact with air, salt 12 transformed into salt [K(18‐crown‐6)]⁺2[3‐Te4‐3]²⁻ (13) containing an anionic complex with two coordinate Te−Te bonds. The structures of 8–13 were confirmed by XRD, and the nature of the Te−Te coordinate bond in [3‐Te2]²⁻ and [3‐Te4‐3]²⁻ was studied by DFT calculations and QTAIM analysis.
This review provides an overview of the precursor chemistry that has been developed around the phase-change material germanium-antimony-telluride, Ge2Sb2Te5 (GST). Thin films of GST can be deposited by employing either chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques. In both cases, the success of the layer deposition crucially depends on the proper choice of suitable molecular precursors. Previously reported processes mainly relied on simple alkoxides, alkyls, amides and halides of germanium, antimony, and tellurium. More sophisticated precursor design provided a number of promising new aziridinides and guanidinates.
In this brief review, synthesis, structural and reactivity aspects of heavier organochalcogen (RS+n, RSe+n, RTe+n;n = 1–3) cations have been described. The orgaosulfenium ions (RS+) and related sulfur cations have been already reported in detail and, therefore, will not be discussed here. Structurally characterised organochalcogen cations of heavier chalcogens (Se, Te) will be the main focus of the review and only a few relevant examples, which are not structurally characterized, will be discussed for comparison purposes. The collection of chalcogen cations enlisted here shall benefit the readers who are interested in isolating and utilizing the organochalcogen cations for particular applications.
The reaction of tBuNHLi with TeCl4 in toluene at -78 °C produces tBuNTe(μ-NtBu)2TeNtBu (1) (55%) or [(tBuNH)Te(μ-NtBu)2TeNtBu]Cl (2) (65%) for 4:1 or 7:2 molar ratios, respectively. The complex {Te2(NtBu)4-[LiTe(NtBu) 2(NHtBu)]LiCl}2 (5) is obtained as a minor product (23%) from the 4:1 reaction. It is a centrosymmetric dimer in which each half consists of the tellurium diimide dimer 1 bonded through an exocyclic nitrogen atom to a molecule of LiTe(NtBu)2(NHtBu) which, in turn, is linked to a LiCl molecule. Crystals of 5 are monoclinic, of space group C2/c, with a = 27.680(6) Å, b = 23.662(3) Å, c = 12.989(2) Å, β = 96.32(2)°, V = 8455(2) Å3, and Z = 4. The final R and RW values were 0.046 and 0.047. At 65 °C in toluene solution, 5 dissociates into 1, LiCl and {[LiTe(NtBu)2(NHtBu)]2LiCl} 2 (4), which may also be prepared by treatment of [Li2Te(NtBu)3]2 (6) with 2 equiv of HCl gas. The centrosymmetric structure of 6 consists of a distorted hexagonal prism involving two pyramidal Te(NtBu)32- anions linked by four Li atoms to give a Te2N6Li4 cluster. Crystals of 6 are monoclinic of space group P21/c, with a = 10.194(2) Å, b = 17.135(3) Å, c = 10.482(2) Å, β= 109.21(1)°, V = 1729.0(5) Å3 and Z = 2. The final R and RW values were 0.026 and 0.023. VT 1H and 7Li NMR studies reveal that, unlike 1, compounds 2,4, and 6 are fluxional molecules. Possible mechanisms for these fluxional processes are discussed.
This chapter provides an account of the chemistry of neutral and charged radicals that incorporate the heavier p-block elements, primarily from groups 13 to 15, as well as boron-containing radicals. The emphasis is on stable radicals that can be isolated and structurally characterized in the solid state; however, persistent radicals are also included, especially when they have important applications, for example, in organic synthesis or as polymerization initiators. Although the different synthetic approaches to individual radical systems are mentioned briefly, the main focus of the discussion is on the information that is provided about the molecular and electronic structures of main-group element radicals by x-ray structural determinations, electron paramagnetic resonance spectroscopic investigations, and theoretical calculations.
The first investigations of coordination complexes of the tellurium diimide dimer [tBuNTe(μ-NtBu)]2 (1a) are presented. The coinage metals Ag+ and Cu+ were chosen to evaluate the ability of 1a to function as a chelating or bridging ligand. Reaction of 1a with Ag[O3SCF3] in toluene produces [Ag2L2][O3SCF3]2 (5, L = 1a) or, in the presence of LiCl, [Ag2L2(μ-Cl)][O3SCF3] (3). In 4 the two Ag+ ions bridge two molecules of cis-1a and engage in a weak Ag···Ag bonding interaction. In 3 the Cl- ion bridges two Ag+ ions, which are each chelated to the terminal NtBu groups of 1a. Treatment of 1a with Cu[O3SCF3] in toluene yields {[CuL][CF3SO3]}n (5) which, in turn, reacts with 1a to form [Cu2L3][CF3SO3]2 (6). In 6 the two Cu+ ions bridge cis and trans forms of 1a. The hydrolysis products {[tBuNTe(μ-NtBu)2Te(μ-O)]2[M(H2NtBu)]2}[O3SCF3]2 (7a, M = Ag; 7b, M = Cu) and [Cu2L(tBuNH2)2][O3SCF3]2 (8) were also structurally characterized. The complexes 7a,b contain the dimer [tBuNTe(μ-NtBu)2(μ-O)]2 in which one of the terminal NtBu ligands in 1a is replaced by an O atom. The central Te2O2 ring in this spirocyclic ligand is planar with unsymmetrical oxygen bridging [d(Te−O) = 1.885(7) and 2.170(7) Å in 7b]. The ligand 1a in 8 is in the trans conformation. Mono- or dimethylation of 1a with CF3SO3Me was shown to occur at the terminal nitrogens by 1H and 125Te NMR spectroscopy.
This review examines the role that the bis-trimethylsilylamido group, [N{SiMe3}2]–, has had on the development of the chemistry of the metallic elements of the p-block. Key historic milestones are summarized, with the focus of the report on the structural aspects that this ligand plays on compounds reported in the last 15 years. It is preceded by article reviewing the structural chemistry of the bis-trimethylsilylamido ligand in association with the s-block metals.
The reaction of 2,3-diaminomaleonitrile with TeX4 (X = Cl, Br) in the presence of pyridine (Py) and/or triethylamine (Et3N) provided 3,4-dicyano-1,2,5-telluradiazole (1), which was isolated neat and as stable adducts with pyridine, chloride, and bromide, namely, 1·2Py, (PyH)(1·Cl), (PyH)2(1·2Cl), (Et3NH)(1·Cl), (PyH)(1·Br), and (PyH)2(1·2Br). The molecular and supramolecular structures of these compounds were investigated by X-ray crystallography. In the solid state, intermolecular associations through secondary Te···N interactions as well as N–H···X and N–H···N hydrogen bonding (X = Cl, Br) were observed. For (PyH)(1·Br), two polymorphs were found. The bonding situation of 1 and its pyridine and chloride adducts were investigated by MP2 calculations supplemented with the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The π symmetry of the frontier molecular orbitals (MOs) of 1 are preserved in the 1·2Py, (1·Cl–), and (1·2Cl–) adducts. In the chloride adducts, the highest occupied molecular orbital (HOMO) can be described as an antibonding combination of the HOMO of 1 with the 3p atomic orbitals (AOs) of the chloride ions, whereas the lowest occupied molecular orbital (LUMO) resembles that of the parent 1. The charge transfer onto the heterocycle in the adducts increases in the order 1·2Py, (1·2Cl–), and (1·Cl–). QTAIM analyses of the adducts in the gas phase reveal closed-shell interactions, whereas NBO analyses indicate negative hyperconjugation as the main formation pathway in these complexes. This description agrees with the Alcock model suggested for secondary bonding interactions between atoms of heavy p-block elements and atoms with lone pairs.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Reactions of disodium salt of the ligands 4,5-dimercapto-1,3-dithiole-2-thione [H2(dmit)] and 4,5-dimercapto-1,2-dithiole-3-thione [H2(dmt)] with “sodium selenopentathionate”-3-hydrate [Na2Se(S2O3)2]·3H2O and “sodium telluropentathionate”-2-hydrate [Na2Te(S2O3)2·2H2O, in the presence of cations Me3Te+, Ph4As+, (C5H5)2Co+ and PPN+, yielded the corresponding complexes of stoichiometry [cation]2[M(dmit)2] and [cation]2[M(dmt)2]2 (M = Se or Te). These complexes are thermally unstable and undergo redox decomposition in solution. Oxidation reactions of these complexes with iodine or tetracyanoquinodimethane afforded sulphocarbon C6S10. In order to study the oxidation-reduction process of these complexes, detailed electrochemical investigations have been carried out.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The development of bulky monodentate alkoxide, chalcogenolate (ER, E = S, Se or Te), amide, pnictide (ER2 = N, P, As), alkyl, aryl and silyl ligands is briefly surveyed. These ligands have played a key role in the advancement of the modern organometallic and inorganic chemistry of all the major blocks (s, p, d, and f) of the periodic table. Most importantly, they have permitted numerous new classes of compounds to be isolated and studied. The investigation of steric effects induced by these ligands has led to, inter alia, transition metal alkylidene and alkylidyne complexes, room temperature cleavage of dinitrogen, and a wide range of transition metal and lanthanide complexes with two or three coordination. In addition, their use has sparked a revolution in main group chemistry which has led to the isolation of stable species with bonds and/or oxidation states hitherto unknown in stable compounds.
NO und O2liefern das Sauerstoffatom für die dikationischen µ-Oxo(diaryltellurium)-Dimere 2 (X = BF4− bzw. CF3SO3−), die durch chemische Oxidation von 1 mit NOBF4 bzw. mit (CF3SO2)2O/O2 entstehen [Gl. (a)]. Das Schicksal des Stickstoffatoms aus dem Oxidationsmittel NOBF4 ist noch unklar.
Keinesfalls explosiv wie so manche Te‐N‐Verbindung ist das Li 2 ‐Derivat des Tris( tert ‐butylimido)tellurit‐Dianions 1 , das aus [( t BuN)Te] 2 ( μ ‐N t Bu) 2 und t BuNHLi hergestellt werden kann. In der Struktur von 1 liegt ein verzerrt hexagonaler, prismenförmiger Te 2 N 6 Li 4 ‐Käfig vor. Setzt man 1 mit PhPCl 2 oder PhBCl 2 um, so entsteht der Spirocyclus 2 bzw. der Vierring 3 . magnified image
Amphoteric tellurium‐containing π‐donors'acceptors are reported. The electrical and magnetic properties of the charge‐transfer complexes and radical cation salts prepared from 1 (see Figure; X Te, R ¹ Me) are presented. 1 exhibits a remarkably low oxidation potential compared with S analogues and a one‐step two‐electron reduction potential, indicating that its derivatives could also be of use as the first Te‐containing organic electron acceptors. magnified image
The methods available for the synthesis of selenium-nitrogen (Se-N) heterocycles are discussed. The chemistry of phosphorus-containing Se-N and Te-N ring systems is described and compared with that of the corresponding S-N heterocycles. The P2N4Se2 ring is a versatile ligand in transition-metal complexes. The use of Se NMR and ESR spectroscopy in the characterization of cyclic Se-N systems is also presented.
Condensation of the highly reactive complex [{Te(NMe2)2}∞]1, prepared by the reaction of TeCl4 and Li[NMe2](1 : 4 equivalents), with various organic acids has been used as a route to tellurium(II) metalloorganic complexes. The crystal structures of 1 and of Te(SCPh3)22, formed by the reaction of 1 with Ph3CSH(1 : 2 equivalents), have been determined.
Tellurium compounds of the main-group elements are attracting increasing attention as potential single-source precursors for binary tellurides that have desirable properties for applications in the electronics and related industries. In addition, many tellurium compounds exhibit unique structures that are of fundamental interest and multiply-bonded derivatives often display unusual reactivity. Recent progress and future prospects in these three aspects of tellurium chemistry are discussed. The cover picture shows the structure of the spirocyclic tellurium(IV) compound Ph(Bu(t)N)P(mu-NBu(t))(2)Te(mu-NBu(t))(2)P(NBu(t))Ph, which is prepared by the reaction of the novel cluster [{Li2Te(NBu(t))(3)}(2)] with 2 equivalents of PhPCl(2).
NO and O2molecules are the source of the oxygen atom for dicationic µ-oxo(diaryltellurium) dimers 2 (X=BF4−, CF3SO3−), which form upon chemical oxidation of 1 with NOBF4 (method A) or (CF3SO2)2O/O2 [method B, Eq. (a)]. The fate of the nitrogen atom of the oxidizing agent NOBF4 remains uncertain at this stage.
Die Titelverbindung entsteht durch Reaktion von Tellurtetrachlorid mit Tris(trimethylsilyl)amin in siedendem Toluol. Blaßgelbe Kristalle der Zusammensetzung [Te11N6Cl26]2 · 9C7H8 entstehen beim Abkühlen gesättigter Lösungen. Die Verbindung wird durch das IR-Spektrum und durch eine Kristallstrukturanalyse charakterisiert. Raumgruppe P1, Z = 1, Strukturlösung mit 5912 beobachteten unabhängigen Reflexen, R = 0,043. Gitterkonstanten bei −50°C: a = 1636,2; b = 1692,7; c = 1704,1 pm; α = 60,57 β = 69,59°; γ = 64,29°. Bestimmendes Strukturmotiv des Nitridchlorids sind planare Te5N3-Einheiten, die zwei miteinander kondensierte Te2N2-Viererringe bilden. Zwei asymmetrische Einheiten [Te11N6Cl26] sind über ein Symmetriezentrum miteiander verknüpft; die eingelagerten Toluomoleküle sind ohne bindende Wechselwirkung.Synthesis and Crystal Structure of the Tellurium Nitride Chloride [Te11N6Cl26]The title compound has been prepared by the reaction of tellurium tetrachloride with tris(trimethylsilyl)amine in boiling toluene. Pale yellow crystals of the composition [Te11N6Cl26]2 · 9C7H8 are obtained by cooling of the saturated solution. The compound was characterized by IR spectroscopy and by a crystal structure determination. Space group P1, Z = 1, structure solution with 5912 observed unique reflections, R = 0.043. Lattice dimensions at −50°C: a = 1636.2, b = 1692.7, c = 1704.1 pm, α = 60.57°, β = 69.59°, γ = 64.29°. The dominating structural element of the nitrchloride are planar Te5N3 units forming two four-member Te2N2 rings which are condensed together. Two asymmetric units [Te11N6Cl26] are linked by a centre of symmetry; the intercalated toluene molecules are without binding interactions.
A nonexplosive, easy-to-handle TeN reagent is the Li2 derivative of the tris(tert-butylimido)tellurite dianion 1, which can be prepared from [(tBuN)Te]2(μ-NtBu)2 and tBuNHLi. The Te2N6Li4 cage in 1 adopts a distorted hexagonal prismatic structure. The reaction of 1 with PhPCl2 or PhBCl2 produces the spirocycle 2 and the four-membered ring 3, respectively.
Dithia- and diselena-diazolyl radicals (HCN2E2 E = S, Se) and dimers are important building blocks in the design of low-dimensional molecular conductors. Research on the tellurium-based analogues is much rarer. This work reports the molecular and electronic structures of the cation, radical, and radical dimers of 1,2,3,5-ditelluradiazolyl using ab initio theory including electron correlation by Møller–Plesset perturbation theory up to partial fourth order (MP4SDQ). A face-to-face C2v dimer is predicted to be bound with respect to two radicals by approximately 18 kcal/mol. A C2h, dimer also has been studied and is ca. 2 kcal/mol less stable than the C2v conformer. Relaxing symmetry constraints on the dimers led to more energetically stable structures at the Hartree–Fock level but the C2v structure remains the most stable at a level of theory including electron correlation effects. The results for the Te compounds along with our earlier research on the S and Se analogues provide predictions for the geometries, vibrational frequencies, and ionization potentials for the Te species to assist in future experiments. Key words: tellurium, ab initio, ditelluradiazolyl, dimers, binding.
This paper summarizes developments in the synthesis, structural characterization and reactions of tellurium-nitrogen compounds that have occurred during the last five years.
Complexes of empirical formula M[P(SiMe3)2]2 are prepared in 68-90% yields from M[N(SiMe3)2]2 and HP(SiMe3)2 (M = Zn (1), Cd (2), Hg (3), Sn (4), Pb (5), Mn (6)). All of 1-6 are crystalline, air-sensitive, hydrocarbon-soluble solids. Compounds 1 and 2 sublime at 140-degrees-C and 10(-4) Torr. Compound 6 crystallizes as a THF adduct (6.THF); the THF ligand is easily removed in vacuo. X-ray crystallography reveals that 1-3 and 5 are solid-state dimers having the structure {M[P-(SiMe3)2][mu-P(SiMe3)2]}2 and that 6.THF has the structure [(Me3Si)2P]Mn[mu-P(SiMe3)2]2Mn[P(SiMe3)2](THF). The phosphido bridges are symmetric in 1, 2, 5, and 6 and asymmetric in 3; the longer bridge distance in 3 (3.246 (1) angstrom is a secondary bond. The compounds are also dimeric in solution except for 3, which is monomeric. Compounds 1 and 2 undergo bridging-to-terminal site exchange. The barriers calculated from the P-3{H-1} NMR coalescence points are DELTAG not-equal 360 = 14.3 (2) kcal/mol and DELTAG double dagger 321 = 12.7 (6) kcal/mol for 1 and 2, respectively. The barriers calculated from the H-1 NMR coalescence points are DELTAG not-equal 281 = 14.8 (1) kcal/mol and DELTAG double dagger 246 = 12.4 (1) kcal/mol for 1 and 2, respectively. Compounds 4 and 5 exhibit trans reversible cis equilibria in solution; 5 crystallizes as the cis isomer. The thermodynamic quantities for the trans reversible cis equilibria derived from NMR measurements arc DELTAH = -1.8 (1) kcal/mol and DELTAS = -4.7 (2) eu for 4 and DELTAH = -1.4 (1) kcal/mol and DELTAS = -4.4 (2) eu for 5. In general, the P(SiMe3)2 complexes exhibit higher molecularities and higher coordination numbers than the homologous N(SiMe3)2 complexes, which indicates that P(SiMe3)2 ligands have stronger bridging tendencies than do N(SiMe3)2 ligands. The differing behaviors of the two ligands are ascribed to periodic trends that distinguish the properties of N and P. Crystal data for 1: triclinic, P1BAR, a = 9.831 (2) angstrom, b = 10.813 (2) angstsrom, c = 12.692 (3) angstrom, alpha = 80.97 (3)degrees, beta = 67.62 (3)degrees, gamma = 80.20 (3)degrees, V = 1223.1 (4) angstrom3, T = 22-degrees-C, Z = 1. Crystal data for 2: triclinic, P1BAR, a = 9.749 (3) angstrom, b = 10.879 (3) angstrom, c = 13.078 (4) angstrom, alpha = 92.29 (2)degrees, beta = 112.93 (2)degrees, gamma = 98.19 (2)degrees, V = 1257.4 (6) angstrom3, T = 22-degrees-C, Z = 1. Crystal data for 3: triclinic, P1BAR, a = 9.817 (2) angstrom, b = 12.216 (2) angstrom, c = 12.968 (3) angstsrom, a = 61.94 (1)degrees, beta = 67.99 (1)degrees, gamma = 68.53 (2)degrees, V = 1237.6 (4) angstrom3, T = 22-degrees-C, Z = 1. Crystal data for 5: orthorhombic, P2(1)2(1)2(1), a = 13.154 (7) angstrom, b = 18.343 (13) angstrom, c = 20.622 (7) angstrom, V = 4976 (5) angstsrom, T = 22-degrees-C, Z = 4. Crystal data for 6.THF: triclinic, P1BAR, a = 10.107 (3) angstrom, b = 16.581 (4) angstrom, c = 17.234 (4) angstrom, alpha = 85.74 (2)degrees, beta = 82.46 (2)degrees, gamma = 72.12 (2)degrees, V = 2723.2 (12) angstrom3, T = 22-degrees-C, Z = 2.
The reaction of tBuNHLi with TeCl4 in toluene at −78 °C produces tBuNTe(μ-NtBu)2TeNtBu (1) (55%) or [(tBuNH)Te(μ-NtBu)2TeNtBu]Cl (2) (65%) for 4:1 or 7:2 molar ratios, respectively. The complex {Te2(NtBu)4[LiTe(NtBu)2(NHtBu)]LiCl}2 (5) is obtained as a minor product (23%) from the 4:1 reaction. It is a centrosymmetric dimer in which each half consists of the tellurium diimide dimer 1 bonded through an exocyclic nitrogen atom to a molecule of LiTe(NtBu)2(NHtBu) which, in turn, is linked to a LiCl molecule. Crystals of 5 are monoclinic, of space group C2/c, with a = 27.680(6) Å, b = 23.662(3) Å, c = 12.989(2) Å, β = 96.32(2)°, V = 8455(2) Å3, and Z = 4. The final R and Rw values were 0.046 and 0.047. At 65 °C in toluene solution, 5 dissociates into 1, LiCl, and {[LiTe(NtBu)2(NHtBu)]2LiCl}2 (4), which may also be prepared by treatment of [Li2Te(NtBu)3]2 (6) with 2 equiv of HCl gas. The centrosymmetric structure of 6 consists of a distorted hexagonal prism involving two pyramidal Te(NtBu)32- anions linked by four Li atoms to give a Te2N6Li4 cluster. Crystals of 6 are monoclinic, of space group P21/c, with a = 10.194(2) Å, b = 17.135(3) Å, c = 10.482(2) Å, β = 109.21(1)°, V = 1729.0(5) Å3, and Z = 2. The final R and Rw values were 0.026 and 0.023. VT 1H and 7Li NMR studies reveal that, unlike 1, compounds 2, 4, and 6 are fluxional molecules. Possible mechanisms for these fluxional processes are discussed.
In the last three decades the field of the traditionally more exotic selenium nitrogen and tellurium nitrogen compounds has developed considerably. This review presents some of the recent results with a focus on crystal structures. The application of nitrogen NMR spectroscopy will be illustrated as an additional useful tool for the characterization of SeN and TeN materials. This chapter includes newer results on binary, ternary, organoselenium and organotellurium amides, imides, azides and other classes of compounds divided into the different oxidation states of selenium and tellurium. Furthermore, the latest selenium and tellurium nitrogen-containing carbocycles will be mentioned.
Keywords:
selenium;
tellurium;
nitrogen;
molecular structure;
nitrogen NMR spectroscopy
IntroductionGroup 13 element radicalsGroup 14 element radicalsGroup 15 element radicalsGroup 16 element radicalsGroup 17 element radicalsSummary and future prospectsReferences
IntroductionStandard Redox Potentials and Complementary ReferencesReductantsOxidantsElectron-transfer-chain (ETC) CatalysisRedox CatalysisSensorsConclusion
Experimental: Syntheses of the Electron-reservoir Complexes
Synthesis and Structure of the First Tellurium-Containing Borazine Derivative and a Tellurium-Containing Boron – Nitrogen Spirocyclic Compound
We describe the synthesis of the first tellurium-containing borazine derivative MeN[PhBN(Me)]2TeCl2 (2). Compound 2 has been prepared by the reaction of MeN[PhBN(Me)SiMe3]2 and TeCl4. The spirocyclic compound [PhB(tBuN)2]2Te (4) has been synthesized by the reaction of PhB(tBuNLi)2 (3) with TeCl4 in a molar ratio of 2:1. The single-crystal X-ray structures of 2 and 4 are reported.
The results of recent developments in tellurium- and selenium-nitrogen chemistry are presented with emphasis on the preparation, characterization and properties. Wherever possible, the chemistry of cyclic compounds is separated from acyclic species, which are classified according to their oxidation state. Besides conventional methods, e.g. the metathetical reaction between TeX4 (X = F, Cl) or SeX4 (X = Cl) and silylamines such as [R3Si)nNR3-n or R3SiNSNSiR3 etc., two synthons X(NSO)2 (X = Se, Te) that play an important role in Se-N, Te-N and S-N heterocyclic chemistry are described here. For a better understanding, possible reaction pathways for synthesis with Te(NSO)2 or Se(NSO)2 are discussed and evidence for these mechanisms is provided. Attention is also paid to compounds with SeN double bonds. Carbon-, phosphorus- and metal-containing Se-N as well as Te-N heterocycles are dealt with rather restrictively. Vibrational, mass spectroscopic and NMR data are given for important molecules.
The topic of ligand exchange and reaction mechanisms of fluorinated compounds is reviewed, with emphasis on the main group fluorides. Mechanisms are divided into a series of elementary steps of bond formation and bond dissociation, using the coordination model of reaction mechanisms as an organizing principle. Included in this review is an analysis of the stercochemical behavior of pentacoordinated molecules, as well as a discussion of the role of impurities, anionie, cationie, free radical and fluorine-bridged intermediates, and fluoride-induced reactions.
A wide range of radicals in which the unpaired electron is located primarily on a main-group element other than C, N, O or S can be generated as persistent species. Furthermore, a growing number of these can be isolated in the solid state as stable compounds. At present, the crystal structures of approximately two dozen stable or isolable radicals have been determined. A notable feature of the recent work has been the extension of the persistent or stable radical domain to the heavier group 13 elements Al, Ga, or In. In most cases, stabilization has been achieved with use of sterically encumbering ligands and/or delocalization.
A blue luminescent tetradecavanadate compound, [Et4N]5[V14O36Cl], has been synthesized. It possesses an unprecedented half-open basket framework. Through the {ABAB}-type stacking, the {V14O36} clusters form infinite one-dimensional channels with considerable accessible volume in the crystalline state.
Commentary on errors in an earlier article on the nature of the chemical bond. Keywords (Audience): First-Year Undergraduate / General
Erst bei 207°C zersetzt sich 1! Bisher war kein Tellurnitrid bekannt, das auch nur bei Raumtemperatur stabil wäre. 1 entsteht aus TeCl 4 und Me 3 SiN = S = NSiMe 3 in Toluol und kristallisiert aus Dimethylformamid mit drei Solvensmolekülen. Das Ergebnis der Röntgenstrukturanalyse ist rechts gezeigt (ohne DMF‐Moleküle). magnified image
Interaction of LiR [R = CH(SiMe3)2 or N(SiMe3)2] and MCl3 in appropriate stoicheiometry affords the following new compounds: M[CH(SiMe3)2]Cl2 or M[CH(SiMe3)2]2Cl (M = P, As, or Sb), M[N(SiMe3)2]Cl2 or M[N-(SiMe3)2]2Cl (M = As or Sb), or Bi[N(SiMe3)2]3. Reaction of P(NPri2)Cl2 with Li[N(SiMe3)2]·OEt2, Li[N(CMe3)(SiMe3)], Li[CH(SiMe3)2], MgButBr, or NHPri2 yields the corresponding new compound P(NPri2)RCl, while Li[CH(SiMe3)2] with P(NMe2)Cl2 affords P[CH(SiMe3)2](NMe2)Cl. Reduction of the appropriate phosphorus(III) or arsenic(III) monochloride in toluene by photolysis with the olefin (Et[graphic omitted]Et gives the persistent (t½= 3 days to > 1 year in PhMe at 300 K) phosphorus(II) or arsenic(II) alkyl or amide: ·M[CH(SiMe3)2]2(M = P or As), ·M[N(SiMe3)2]2, ·P[CH(SiMe3)2](NR2)(R = Pri or SiMe3), ·P(NPri2)[N(SiMe3)2], ·P[N(CMe3)(SiMe3)]2, or ·P(NPri2)[N(CMe3)(SiMe3)]. Electron spin resonance parameters are discussed.
Reaction of Te3N2SCl2 with cis-PtCl2(PMe2Ph)2 and 1,8-diazabicylo[5.4.0] undec-7-ene provides the first route to a metal-te
Synthesis and Stucture of a Four-Membered Tellurium-Nitrogen Ring
Reaction of Ph3P NSiMe3 (1) with TeCl4 leads to (Ph3P NTeCl3)2 (3). Single crystals of 3 were obtained by recrystallization from CH2Cl2; they contain two molecules of solvent. 3 forms a four-membered planar Te2N2 ring with alternating TeN bonds.
The compound 1 first decomposes at 207°C! It is thus the first tellurium nitride that is stable at room temperature. 1 is formed from TeCl4 and Me3SiNSNSiMe3 in toluene and crystallizes from dimethylformamide with three solvent molecules. The result of the X-ray structure analysis is shown on the right (without DMF molecules).
The new compounds Se[N(SiMe3)2]2 and Te[N(SiMe3)2]2 have been prepared in relatively good yields and their crystal structures determined by X-ray crystallography at low temperatures. The Se compound crystallizes in the monoclinic system, space group C2/c, with Z = 4 and unit cell dimensions a = 1705.4 (3) pm, b = 642.2 (2) pm, c = 2116.7 (4) pm, and beta = 108.19 (2)degrees. The Te compound crystallizes in the triclinic system, space group P1BAR, with Z = 2 and unit cell dimensions a = 903.9 (3) pm, b = 1111.7 (4) pm, c = 1241.0 (4) pm, alpha = 88.67 (2)degrees, beta = 73.68 (3)degrees, and gamma = 69.10 (2)degrees. The crystals of both compounds consist of isolated Ch[N(SiMe3)2]2 (Ch = Se, Te) molecules containing V-shaped ChN2 units with Se-N distances of 186.9 (2) pm and Te-N distances of 205.3 (2) and 204.5 (2) pm. The NChN bond angles were found to be 108.0 (1) and 105.8 (1)degrees for the Se and Te compounds, respectively. No significant intermolecular Ch...N interactions were found in the two compounds, but an intermolecular Te...Te distance of 377 pm, substantially less than the corresponding van der Waals distance, is present in the Te compound.
The mercurial compound Hg[N(CF3)SF5]2 can be obtained in over 95% yield from the direct reaction of SF5N=CCl2 with excess HgF2 at 150°C. X-ray crystal structure analysis of the tellurium analogue Hg[N(CF3)TeF5]2 reveals a linear N-Hg-N arrangement as well as a planar framework around each nitrogen [〈TeNC =119 (2)°]. C2F16N2HgTe2 crystallizes in the orthorhombic space group Pbca. Unit cell parameters: a = 10.746 (5) Å, b = 9.702 (6) Å, c = 12.718 (8) Å, Z = 4; R = 0.090, Rw = 0.101. Reactions of Hg[N(CF3)SF5]2 with halogens or interhalogens give the series of tertiary amines SF5N(X)CF3, where X = F, Cl, Br, and I. Of these only the N-iodo compound is unstable at room temperature. The successful syntheses of SF5N(CH3)CF3 and TeF5N(CH3)CF3 from the respective mercurial compound and CH3I allow the comparison of the relative group electronegativities of SF5N(CF3)- and TeF5N(CF3)- with (CF3)2N-, (CF3S)2N-, (SF5)2N-, (CF3SO2)2N-, and (FSO2)2N-. The new perfluorinated tertiary amine (SF5)2NCF3 is prepared in high yield from the gas-phase photolysis of SF5N(Cl)CF3. The bromoamine SF5N(Br)CF3 adds readily to the alkenes C2H4 and C3F6 to give SF5N(CF3)CH2CH2Br and the mixture of isomers SF5N(CF3)CF2CF(Br)CF3 and SF5N(CF3)CF(CF3)CF2Br, respectively.
With H2N-TeF5 and (CH3)3SiNHTeF5 as the starting materials numerous new tellurium-nitrogen compounds have been synthesized. Almost all of them contain the >N-TeF5 group, which stabilizes many double-bonded systems such as O=C=NTeF5 and Cl4W=NTeF5. Cl2Se=NTeF5 is a rare example of a compound containing a discrete selenium-nitrogen double bond.
Intermolecular van der Waals radii of the nonmetallic elements have been assembled into a list of "recommended" values for volume calculations. These values have been arrived at by selecting from the most reliable X-ray diffraction data those which could be reconciled with crystal density at 0°K. (to give reasonable packing density), gas kinetic collision cross section, critical density, and liquid state properties. A qualitative understanding of the nature of van der Waals radii is provided by correlation with the de Broglie wave length of the outermost valence electron. Tentative values for the van der Waals radii of metallic elements - in metal organic compounds - are proposed. The paper concludes with a list of increments for the volume of molecules impenetrable to thermal collision, the so-called van der Waals volume, and of the corresponding increments in area per molecule.
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Part 12. This work was supported by the Deutscbe Forschungsgemeinschaft. the Fonds der Chemischen Industrie. and the State of Hesse. Part
11: H. Bock, CIT Fach;. Lub. 35 (1991) 557.