Selenide Complexes Research Articles

A Series of Low‐Coordinate Iron Selenido Complexes: Reactivity of a Linear Iron(I) Silylamide towards Selenium

AbstractA variety of different low‐coordinate iron selenide complexes is reported. These are obtained by reaction of the linear iron(I) silylamide K{18c6}[Fe(N(Dipp)SiMe3)2] (Dipp=2,6‐diisopropylphenyl) with red selenium. Careful adjustment of the reaction conditions results in the formation of unique low‐coordinate selenido iron complexes, namely a monoselenide bridged [2Fe−1Se]2+ complex, as well as mononuclear iron per‐ and triselenides. Further, C−H bond activation of one of the silylamide ligands by a putative terminal iron monoselenide is observed.

Engineering of MoSe2 decorated Ni/Co selenide complex hollow arrayed structures with dense heterointerfaces for high-performance aqueous alkaline Zn batteries

The development of advanced Ni/Co-based cathode electrodes for aqueous alkaline Zn batteries (AZBs) is highly desirable, but still remains a challenging task. Herein, we rationally design and synthesize the unique MoSe2 decorated Ni/Co selenide complex hollow arrayed structures (CH-MNCS) with dense heterointerfaces supported on nickel foam (NF) through a metal–organic framework-engaged strategy, in which heterostructured CoSe/MoSe2 hollow nanocages are uniformly assembled on heterostructured NiSex/MoSe2 nanotubes. Benefiting from the apparent morphological, structural and compositional advantages, aqueous AZBs based on the NF/CH-MNCS binder-free cathode exhibit high areal capacity and energy density of 1.42 mAh cm−2 and 2.45 mWh cm−2 at a current density of 2 mA cm−2, respectively, as well as decent rate capability and long cycling stability. Furthermore, density functional theoretical calculations further confirm the presence of heterointerfaces can not only enhance the electrical conductivity but also facilitate the adsorption of OH− ions in the electrolyte. More importantly, the quasi-solid-state NF/CH-MNCS//Zn batteries are also assembled to demonstrate the potential for practical applications. This work may provide a new perspective to construct heterostructured transition metal selenide complex hollow structures on conductive substrate for aqueous AZBs and other energy storage devices.

Coalescence of colloidal cadmium chalcogenide nanocrystals by controlled stripping of the surface ligands

Exploiting colloidal semiconductor nanocrystals (NCs) as building blocks for higher-order nanostructures can expand the field of nanoscience. For this reason, understanding the controlled coalescence of colloidal semiconductor NCs passivated with surface ligands is a big challenge for nanoscience research. Herein, we report a facile approach for activating the surface of CdSe NCs by stripping the carboxylate ligands with an alkylammonium–selenide complex for coalescence. The surface of as-prepared CdSe NC turned sparsely passivated and stoichiometric by the addition of alkylammonium–selenide complex; subsequently, coalescence readily occurred. Controlled coalescence or heterostructures can be realized through sophisticated control of the surface state of NCs. We anticipate that the surface-activated colloidal semiconductor NCs will act as promising nanoscale building blocks for fabricating functional nanostructures. Using a method described in this work, it is possible to not only understand the formation mechanism of coalescence, but to also construct higher-order supernanostructures.

Novel chalcogenide vanadium complexes with β-diimine ligand: synthesis and structural studies

Three new chalcogenide vanadium complexes with a β-diketiminate ligand have been synthesized by reduction of the elemental chalcogens (S, Se, Te) with [(µ-η6:η6-toluene){V(nacnac)}2] (1) (nacnac = HC(C(Me)NC6H3-iPr2)2). The structures of the sulfide and selenide complexes [((nacnac)V = E)2(μ,ƞ2-E2)] (E = S (2), Se (3)) are similar; the chalcogenides act both as bridging (E22-) and terminal (E2-) ligands. In compound [V2(µ-Te)2(nacnac)2] (4), all tellurium atoms are present only as bridging Te2- ligands. The compounds have been characterized by IR-spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The possibility of the formation of additional V = Te bonds in 4 has been studied using Hirshfeld analysis. It has been found that the difference in the reactivity of 1 towards Te is not due to the steric hindrance.

Synthesis, characterization, and structural properties of mercury(II), cadmium(II) and zinc(II) tripiperidinophosphine chalcogenide complexes

Reaction of metal chlorides (MCl2) with tripiperidinophosphine chalcogenides (Pip3PE) produces new dimer species (1–6) of the formula [MCl2(Pip3PE)]2 (Pip = piperidinyl; E = S or Se; M = Hg, Cd or Zn). These coordination complexes were characterized by elemental analysis, IR, multinuclear (31P, 113Cd and 199Hg) NMR spectroscopy and single crystal X-ray analysis. Compounds 1–6 exist as centrosymmetric homobimetallic dimers, [M(µ-Cl)Cl(Pip3PE)]2. Each dimer incorporates two µ2-chloro atoms and two terminal MCl bonds. The E atom of Pip3PE forms terminal ME bonds {S; 2.305(11); Se: 2.412(6)−2.589(15) Å} and thus the geometry about each metal centre is distorted tetrahedral and the range of tetrahedral bond angles is 102.83(3)° to 113.32(3)°. The PSe bond lengths of 2.183(9)–2.205(2) Å in the selenide complexes are slightly elongated compared to those in the free ligands [2.1090(4) Å]. The results are discussed and compared with those obtained for related analogues.

Construction of hierarchical nickel cobalt selenide complex hollow spheres for pseudocapacitors with enhanced performance

Construction bimetallic transition metal selenides with complex hollow structures is of significant importance but also extremely challenging. In this work, starting form metal-organic frameworks (MOFs), we have successfully synthesized the unique hierarchical (Ni0.33Co0.67)Se2 complex hollow spheres (CHSs), which manifest high specific capacitance as well as excellent rate performance and cycling stability, making them promising electrode materials for pseudocapacitors. The hierarchical (Ni0.33Co0.67)Se2 CHSs display a high specific capacitance of 827.9 F g−1 at the current density of 1 A g−1 and can still retain 646.2 F g−1 at a very high current density of 30 A g−1. Besides, a high capacitance of 865.8 F g−1 is obtained after cycling at 6 A g−1 for 2000 cycles, indicating good cycling stability. The excellent electrochemical performance could be owing to their high electrical conductivity and hierarchical complex hollow structure. Furthermore, an asymmetric supercapacitor (ASC) device employing (Ni0.33Co0.67)Se2 CHSs as positive electrode and activated carbon (AC) as negative electrode is also fabricated, which displays a high energy density of 29.1 Wh kg−1 at a power density of 800 W kg−1. These electrochemical results indicate the hierarchical (Ni0.33Co0.67)Se2 CHSs could be promising electrode materials for pseudocapacitors. The present work might also contribute to the rational construction of metal selenides with complex hollow structures for high-performance energy storage.

Monomeric and Oligomeric Metal Selenide Complexes from Structural Transformation of the Tetraselenotungstate Anion

Treatment of W(CO)6 with Na2Sex (x = 2–4) at 90 °C, prepared from heating selenium powder and sodium in DMF solution, afforded (Et4N)2[WSe4] (1) in a relatively high yield. Interaction of 1 with one equiv. [Me3NCH2Ph]Br in MeCN gave a cation exchanging product (Et4N)(Me3Ph2CH2N)[WSe4] (2) in a quantitative yield. Reaction of 1 with excess grey selenium in DMF produced monomeric polyselenide complex (Et4N)2[WO(Se4)2] (3). Treatment of 1 with equal equiv. anhydrous FeCl2 and excess PPh3 in DMF gave a dimeric complex (Fe(DMF)6)[W2Se4(μ-Se)2] (4). Similar reaction using MnCl2·4H2O salt easily gave rise to isolation of a trimeric complex (Mn(DMF)6)[WO(DMF)(μ-WSe4)2] (5). Reaction of 1 with anhydrous ZnCl2 in a mixed DMF/MeCN at 40 °C afforded a mixed-metal selenide complex (Et4N)2[Zn(μ-WSe4)2] (6). All complexes are well characterized by electronic, infrared, mass and NMR spectroscopies in this paper, and the solid-state structures of complexes 1–6 have been also established by X-ray crystallography. Interactions of tetraselenotungstate anion [WSe4]2− and first-row transition metal ions (Fe2+, Mn2+ and Zn2+) in the heating dimethylformide resulted in isolation of monomeric and oligomeric metal selenide complexes (Fe(DMF)6)[W2Se4(μ-Se)2] (Mn(DMF)6)[WO(DMF)(μ-WSe4)2] and (Et4N)2[Zn(μ-WSe4)2].

Assessing the dispersive and electrostatic components of the selenium-aromatic interaction energy by DFT.

Selenium has been increasingly recognized as an important element in biological systems, which participates in numerous biochemical processes in organisms, notably in enzyme reactions. Selenium can substitute sulfur of cysteine and methionine to form their selenium analogues, selenocysteine (Sec) and selenomethionine (SeM). The nature of amino acid pockets in proteins is dependent on their composition and thus different non-covalent forces determine the interactions between selenium of Sec or SeM and other functional groups, resulting in specific biophysical behavior. The discrimination of selenium toward sulfur has been reported. In order to elucidate the difference between the nature of S-π and Se-π interactions, we performed extensive DFT calculations of dispersive and electrostatic contributions of Se-π interactions in substituted benzenes/hydrogen selenide (H2Se) complexes. The results are compared with our earlier reported S-π calculations, as well as with available experimental data. Our results show a larger contribution of dispersive interactions in Se-π systems than in S-π ones, which mainly originate from the attraction between Se and substituent groups. We found that selenium exhibits a strong interaction with aromatic systems and may thus play a significant role in stabilizing protein folds and protein-inhibitor complexes. Our findings can also provide molecular insights for understanding enzymatic specificity discrimination between single selenium versus a sulfur atom, notwithstanding their very similar chemical properties.

Taming Silicon Congeners of CO and CO2 : Synthesis of Monomeric SiII and SiIV Chalcogenide Complexes.

The synthesis of the unprecedented monomeric SiII selenide complex (bis-NHC)Si=Se→GaCl3 2 (bis-NHC=bis-N heterocyclic carbene, H2 C[{NC(H)=C(H)N(Dipp)}C:]2 , Dipp=2,6-iPr2 C6 H3 ), bearing the elusive SiSe ligand as a heavy CO homologue by the reaction of the silylone-GaCl3 adduct (bis-NHC)Si→GaCl3 1 with elemental selenium in acetonitrile, is reported. The similar conversion of 1 with excess selenium conducted in THF afforded the SiSe2 complex (bis-NHC)Si(=Se)Se→GaCl3 3. Remarkably, the reaction of 1 with Te=P(nBu)3 as a gentle Te transfer reagent led to the isolation of the monomeric SiTe2 complex (bis-NHC)SiTe2 4, the first structurally characterized Lewis acid free heavy CO2 homologue complex. The isolated compounds 2, 3, and 4 have been fully characterized, including single-crystal X-ray diffraction analyses. Their electronic structures and spectroscopic data have also been studied by quantum-chemical calculations.

Taming Silicon Congeners of CO and CO2: Synthesis of Monomeric SiII and SiIV Chalcogenide Complexes

AbstractThe synthesis of the unprecedented monomeric SiII selenide complex (bis‐NHC)Si=Se→GaCl3 2 (bis‐NHC=bis‐N heterocyclic carbene, H2C[{NC(H)=C(H)N(Dipp)}C:]2, Dipp=2,6‐iPr2C6H3), bearing the elusive SiSe ligand as a heavy CO homologue by the reaction of the silylone–GaCl3 adduct (bis‐NHC)Si→GaCl3 1 with elemental selenium in acetonitrile, is reported. The similar conversion of 1 with excess selenium conducted in THF afforded the SiSe2 complex (bis‐NHC)Si(=Se)Se→GaCl3 3. Remarkably, the reaction of 1 with Te=P(nBu)3 as a gentle Te transfer reagent led to the isolation of the monomeric SiTe2 complex (bis‐NHC)SiTe2 4, the first structurally characterized Lewis acid free heavy CO2 homologue complex. The isolated compounds 2, 3, and 4 have been fully characterized, including single‐crystal X‐ray diffraction analyses. Their electronic structures and spectroscopic data have also been studied by quantum‐chemical calculations.

Ferrocenyl-functionalized Sn/Se and Sn/Te complexes: synthesis, reactivity, optical, and electronic properties.

An adamantane-shaped, ferrocenyl-substituted tin selenide complex, [(FcSn)4Se6] (1; Fc = ferrocenyl), and a ferrocenyl-substituted tin telluride five-membered ring, [(Fc2Sn)3Te2] (2), were obtained upon treatment of FcSnCl3 with K2E (E = Se, Te). Complex 1 further reacts with Na2S·9H2O and [Cu(PPh3)3Cl] to form a ternary complex, [(CuPPh3)6(S/Se)6(SnFc)2] (3). We discuss structures, optical and electrochemical properties as well as Mössbauer spectra.

Chlorination of Phosphane Selenides

AbstractChlorination of the phosphane selenide iPrtBu2PSe with PhICl2 leads to the compound iPrtBu2PSe2Cl2, which contains a P–Se–SeCl2 moiety and is formally a phosphane selenide complex of selenium dichloride. Two polymorphs of the product were identified by X‐ray structure analysis. The analogous reaction with tBu3PSe gave an oil, presumably tBu3PSe2Cl2, from which small quantities of tBu3PSe3Cl2 were obtained and characterized by X‐ray structure analysis.

Reductive selenidation of [Cp*MoO2Cl]: Synthesis, structure and bonding in new binuclear and trinuclear clusters

The reaction between in situ generated H2Se and [Cp*MoO2Cl] (1) produces a mixture of binuclear and trinuclear selenium clusters. New selenide complex [Cp*2Mo2Se6] (2) was isolated from CH2Cl2 extracts of the products mixture and characterized by X-ray analysis. This binuclear cluster contains two unprecedented Se34− ligands isoelectronic to I3−. Column chromatography of extracts in air produced two bands, from which [Cp*2Mo2O2Se2] (3) and a new triangular cluster [Cp*3Mo3Se4][ZnCl3(H2O)] (4) were isolated and structurally characterized. The products were characterized by 1H and 77Se NMR, ESI–MS, IR and elemental analysis. Quantum-chemical calculations were used to analyze the Mo–Mo bonding and to help identify lines in 77Se NMR spectra. Crystal and molecular structure of starting [Cp*MoO2Cl] was also determined.

Dimethyl selenide complexes with compounds of Group IIIA elements: electron density redistribution and interaction energy partitioning

Molecular structures of dimethyl selenide complexes with AX3 (A = B, Al, Ga, In; X = H, Me) compounds of Group IIIA elements were calculated by the PBE1PBE/Sapporo-TZ method. A complex approach to study the nature of interactions is proposed, which involves analysis of electron localization/delocalization characteristics and their influence on charge transfer and energy effects of complexation. It is shown that electron sharing is more important for stabilization of the complexes under study than electrostatic interaction between their fragments. It is demonstrated that analysis of local (topological) characteristics of the electron density distribution is insufficient to discover similarity/dissimilarity in the nature of some complexes. The energies of interaction in the complexes under study are mainly composed of the contributions of Se atom as active center of the donor molecule and the entire acceptor molecule. Energy characteristics of local interaction between Se atom and Group IIIA element atom are not representative.

Cycloaurated triphenylphosphine-sulfide and -selenide

The first examples of cycloaurated phosphine sulfides and triphenylphosphine selenide have been synthesised; these complexes are fairly rare examples of gold(iii) complexes with potentially reducing sulfur- and selenium-donor ligands. The cycloaurated complex (AuCl(2)(2-C(6)H(4)P(S)Ph(2)) was synthesised in good yield by transmetallation of the organomercury precursor Hg(2-C(6)H(4)P(S)Ph(2))(2) with Me(4)N[AuCl(4)]. A route to the chloro-mercury analogue ClHg(2-C(6)H(4)P(S)Ph(2)) was developed by reaction of the cyclomanganated triphenylphosphine sulfide (CO)(4)Mn(2-C(6)H(4)P(S)Ph(2)) with HgCl(2); this mercury substrate was also used in the synthesis of AuCl(2)(2-C(6)H(4)P(S)Ph(2)). The cycloaurated triphenylphosphine selenide complex AuCl(2)(2-C(6)H(4)P(Se)Ph(2)) was synthesised by an analogous methodology using the new phosphine selenide Hg(2-C(6)H(4)P(Se)Ph(2))(2) [prepared from Hg(2-C(6)H(4)PPh(2))(2) and elemental Se under sonication]. The phosphonamidic analogue AuCl(2)(2-C(6)H(4)P(S)(NEt(2))(2)) has also been synthesised from PhP(S)(NEt(2))(2)via lithiation and mercuration. X-Ray crystal structures of several compounds are reported, and show the presence of puckered ring systems.

Thallium(III) complexes of the metalloligands [Pt 2(μ-S) 2(PPh 3) 4] and [Pt 2(μ-Se) 2(PPh 3) 4

Reactions of [Pt 2(μ-S) 2(PPh 3) 4] with the diarylthallium(III) bromides Ar 2TlBr [Ar = Ph and p-ClC 6H 4] in methanol gave good yields of the thallium(III) adducts [Pt 2(μ-S) 2(PPh 3) 4TlAr 2] +, isolated as their BPh 4 - salts. The corresponding selenide complex [Pt 2(μ-Se) 2(PPh 3) 4TlPh 2]BPh 4 was similarly synthesised from [Pt 2(μ-Se) 2(PPh 3) 4], Ph 2TlBr and NaBPh 4. The reaction of [Pt 2(μ-S) 2(PPh 3) 4] with PhTlBr 2 gave [Pt 2(μ-S) 2(PPh 3) 4TlBrPh] +, while reaction with TlBr 3 gave the dibromothallium(III) adduct [Pt 2(μ-S) 2(PPh 3) 4TlBr 2] +[TlBr 4] −. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt 2(μ-S) 2(PPh 3) 4TlPh 2]BPh 4, [Pt 2(μ-S) 2(PPh 3) 4TlBrPh]BPh 4 and [Pt 2(μ-S) 2(PPh 3) 4TlBr 2][TlBr 4] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl–S and Pt⋯Tl distances, and an increasing S–Tl–S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported.

Dimethyl selenide complexes of copper, gallium and indium halides as potential precursors for selenium-containing chalcopyrite semiconducting materials

The coordination chemistry of copper, gallium and indium halides with the simplest possible selenoether i.e. Me 2Se was investigated with the aim to use the resulting complexes as precursors for selenium-containing chalcopyrite semiconducting materials. An optimized general procedure for the high yield synthesis is described and the influence of a halide ion on the structure and solubility of these metal halide dimethyl selenide complexes are discussed. These complexes were characterized by the elemental analysis, FT-IR and 1H NMR spectroscopy as well as single crystal X-ray structures, the later study showing them to be monomeric for gallium halides, mono- or dimeric for indium halides and either an ion-pairs or 2-D extended structure in the case of copper halides.

Crystal growth of nanoscaled europium selenide having characteristic crystal shapes

Tetrapod-shaped EuSe nanocrystals were prepared through the thermal reduction of europium chloride an organic selenide complex, n-hexadecylamine, and two additives oleic acid and oleylamine. The obtained EuSe nanoparticles were characterized by X-ray diffraction (XRD). The crystal grain size from the XRD spectrum was estimated to be 50 nm. In contrast, observation of the transmission electron microscope (TEM) gave larger sized EuSe (average size: 200 nm). Anisotropic crystal-growth of EuSe nanocrystals was achieved by addition of a small amount of oleic acid in the crystal growth process.

A case-control study on the relationship of hearing function and blood concentrations of lead, manganese, arsenic, and selenium

Previous research has suggested that heavy metals may be ototoxic in humans, and further, that a reversal of this toxicity may occur when the trace element selenium is present, through formation of metals selenide complexes. This study investigates the relationship between hearing thresholds and blood concentrations of four elements (selenium, lead, manganese, and arsenic) in factory workers, Taiwan. We conducted a hospital-based case-control study with 294 individuals who received the periodic occupational health examination in the Kaohsiung Medical University Hospital. All control subjects (n=173) had normal hearing. Case subjects (n=121) had average hearing threshold over 25 decibels (dB). In all individuals, blood concentrations of lead (Pb), manganese (Mn), arsenic (As), and selenium (Se) were determined by an ICP-MS and standard methods. Possible confounding factors were collected by a questionnaire and medical history reviews. Relationships were analyzed by multiple linear regressions and mixed model. Geometric means of Pb, Mn, As, and Se were determined for case subjects (107.2, 5.5, 17.8, and 229.1 microg/L) and controls (38.9, 5.4, 15.5, and 234.4 microg/L). In our regression models, age, lead and selenium concentrations (logarithmic transformed) were associated significantly with hearing thresholds. In addition, we found that the selenium was inversely associated with hearing thresholds, and may be an antagonist to lead ototoxicty. The present study demonstrated a dose-response relationship between blood lead and hearing thresholds, after adjusting other potential confounders in multiple regressions. In addition, we found that selenium may be a protection element on auditory function. However, additional studies will be needed to clarify the mechanisms of lead toxicity and selenium on the hearing function in molecular and genetic levels.

Assessment of some elements in human permanent healthy teeth, their dependence on number of metallic amalgam fillings, and interelements relationships

In this study, 60 human permanent healthy teeth (without filling) were collected postmortem and analyzed using flame atomic absorption spectrometry (FAAS), cold vapor atomic absorption spectrometry (CVAAS), hydride generation atomic absorption spectrometry (HGAAS), and electrothermal atomic absorption spectrometry (ETAAS) for the determination of Ca, Hg, Se, Cu, and Ag. The concentration of these elements was assessed in carious and noncarious teeth, different tooth groups, with age and with number of amalgam fillings. A negative correlation was found between Ca and the number of amalgam fillings, and significant negative correlations were found between Ca and three other metals (Hg, Ag, and Cu) that indicate the possibility of substitutions of Ca by three other metals. Significant positive correlations were found among the number of amalgam fillings and Hg, Ag, Cu and Se showed metal concentration in permanent healthy teeth were affected by the presence of the number of amalgam filling. In addition, significant positive correlations between Hg and Ag, Hg and Cu, and Ag and Cu proved the suspicion that the Hg content in permanent healthy teeth was mainly found because of the influence of amalgam filling, not from other sources. Moreover, the significant positive correlation between Hg-Se and Ag-Se showed the formation of mercuric selenide and silver selenide complexes as part of a natural mechanism of detoxification. Consequently, the permanent healthy teeth would be considered as a bioindicator for the accumulation of long-term exposure of Hg and Ag.