Title Anions Research Articles

Homoleptic trimethylsilylchalcogenolato zincates [Zn(ESiMe3)3]- and stannanides [Sn(ESiMe3)3]- (E = S, Se): precursors in solution-based low-temperature binary metal chalcogenide and Cu2ZnSnS4 (CZTS) synthesis.

Organic cation salts with homoleptic zincate and stannanide anions, Ph4P [Zn(ESiMe3)3] (E = S (1a), Se (1b)) and Cat [Sn(ESiMe3)3] (Cat = Ph4P+ (E = S (2a-Ph4P); Cat = PPN+ (E = S 2a-Ph4P, Se (2a)) are presented and structurally characterized. Efforts to isolate neutral thermally metastable stannane precursors [Sn(ESiMe3)4] (E = S (3), Se(4)) are reported as well. The thermal decomposition of the presented precursors to yield binary sulfides and selenides of zinc and tin is investigated. Furthermore, the potential of using the title anions as precursors in solution-based low-temperature synthesis of Cu2ZnSnS4 (CZTS) by coprecipitation with [Cu(tmtu)3]PF6 and subsequent annealing is discussed.

Synthesis of the Unsaturated [MMoCp(µ‐PR2)(CO)5]– Anions (M = Mn, R = Ph; M = Re, R = Cy): Versatile Precursors of Heterometallic Complexes

An efficient synthetic route for the preparation of the title anions was implemented, and it involved two‐electron reduction of iodide‐bridged [MMoCp(µ‐I)(µ‐PR2)(CO)5] (Cp = cyclopentadienyl) complexes by using Na(Hg). Reaction of these anions with (NH4)PF6 (in THF) and ClSnPh3 (in MeCN) gave [MMoCp(µ‐H)(µ‐PR2)(CO)5(NH3)] and [MoReCp(µ‐PCy2)(SnPh3)(CO)5(NCMe)] (Cy = cyclohexyl), respectively, with incorporation of the corresponding electrophile at either a bridging (H+) or terminal (SnPh3) position and the addition of an external ligand (NH3 and NCMe, respectively) to render electron‐precise derivatives (dMo–Re > 3.1 Å). In contrast, reaction with [AuCl{P(pTol)3}] yielded stable unsaturated trimetallic [AuMMoCp(µ‐PR2)(CO)5{P(pTol)3}] clusters (dMo–Mn = 2.71 Å).

ChemInform Abstract: Theoretical and Synthetic Study on the Existence, Structures, and Bonding of the Halide‐Bridged [B2X7]‐ (X: = F, Cl, Br, I) Anions.

AbstractThe structures of the title anions are calculated at the MP2 level of theory.

Nucleophilic behaviour of dioxo- and thiooxophosphorane complexes [MoCp(CO)2{E,P-EP(O)(2,4,6-C6H2(t)Bu3)}](-) (E = O, S).

The title anions were prepared as (DBU-H)(+) salts upon reaction of the oxophosphinidene complex (H-DBU)[MoCp(CO)2{P(O)R*}] with either dimethyldioxirane or elemental sulphur (R* = 2,4,6-C6H2(t)Bu3; Cp = η(5)-C5H5, DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene). The dioxophosphorane complex failed to react with MeI at room temperature, but reacted readily with (Me3O)BF4 to give the phosphonite complex [MoCp{O,P-OP(OMe)R*}(CO)2]. In contrast, the thiooxophosphorane complex reacted with MeI to give the thiolophosphinide derivative [MoCp{S,P-(MeS)P(O)R*}(CO)2], whereas its reaction with (Me3O)BF4 gave a mixture of the latter complex and the phosphonothiolate isomer [MoCp{S,P-SP(OMe)R*}(CO)2] in similar amounts. Other electrophiles were added selectively to the terminal O atom of the R*POS ligand. Thus the thiooxophosphorane complex reacted with ClC(O)C2H3, [NH4]PF6, ClSiMe3, ClSnMe3 and [ZrCp2Cl2] to give the corresponding derivatives [MoCp{S,P-SP(OX)R*}(CO)2] (X = C(O)C2H3, H, SiMe3, SnMe3, ZrCp2Cl). The structure of two of these products (X = C(O)C2H3, SiMe3) was determined by single-crystal X-ray diffraction studies. Density functional theory (DFT) calculations of the title anions and some of their derivatives indicated that attachment of an external electrophile to the terminal O atom of the thiooxophosphorane ligand is favoured under the conditions of charge control, while the sulphur atom is the favoured site under the conditions of orbital control, although it leads to less stable products.

Theoretical investigation of the conventional CX1X2[rad]− (X1, X2 = H, F, Cl, Br, and I) compounds

The effects of substituents have been evaluated in detail via investigating on the electronic and molecular structures of the compounds constructed by model CX1X2− (X1, X2=H, F, Cl, Br, I) using the DFT-B3LYP, MP2 and QCISD(T) methods with the aug-cc-pVTZ/RECP basis set. Comparisons are performed for the geometries of each compound CX1X2−, as well as with the analogous silicon-anion SiX1X2−. Moreover, the spin density (Sd) and second-order perturbative (E(2)) analysis are discussed to assess stabilization of these radical anions CX1X2−, suggesting the heavier the substituent, the stronger the stability is. Besides, we also estimated the ionization energies (IE) and proton affinity (PA) of the title anions and explored the difference between them for the same compound molecule.

Photoelectron Imaging and Theoretical Studies of Silver Monohalides AgX– (X = Cl, Br, I) and AuCl–

Photodetachment of AgX(-) (X = Cl, Br, I) and AuCl(-) is studied by a photoelectron velocity map imaging technique and theoretical calculations. Photoelectron spectra (PES) and photoelectron angular distributions (PADs) were obtained. The vibrationally resolved spectra provided approximately equal electron affinities (EAs) for AgX: 1.593(22) eV for AgCl, 1.623(21) eV for AgBr, and 1.603(22) eV for AgI, respectively. Franck-Condon simulations of these spectra gave the equilibrium bond lengths and vibrational frequencies of the title anions. Relativistic density functional theory (DFT) calculations using BLYP, PW91, PBE, and BP86 functionals have been performed to predict the EAs of the AgX (X = Cl, Br, I) molecules. The computed EAs at the BP86 level of theory are in good agreement with the experimental values. Energy partitioning analyses (EPA) at the BP86(ZORA)/QZ4P level of theory of both anions and their neutrals were reported.

ChemInform Abstract: Preparation of 2‐Azaallyl Anions and Imines from N‐Chloroamines and Their Cycloaddition and Allylation.

AbstractTreatment of a variety of N‐chloroamines, derived from functionalized dialkylamines, with base in the presence of additives generates the title anions which undergo [4 + 2] cycloaddition with olefins.

HCB11(CF3)nF11-n−: Inert Anions with High Anodic Oxidation Potentials

Cs salts of four of the title anions were prepared by fluorination of salts of partly methylated (n = 11, 10) or partly methylated and partly iodinated (n = 6, 5) CB(11)H(12)(-) anions. The CH vertex is acidic, and in the unhindered anion with n = 6 it has been alkylated. Neat Cs(+)[1-H-CB(11)(CF(3))(11)](-) is as treacherously explosive as Cs(+)[CB(11)(CF(3))(12)](-), but no explosions occurred with the salts of the other three anions. BL3YP/6-31G* gas-phase electron detachment energies of the title anions are remarkably high, 5-8 eV. Treated with NiF(3)(+) in anhydrous liquid HF at -60 °C, anions with n = 11 or 10 resist oxidation, whereas anions with n = 6 or 5 are converted to colored EPR-active species, presumably the neutral radicals [HCB(11)(CF(3))(n)F(11-n)](•). These are stable for hours at -60 °C after extraction into cold perfluorohexane or perfluorotri-n-butylamine solutions. On warming to -20 °C in a Teflon or quartz tube, the color and EPR activity disappear, and the original anions are recovered nearly quantitatively, suggesting that the radicals oxidize the solvent.

Chemistry of the Oxophosphinidene Ligand. 2. Reactivity of the Anionic Complexes [MCp{P(O)R*}(CO)2]−(M = Mo, W; R* = 2,4,6-C6H2tBu3) Toward Electrophiles Based on Elements Different from Carbon.

The anionic oxophosphinidene complexes (H-DBU)[MCp{P(O)R*}(CO)(2)] (M = Mo, W; R* = 2,4,6-C(6)H(2)(t)Bu(3); Cp = η(5)-C(5)H(5), DBU = 1,8-diazabicyclo [5.4.0] undec-7-ene) displayed multisite reactivity when faced with different electrophilic reagents. The reactions with the group 14 organochloride compounds ER(4-x)Cl(x) (E = Si, Ge, Sn, Pb) led to either phosphide-like, oxophosphinidene-bridged derivatives [MCp{P(OE')R*}(CO)(2)] (E' = SiMe(3), SiPh(3), GePh(3), GeMe(2)Cl) or to terminal oxophosphinidene complexes [MCp{P(O)R*}(CO)(2)(E')] (E' = SnPh(3), SnPh(2)Cl, PbPh(3); Mo-Pb = 2.8845(4) Å for the MoPb compound). A particular situation was found in the reaction with SnMe(3)Cl, this giving a product existing in both tautomeric forms, with the phosphide-like complex [MCp{P(OSnMe(3))R*}(CO)(2)] prevailing at room temperature and the tautomer [MCp{P(O)R*}(CO)(2)(SnMe(3))] being the unique species present below 203 K in dichloromethane solution. The title anions also showed a multisite behavior when reacting with transition-metal based electrophiles. Thus, the reactions with the complexes [M'Cp(2)Cl(2)] (M' = Ti, Zr) gave phosphide-like derivatives [MCp{P(OM')R*}(CO)(2)] (M = Mo, M' = TiCp(2)Cl, ZrCp(2)Cl; M = W, M' = ZrCp(2)Cl), displaying a bridging κ(1),κ(1)-P,O- oxophosphinidene ligand connecting MCp(CO)(2) and M'Cp(2)Cl metal fragments (W-P = 2.233(1) Å, O-Zr = 2.016(4) Å for the WZr compound]. In contrast, the reactions with the complex [AuCl{P(p-tol)(3)}] gave the metal-metal bonded derivatives trans-[MCp{P(O)R*}(CO)(2){AuP(p-tol)(3)}] (M = Mo, W; Mo-Au = 2.7071(7) Å). From all the above results it was concluded that the terminal oxophosphinidene complexes are preferentially formed under conditions of orbital control, while charge-controlled reactions tend to give derivatives with the electrophilic fragment bound to the oxygen atom of the oxophosphinidene ligand (phosphide-like, oxophosphinidene-bridged derivatives).

Spin−Orbit Effects on the Aromaticity of the Re3X92− (X = Cl, Br) Cluster Ions

In our recent article (Chem. Phys. Lett. 2008, 467, 94-96), we reported the aromaticity via NICS calculations of the neutral Re(3)Cl(9) and Re(3)Br(9) clusters. Spin-orbit effects decrease their aromaticity due to the fact that the 5d(3/2) spinors are mostly occupied and are more contracted than the scalar 5d orbitals. Here, we report that the title anions are also aromatic but, oppositely, spin-orbit effects increase the clusters' aromaticity due to the fact that the 5d(5/2) spinors are now being populated and are more expanded than the scalar 5d orbital. All the clusters discussed here have larger induced diatropic ring currents than benzene.

Monocapped Trigonal‐Prismatic Transition‐Metal Heptaazides: Syntheses, Properties, and Structures of [Nb(N3)7]2− and [Ta(N3)7]2−

Structures with a bang: The title anions are the first examples of doubly charged heptaazido anions and structurally characterized transition-metal heptaazides. Contrary to the either monocapped octahedral or pentagonal-bipyramidal actinide trianion [U(N3)7]3−, but in accord with the [NbF7]2− anion, the title anions have monocapped trigonal-prismatic structures (see picture; M=Nb, Ta).

The Simultaneous Presence of Different Varieties of Intermolecular Hydrogen Bonds in a New Layer-Type Anionic Host Lattice Built of Thiourea, Fumaric Acid and Fumarate Anion

A new inclusion complex (n-C4H9)4N+C4H3O4− · C4H4O4 · (NH2)2CS has been prepared and characterized by X-ray crystallography. Crystal data: space group P\( \overline 1 \), a = 8.799(2) A, b = 9.590(1) A, c = 18.684(4) A, α = 89.63(1)°, β = 79.56(1)°, γ = 79.74(1)°, V = 1525.2(5) A3, Z = 2, R1 = 0.0562 and wR = 0.1033. In the title compound, thiourea molecules, fumaric acid and fumarate anions are joined together by typical O–H···O, N–H···O and N–H···S, plus weak C–H···O and C–H···S, hydrogen bonds to generate a hydrogen-bonded layer corresponding to the (100) family of planes. The tetra-n-butylammonium cations are orderly arranged in a sandwich-like packing mode between the stacked layers. The simultaneous presence of different varieties of intermolecular hydrogen bonds is an interesting feature of the title compound.

Theoretical studies on the geometry, vibrational frequencies and electronic properties of [X(OH) 6Mo 6O 18] 4−/3− (X = Fe II/Co III) Anderson-type anions

The geometry parameters of [Fe II(OH) 6Mo 6O 18] 4− and [Co III(OH) 6Mo 6O 18] 3− as protonated form of Anderson-type anions have been investigated at the level of density functional theory, using B3LYP and ab initio Hartree–Fock (HF) methods. The effect of basis sets has been investigated using four basis sets. Based on optimized structures, vibrational frequencies calculations have been done. The agreement between reported experimental data and theoretical values is, in general, good. Also electronic properties of protonated form have been investigated for [Al III(OH) 6Mo 6O 18] 3− with the other title anions which suggested the [(X(OH) 6) n− @M 6O 18] general formula to describe the anionic subunit X(OH) 6 surrounded by M 6O 18 neutral ring.

Air-Initiated Radical Polymerization of Lithium Salts of ω-(Undecamethylcarba-closo-dodecaboran-1‘-yl)alk-1-enes, CH2CH(CH2)n-2C(BMe)11- Li+

We report an easy access to the salts of the LiC(BMe)11- anion, which greatly simplifies the synthesis of compounds carrying the -C(BMe)11- substituent, including the title anions. The previously recognized and puzzling spontaneous oligomerization of the solid lithium salts CH2=CH(CH2)(n-2)C(BMe)11- Li+ upon storage under ambient conditions is now shown to proceed by a radical mechanism, with the "naked" Li+ cation acting as a catalyst. The degree of polymerization is higher in solution, especially when azoisobutyronitrile (AIBN) is used as initiator (up to approximately 50). Initiation by the thermal decomposition of AIBN is also catalyzed by naked Li+, and this initiator is effective at room temperature. Di-tert-butyl peroxide and UV irradiation can also be used. The observation of Li+ catalysis agrees with a prior prediction from ab initio calculations, according to which Li+ complexation of ethylene strongly lowers the activation energy for methyl radical addition. The results bear on the current discussion of the possible sensitivity of radical clocks to their molecular environment and suggest that naked Li+ will catalyze the radical polymerization of simple terminal alkenes.

Secondary N-nitrosocarbamate anions: Structure and alkylation reactions. A DFT study

The current article reports theoretical studies (DFT: B3LYP/6-31+G(d)) on the structure and alkylation reactions of the anions of some secondary N-nitrosocarbamates, a class of ambident nucleophiles whose chemistry has been little explored. Several anions ( 1– 4), with an increasing size of the carbamate alkyl (aryl) group were investigated, in an attempt to establish the influence of the size of that group on the thermal stability and regioselectivity of alkylation of the title anions. The conclusion is that thermal stability and the mode of reaction are affected significantly only in the presence of very large and branched carbamate groups. The thermal decomposition studies at the B3LYP/6-31+G(d) level of theory yield quantitative results that are in very good or excellent agreement with experimental data. A detailed study of N- vs. O-alkylation reactions was conducted, in an attempt to reveal the nature and origin of regioselectivity. Several factors seem to play prominent role: (1) charge distribution within the N-nitrosocarbamate anion; (2) exothermicity of alkylation; (3) size of electrophile and (4) size of the carbamate alkyl (aryl) group. Computational results on the alkylation reactions of N-nitrosocarbamate anions are compared to results for alkylation of the acetone enolate ion, the outcome for the latter being in sharp contrast to earlier, lower-level calculations. In addition, alkylation studies were conducted on the Z-isomers of the title anions and the results indicate that they undergo O-alkylation with significantly lower barriers compared to the E-isomers. However, Z-isomers are 5–6 kcal/mol less stable thermodynamically and application of the Curtin–Hammett principle leads to the conclusion that O-alkylation occurs almost exclusively on the E-isomers.

Derivatization of deltahedral Zintl ions by nucleophilic addition: [Ph-Ge9-SbPh2]2- and [Ph2Sb-Ge9-Ge9-SbPh2]4-.

The type of the reactions of addition of exo-bonded groups to deltahedral Zintl ions such as Ge9(n-) has been established as addition of anionic nucleophiles. Various nucleophiles such as Ph2Bi-, Ph2Sb-, Ph- interact with the relatively low-lying LUMO of Ge9(2-) and/or the half filled HOMO of Ge9(3-) and bond to the clusters. The title anions, characterized in their (K-crypt) salts where crypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo-[8.8.8]-hexacosane, and the previously characterized [Ph2Sb-Ge9-SbPh2](2-) are made by a reaction of K4Ge9 with SbPh3 in ethylenediamine. [Ph-Ge9-SbPh2](2-) is the first ogranically functionalized deltahedral Zintl ion, i.e., a deltahedral ion with a direct carbon-cluster covalent bond, that can exists without the substituents as well. The Ge(9) clusters resemble tricapped trigonal prisms with one elongated edge (one of the three edges parallel to the pseudo 3-fold axis). The two substituents are always bonded to the vertexes of such an elongated edge. The same is true for the intercluster bond in [Ph2Sb-Ge9-Ge9-SbPh2)](4-).

Synthesis and characterization of copper-, zinc-, manganese-, and cobalt-substituted dimeric heteropolyanions, [(alpha-XW9O33)2M3(H2O)3](n-) (n = 12, X =As(III), Sb(III), M = Cu(2+), Zn(2+); n = 10, X = Se(IV), Te(IV), M = Cu(2+) and [(alpha-AsW9O33)2WO(H2O)M2(H2O)2](10-) (M = Zn(2+), Mn(2+), Co(2+).

Interaction of the lacunary [alpha-XW9O33](9-) (X = As(III), Sb(III)) with Cu(2+) and Zn(2+) ions in neutral, aqueous medium leads to the formation of dimeric polyoxoanions, [(alpha-XW9O33)2M3(H2O)3](12-) (M = Cu(2+), Zn(2+); X = As(III), Sb(III)), in high yield. The selenium and tellurium analogues of the copper-containing heteropolyanions are also reported: [(alpha-XW9O33)2Cu3(H2O)3](10-) (X = Se(IV), Te(IV)). The polyanions consist of two [alpha-XW9O33] units joined by three equivalent Cu(2+) (X = As, Sb, Se, Te) or Zn(2+) (X = As, Sb) ions. All copper and zinc ions have one terminal water molecule resulting in square-pyramidal coordination geometry. Therefore, the title anions have idealized D3h symmetry. The space between the three transition metal ions is occupied by three sodium ions (M = Cu(2+), Zn(2+); X = As(III), Sb(III)) or potassium ions (M = Cu(2+); X = Se(IV), Te(IV)) leading to a central belt of six metal atoms alternating in position. Reaction of [alpha-AsW9O33](9-) with Zn(2+), Co(2+), and Mn(2+) ions in acidic medium (pH = 4-5) results in the same structural type but with a lower degree of transition-metal substitution, [(alpha-AsW9O33)2WO(H2O)M2(H2O)2](10-) (M = Zn(2+), Co(2+), Mn(2+)). All nine compounds are characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analysis. The solution properties of [(alpha-XW9O33)2Zn3(H2O)3](12-) (X = As(III), Sb(III)) were also studied by 183W-NMR spectroscopy.

Arylthiazylamides: syntheses, structures, and bonding properties.

Air-sensitive, thermally unstable tris(dimethylamino)sulfonium (TAS) salts (3) of the title anions [ArNSN]- have been prepared from corresponding sulfurdiimides Ar-N=S=N-SiMe3 (2) by Si-N bond cleavage with [(Me2N)3S]-[Me3SiF2]- (TASF). They are characterized by low-temperature X-ray crystallography as Z isomers. Because of the very short terminal S-N distance (144.2 (3h)-147.9 (3i)pm) and the relatively long internal S-N distance (158.3 (3i)-160.3 (3c) pm) the [ArNSN]- ions should be regarded as thiazylamides 1b, rare species containing a S triple bond N triple bond. A bonding model is developed and the experimental results are compared with those of restricted Hartree-Fock (RHF), density functional theory (DFT), and Møller-Plesset second-order (MP2) calculations.

Synthesis and 183W and 51V Nmr Characterization of α- and β-K6H[Gew9V3O40].Xh2O and Esr Spectra of Mixed-Valence Vanadium Polyanions

Trivanadium-substituted heteropolytungstates, α- and β-K6H-[GeW9V3Q40]* xH2O (α- and β-GeW9V3), have been synthesized from their lacunary precursors, α- and β- [GeW9O34]10, and characterized by elemental analysis, cyclic voltammograms and 51V and 183NMR spectra. 183w NMR spectra of the title anions consist of tulo lines (intensity ratio 2 : 1) as expected for the C3V structure of trisubstituted α- and β-Keggin anions. The 2Jw.o.w couplings of the title anions exhibit sharper lines (19.35 and 16.73 Hz. respectively), confirming that the title complexes contain substituted vanadium in adjacent comer-shared octahedra of α- and β-Keggin structures, respectively. The solution ESR spectra of the one-electron-reduced anions consist of more than 40 equally spaced lines, showing that the three VO6 octahedra in both α- and β-fom are comer-shared and one of the bridging oxygen atams is protonated at pH 4.7.

Observation, in mass spectra and charge-inversion spectra, of the anions of some diatomic species containing B, Si or P atoms

The title anions are mostly unknown experimentally, but many are predicted to have stable states. A search was therefore made, and the following fifteen anions were found in the accurate-mass spectra of the given precursors: BH - B - 2 from reduced BBr 3 BC - from B(OCH 3) 3; BN - and BS - from BBr 3 (or BH 3) complexed with NH 3 and S 2CI 2 respectively; SiC - and SiO - from CH 3Si(OCH 3) 3; SiN - from (CH 3) 3SiN 3; SiX -(X = F, or Cl) from SiX 4; PC - from CL 2PCH 3; PN - and PCl - from P 3N 3Cl 6; PF - from HPF 6 (aq.) and PS - from P 4S 10. These anions were also observed to be formed in charge-inversion reactions of the cations. The anions BF -, BCl - and BP - were searched for but not found. Charge inversion spectra; Double charge transfer; Diatomic anions.