Diimido‐, Imido(oxo)‐, Dioxo‐ und Imido(alkyliden)‐Halbsandwich‐Verbindungen über selektive Hydrolyse und α—H‐Abstraktion an Organylkomplexen des sechswertigen Molybdäns und Wolframs

Diimido, Imido Oxo, Dioxo, and Imido Alkylidene Halfsandwich Compounds via Selective Hydrolysis and α—H Abstraction in Molybdenum(VI) and Tungsten(VI) Organyl Complexes Organometal imides [(η⁵‐C₅R₅)M(NR′)₂Ph] (M = Mo, W, R = H, Me, R′ = Mes, tBu) 4 — 8 can be prepared by reaction of halfsandwich complexes [(η⁵‐C₅R₅)M(NR′)₂Cl] with phenyl lithium in good yields. Starting from phenyl complexes 4 — 8 as well as from previously described methyl compounds [(η⁵‐C₅Me₅)M(NtBu)₂Me] (M = Mo, W), reactions with aqueous HCl lead to imido(oxo) methyl and phenyl complexes [(η⁵‐C₅Me₅)M(NtBu)(O)(R)] M = Mo, R = Me ( 9 ), Ph ( 10 ); M = W, R = Ph ( 11 ) and dioxo complexes [(η⁵‐C₅Me₅)M(O)₂(CH₃)] M = Mo ( 12 ), M = W ( 13 ). Hydrolysis of organometal imides with conservation of M‐C σ and π bonds is in fact an attractive synthetic alternative for the synthesis of organometal oxides with respect to known strategies based on the oxidative decarbonylation of low valent alkyl CO and NO complexes. In a similar manner, protolysis of [(η⁵‐C₅H₅)W(NtBu)₂(CH₃)] and [(η⁵‐C₅Me₅)Mo(NtBu)₂(CH₃)] by HCl gas leads to [(η⁵‐C₅H₅)W(NtBu)Cl₂(CH₃)] 14 und [(η⁵‐C₅Me₅)Mo(NtBu)Cl₂(CH₃)] 15 with conservation of the M‐C bonds. The inert character of the relatively non‐polar M‐C σ bonds with respect to protolysis offers a strategy for the synthesis of methyl chloro complexes not accessible by partial methylation of [(η⁵‐C₅R₅)M(NR′)Cl₃] with MeLi. As pure substances only trimethyl compounds [(η⁵‐C₅R₅)M(NtBu)(CH₃)₃] 16 ‐ 18 , M = Mo, W, R = H, Me, are isolated. Imido(benzylidene) complexes [(η⁵‐C₅Me₅)M(NtBu)(CHPh)(CH₂Ph)] M = Mo ( 19 ), W ( 20 ) are generated by alkylation of [(η⁵‐C₅Me₅)M(NtBu)Cl₃] with PhCH₂MgCl via α‐H abstraction. Based on nmr data a trend of decreasing donor capability of the ligands [NtBu]^2— > [O]^2— > [CHR]^2— ? 2 [CH₃]^— > 2 [Cl]^— emerges.     

Kombination von Ionenaustausch und Gefriertrocknung als Syntheseweg zu neuen Oxoferraten(VI) M2FeO4 mit M = Li,Na, N(CH3)4, N(CH3)3Bzl,N(CH3)3Ph

Combination of Ion Exchange and Freeze Drying as a Synthetic Route to New Oxoferrates(VI) M₂FeO₄ with M = Li, Na, N(CH₃)₄, N(CH₃)₃Bzl, N(CH₃)₃Ph For the first time Oxoferrates(VI) M₂FeO₄ with M = Li, Na, N(CH₃)₄, N(CH₃)₃Bzl and N(CH₃)₃Ph have been prepared by cation exchange reaction on K₂FeO₄ and freeze drying of the resulting aqueous solutions. Li₂FeO₄ crystallizes as a monohydrate and decomposes at –10 ± 3 °C. Na₂FeO₄ crystallizes orthorhombically (Cmcm, a = 5.675(3) Å, b = 9.349(4) Å, c = 7.160(2) Å) and is isostructural to Na₂CrO₄. [N(CH₃)₄]₂FeO₄ crystallizes tetragonally (P4/nbm, a = 11.010(3) Å, c = 10.902(4) Å) and is isostructural to the room temperature modification of [N(CH₃)₄]₂SO₄. Infrared spectra of the alkylammonium ferrates(VI) show a decreasing influence of lattice forces on the vibrations of the FeO₄^2– ions with increasing cation size. Magnetic measurements show the expected paramagnetism for a d² ion.     

Synthesis and Reactivity of Phenylimidorhenium(V) Complexes with N‐[(N′,N′‐Dialkylamino)(thiocarbonyl)]benzamidines. Observation of a pH‐Dependent Isomerisation of Related Oxorhenium(V) Compounds

Reactions of [Re(NPh)Cl₃(PPh₃)₂] with N‐[(N′,N′‐dialkylamino)(thiocarbonyl)]benzamidines (H₂R₂tcb) (R₂ = Et₂, (CH₂)₂O(CH₂)₂) in methanol give mono‐chelates of the composition [Re(NPh)Cl₂(PPh₃)(HR₂tcb)] as the sole products independent of the amount of the added H₂R₂tcb. Addition of a supporting base such as NEt₃ results in hydrolysis of the Re=NPh bonds and partial hydrolysis of the thiocarbamoylbenzamidines. Orange‐brown, cationic oxorhenium(V) compounds of the formula [ReO(HR₂tcb)₂]Cl were isolated from such reaction mixtures in good yields, and the formation of small amount of the unusual sulfido/persulfido‐bridged Re^V dimer [{ReO(HEt₂tcb)}₂(μ‐S)(μ‐S₂)] give evidence for a considerable degree of ligand decomposition under such conditions. The products have been characterized by spectroscopic methods and X‐ray crystallography. Acidification of orange‐brown solutions of the five‐coordinate Re^V oxo complex [ReO(HEt₂tcb)₂]Cl causes an immediate change of the color and deep blue crystals of the neutral, six‐coordinate [ReOCl(HEt₂tcb)₂] can be isolated from the resulting mixture. Alternatively, the product can be prepared by a ligand‐exchange protocol starting from (NBu₄)[ReOCl₄] and H₂Et₂tcb. The pH‐dependent isomerization between [ReO(HEt₂tcb)₂]Cl and [ReOCl(HEt₂tcb)₂] is reversible.     

Na9[FeO3][FeO4] ein gemischtvalentes Oxoferrat(II,III) mit isolierten [FeO3]4— — und [FeO4]5— ‐Anionen

Na₉[FeO₃][FeO₄]a Mixed Valent Oxoferrat(II, III) with Isolated [FeO₃]^4— — and [FeO₄]^5— Anions Na₉[FeO₃][FeO₄] has been formed and obtained from a redox reaction between CdO and iron metal (reaction container) and Na₂O in the presence of NaOH at 450 °C as orange‐red transparent single crystals. The crystal structure determination (IPDS data: Pca2₁, a = 956.2(2) pm, b = 999.1(2) pm, c = 1032.3(2) pm, Z = 4, R_all = 0.0455) reveals the presence of isolated complex anions, [FeO₃]^4— and [FeO₄]^5—.     

Oxorhenium(V) Complexes with Thiosemicarbazones

Neutral oxorhenium(V) complexes with thiosemicarbazones derived from 2‐pyridine formamide, HL¹, are formed when [ReOCl₃(PPh₃)₂] reacts with equimolar amounts of the ligands. Reduction of the metal and the formation of rhenium(III) complexes of the composition [Re(L¹)₂]⁺ occurs when an excess of thiosemicarbazones is used and the reaction is performed in boiling toluene for a prolonged period of time. The thiosemicarbazones deprotonate and act as tridentate ligands as has been confirmed by an X‐ray structure of [ReOCl₂(L^1b)], where HL^1b is 2‐pyridineformamide‐N(4)‐ethylthiosemicarbazone and the ligand occupies the equatorial coordination sphere of the complex together with one of the chloro ligands.     

Synthese,EPR und Röntgenkristallstrukturanalyse von mer-Trichloro(2,2′-bipyridin)nitridotechnetium(VI), einem neuen Nitridokomplex des Technetium(VI)

Synthesis, EPR and X-Ray Structure of mer-Trichloro(2,2′-bipyridine)nitridotechnetium(VI) — a new Technetium(VI) Nitrido Complex mer-Trichloro(2,2′-bipyridine)nitridotechnetium(VI) has been prepared by the reaction of (NBu₄)[TcNCl₄] with 2,2′-bipyridine in acetonitrile, whereas the same procedure gives in methanol the technetium(V) cation [TcNCl(bipy)₂]⁺. The EPR spectrum of [TcNCl₃(bipy)] suggests a meridional coordination of the three chloro ligands. [TcNCl₃(bipy)] crystallizes monoclinic in the space group P2₁/n; a = 8.572(1), b = 15.462(1), c = 10.110(1) Å, β = 104.21(1)°, Z = 4. The R value converged at 0.034 on the basis of 3 040 reflections. The technetium atom is distorted octahedrally coordinated with the chloro ligands meridionally cis with respect to the nitrido nitrogen. The Tc? N(1) bond length is 1.669(4) Å, and the Tc? N(3) bond (2.371(4) Å) is significantly lengthened due to the structural trans labilizing influence of the “N^3?” ligand.     

A New Type of Anionic Framework in Microporous Potassium Iron(II) Phosphate K[Fe(PO4)]

A new iron(II) orthophosphate K[Fe(PO₄)] has been obtained by hydrothermal synthesis and its crystal structure was determined by single‐crystal X‐ray diffraction: space group P2₁/n, Z = 8, a = 9.6199(10), b = 8.6756(8), c = 10.8996(13) Å, β = 115.577(8)° at 193 K, R = 0.023. Fe^II shows coordination numbers (CN) 4 (distorted tetrahedral) and CN 5 (distorted trigonal bipyramidal). The [FeO₄] and [FeO₅] units form together with the [PO₄] tetrahedra a microporous 3D para‐framework with open channels along the a and b directions. The potassium ions positioned in the channels show CN 7 and 8. The structural relations within the morphotropic row of non‐isotypic K[M(PO₄)] structures (M = Zn, Ni, Mn, Fe) are discussed on the basis of common basic structural units.     

Ce2[SeO3]3 and Pr2[SeO3]3: Non‐Isostructural Oxoselenates(IV) of the Light Lanthanoids

The crystal structures of Ce₂[SeO₃]₃ and Pr₂[SeO₃]₃ have been refined from X‐ray single‐crystal diffraction data. The compounds were obtained using stoichiometric mixtures of CeO₂, SeO₂, Ce, and CeCl₃ (molar ratio 3:3:1:1) or Pr₆O₁₁, SeO₂, Pr, and PrCl₃ (molar ratio 3:27:1:2) heated in evacuated sealed silica tubes at 830 °C for one week. Ce₂[SeO₃]₃ crystallizes orthorhombically (space group: Pnma), with four formula units per unit cell of the dimensions a = 839.23(5) pm, b = 1421.12(9) pm, and c = 704.58(4) pm. Its structure contains only a single crystallographically unique Ce³⁺ cation in tenfold coordination with oxygen atoms arranged as single‐face bicapped square antiprism and two different trigonal pyramidal [SeO₃]^2? groups. The connectivity among the [CeO₁₀] polyhedra results in infinite sheets of face‐ and edge‐sharing units propagating normal to [001]. Pr₂[SeO₃]₃ is monoclinic (space group: P2₁/n) with twelve formula units per unit cell of the dimensions a = 1683.76(9) pm, b = 705.38(4) pm, c = 2167.19(12) pm, and β = 102.063(7)°. Its structure exhibits six crystallographically distinct Pr³⁺ cations in nine‐ and tenfold coordination with oxygen atoms forming distorted capped square antiprisms or prisms (CN = 9), bicapped square antiprisms and tetracapped trigonal prisms (CN = 10), respectively. The [PrO₉] and [PrO₁₀] polyhedra form double layers parallel to (111) by edge‐ or face‐sharing, which are linked by nine different [SeO₃]^2? groups to build up a three‐dimensional framework. In both compounds, the discrete [SeO₃]^2? anions (d(Se⁴⁺–O^2?) = 166–174 pm) show the typical Ψ¹‐tetrahedral shape owing to the non‐bonding “lone‐pair” electrons at the central selenium(IV) particles. Moreover, their stereochemical “lone‐pair” activity seems to flock together in large empty channels running along [010] in the orthorhombic Ce₂[SeO₃]₃ and along [101] in the monoclinic Pr₂[SeO₃]₃ structure, respectively.     

Synthesis and Application of a Perfluorinated Ammoniumyl Radical Cation as a Very Strong Deelectronator

The perfluorinated dihydrophenazine derivative (perfluoro‐5,10‐bis(perfluorophenyl)‐5,10‐dihydrophenazine) (“phenazine^F”) can be easily transformed to a stable and weighable radical cation salt by deelectronation (i.e. oxidation) with Ag[Al(OR^F)₄]/ Br₂ mixtures (R^F=C(CF₃)₃). As an innocent deelectronator it has a strong and fully reversible half‐wave potential versus Fc⁺/Fc in the coordinating solvent MeCN (E°′=1.21 V), but also in almost non‐coordinating oDFB (=1,2‐F₂C₆H₄; E°′=1.29 V). It allows for the deelectronation of [Fe^IIICp*₂]⁺ to [Fe^IV(CO)Cp*₂]²⁺ and [Fe^IV(CN‐^tBu)Cp*₂]²⁺ in common laboratory solvents and is compatible with good σ‐donor ligands, such as L=trispyrazolylmethane, to generate novel [M(L)_x]ⁿ⁺ complex salts from the respective elemental metals.     

Synthesis and Reactivity of Structurally Analogous Phenylimido and Oxo Complexes of Rhenium(V) with N,N‐Dialkyl‐N′‐benzoylthioureas

[ReOCl₃(PPh₃)₂] and [Re(NPh)Br₃(PPh₃)₂] react at room temperature with equivalent amounts of N,N‐dialkyl‐N′‐benzoylthioureas (HR¹R²btu) in CH₂Cl₂ under formation of the rhenium(V) complexes [ReOCl₂(R¹R¹btu)(PPh₃)] and [Re(NPh)Br₂(R¹R²btu)(PPh₃)], respectively. The products are structurally analogous with the oxygen atoms of the benzoylthioureas binding in trans positions to the oxo or phenylimido ligands. Prolonged reaction times result in the reduction of the oxo compound by the released PPh₃ and the formation of rhenium(III) complexes of the composition [ReCl₂(PPh₃)₂(R¹R²btu)], while such a second reaction path is excluded for the phenylimido compound. Phenylimido species with more than one N,N‐dialkyl‐N′‐benzoylthioureato ligand could not be isolated, even when a large excess of HR¹R²btu was used during the reaction.     

Sm2As4O9: Ein ungewöhnliches Samarium(III)‐Oxoarsenat(III) gemäß Sm4[As2O5]2[As4O8]

Sm₂As₄O₉: An Unusual Samarium(III) Oxoarsenate(III) According to Sm₄[As₂O₅]₂[As₄O₈] Pale yellow single crystals of the new samarium(III) oxoarsenate(III) with the composition Sm₄As₈O₁₈ were obtained by a typical solid‐state reaction between Sm₂O₃ and As₂O₃ using CsCl and SmCl₃ as fluxing agents. The compound crystallizes in the triclinic crystal system with the space group (No. 2, Z = 2; a = 681.12(5), b = 757.59(6), c = 953.97(8) pm, α = 96.623(7), β = 103.751(7), γ = 104.400(7)°). The crystal structure of samarium(III) oxoarsenate(III) with the formula type Sm₄[As₂O₅]₂[As₄O₈] (≡ 2 × Sm₂As₄O₉) contains two crystallographically different Sm³⁺ cations, where (Sm1)³⁺ is coordinated by eight, but (Sm2)³⁺ by nine oxygen atoms. Two different discrete oxoarsenate(III) anions are present in the crystal structure, namely [As₂O₅]^4? and [As₄O₈]^4?. The [As₂O₅]^4? anion is built up of two Ψ¹‐tetrahedra [AsO₃]^3? with a common corner, whereas the [As₄O₈]^4? anion consists of four Ψ¹‐tetrahedra with ring‐shaped vertex‐connected [AsO₃]^3? pyramids. Thus at all four crystallographically different As³⁺ cations stereochemically active non‐binding electron pairs (“lone pairs”) are observed. These “lone pairs” direct towards the center of empty channels running parallel to [010] in the overall structure, where these “empty channels” being formed by the linkage of layers with the ecliptically conformed [As₂O₅]^4? anions and the stair‐like shaped [As₄O₈]^4? rings via common oxygen atoms (O1 – O6, O8 and O9). The oxygen‐atom type O7, however, belongs only to the cyclo‐[As₄O₈]^4? unit as one of the two different corner‐sharing oxygen atoms.     

Crystal and Species Engineering with Semi‐Flexible Nitrogen Containing Organic Cations: Generation of [H13O6]+ Ions with the Unfavoured Unbranched Topology by Enclosing Hydrochloric Acid in a Porous Inorganic‐Organic Hybrid Material

The reaction of rhodium(III) chloride trihydrate with 1, 4‐diazacycloheptane in concentrated hydrochloric acid results in the formation of tris(1, 4‐diazoniacycloheptane) hexaaquahydrogen(1+) bis(hexachlororhodate(III)) chloride, [C₅H₁₄N₂]₃[H₁₃O₆][RhCl₆]₂Cl ( 1 ). Dark red crystals of 1 are obtained by diffusion‐controlled crystallization at room temperature. Slow evaporation of the mother liquor over a period of several days yields a few tiny crystals of the bis(1, 4‐diazoniacycloheptane) hexachlororhodate(III) chloride hydrate, [C₅H₁₄N₂]₂[RhCl₆]Cl ˙ 1.75 H₂O ( 2 ), as red thin squared plates. In the context of crystal engineering, compounds 1 and 2 are inorganic‐organic hybrid materials built up from octahedral [RhCl₆]^3‐, simple Cl^‐ and semi‐flexible heterocyclic 1, 4‐diazoniacycloheptane ions, incorporating either the [H₁₃O₆]⁺ and further Cl^‐ ions or portions of simple water molecules. Both compounds crystallize in the space group type P2₁/c. Compound 1 contains isolated [H₁₃O₆]⁺ ions with a linear chain‐like configuration enclosed in the cavities of the inorganic‐organic framework. The presence of a strong central O···H···O hydrogen bond within the [H₁₃O₆]⁺ ions in 1 is confirmed by the short O···O separation of 2.47Å and by characteristic IR absorption bands at 1626 (s), ～ 1250 (m) and 668 (m) cm^‐1. During the thermal decomposition, compound 1 looses at first five equivalents of water and one equivalent of hydrochloric acid in a two‐step process at 37 °C and 67 °C. This is followed by the decomposition of the 1, 4‐diazoniacycloheptane cations and the hexachlororhodate(III) anions, starting at 190 °C and proceeding intensified at 240 °C.     

Synthesis,Structure and Characterization of Dinuclear Pentacoordinate Molybdenum(V) Complexes with Thiosemicarbazone Ligands

New dinuclear pentacoordinate molybdenum(V) complexes, [Mo₂^VO₃L₂] [L = thiosemicarbazonato ligand: C₆H₄(O)CH:NN:C(S)NHR′ and C₁₀H₆(O)CH:NN:C(S)NHR′; R′ = H, CH₃, C₆H₅) were obtained either by oxygen atom abstraction from Mo^VIO₂L with triphenylphosphine or by using [Mo₂O₃(acac)₄] in the reaction with the corresponding ligands H₂L. Crystal and molecular structure of [Mo₂O₃{C₆H₄(O)CH:NN:C(S)NHC₆H₅}₂] · CH₃CN has been determined by the single‐crystal X‐ray diffraction method.     

Syntheses and Structures of μ-Oxo-Bis[dichloroiron(III)]-Bis-[2,6-Diacetylpyridinedioximate(-1)]Iron(II) and Related Compounds

The syntheses and structures of four new compounds are described. Two of these compounds are the anhydrous and dihydrate chloride salts of the diamagnetic bis(2,6-diacetylpyridinedioxime)iron(II) cation, [Fe(DAPDH₂)₂]²⁺. In this complex cation the DAPDH₂ ligand binds to the iron, as expected, through its three nitrogen atoms leaving the four oxime oxygen atoms protonated and uncoordinated. The third compound is (AsPh₄)₂[Fe₂OCl₆], a new salt of the well-known oxo-bridged diiron complex, [Fe₂OCl₆]^2?. The synthesis of (AsPh₄)₂[Fe₂OCl₆] is a high yield, straightforward, one-step preparation starting with AsPh₄Cl and ferrous chloride in methanol. In this synthesis Fe(II) is oxidized to Fe(III) by atmospheric O₂. The fourth new compound is the novel and unexpected triiron complex [Fe(DAPDH)₂Fe₂OCl₄]. This complex is derived from [Fe(DAPDH₂)₂)]²⁺ and [Fe₂OCl₆]^2? by removing the H⁺ from each of two adjacent oxime oxygen atoms of the former and one Cl^? from each of the Fe(III) ions of the latter. The resulting neutral fragments, Fe(DAPDH)₂ and Fe₂OCl₄, are joined via bonds linking the two oxime oxygen atoms to the two Fe(III) ions giving rise to an unusual eight membered chelate ring containing three iron ions, two nitrogen atoms and three oxygen atoms, one of which is the bridge between the two Fe(III) ions.     

Oxorhenium(V) Complexes with 1,3,4‐Triphenyl‐1,2,4‐triazol‐5‐ylidene

Reactions of the oxorhenium(V) complexes [ReOX₃(PPh₃)₂] (X = Cl, Br) with the N‐heterocyclic carbene (NHC) 1,3,4‐triphenyl‐1,2,4‐triazol‐5‐ylidene (L^Ph) under mild conditions and in the presence of MeOH or water give [ReOX₂(Y)(PPh₃)(L^Ph)] complexes (X = Cl, Br; Y = OMe, OH). Attempted reactions of the carbene precursor 5‐methoxy‐1,3,4‐triphenyl‐4,5‐dihydro‐1H‐1,2,4‐triazole ( 1 ) with [ReOCl₃(PPh₃)₂] or [NBu₄][ReOCl₄] in boiling xylene resulted in protonation of the intermediately formed carbene and decomposition products such as [HL^Ph][ReOCl₄(OPPh₃)], [HL^Ph][ReOCl₄(OH₂)] or [HL^Ph][ReO₄] were isolated. The neutral [ReOX₂(Y)(PPh₃)(HL^Ph)] complexes are purple, airstable solids. The bulky NHC ligands coordinate monodentate and in cis‐position to PPh₃. The relatively long Re–C bond lengths of approximate 2.1Å indicate metal‐carbon single bonds.     

Self‐assembly and Cycling of a Three‐state PdxLy Metallosupramolecular System

The use of stimuli to induce reversible structural transformations in metallosupramolecular systems is of keen interest to chemists seeking to mimic the way that Nature effects conformational changes in biological machinery. While a wide array of stimuli have been deployed towards this end, stoichiometric changes have only been explored in a handful of examples. Furthermore, switching has generally been between only two distinct states. Here we use a simple 2‐(1‐(pyridine‐4‐methyl)‐1H‐1,2,3‐triazol‐4‐yl)pyridine “click” ligand in combination with Pd^II in various stoichiometries and concentrations to quantitatively access and cycle between three distinct species: a [PdL₂]²⁺ monomer, a [Pd₂L₂]⁴⁺ dimer, and a [Pd₉L₁₂]¹⁸⁺ cage.     

New Ionic Liquid Compounds Based on Tantalum Pentachloride TaCl5: Synthesis,Structural, and Spectroscopic Elucidation of the (μ‐Oxido)‐Chloridotantalates(V) [BMPy][TaCl6], [BMPy]4[(TaCl6)2(Ta2OCl10)], and [EMIm]2[Ta2OCl10]

1‐Butyl‐4‐methylpyridinium hexachloridotantalate(V), [BMPy][TaCl₆] ( 1 ), tetrakis(1‐butyl‐4‐methylpyridinium) bis(hexachloridotantalate(V) (μ‐oxido)‐decachloridotantalate(V), [BMPy]₄[(TaCl₆)₂(Ta₂OCl₁₀)] ( 2 ), and bis(1‐ethyl‐3‐methylimidazolium)‐(μ‐oxido)‐decachloridoditantalate(V), [EMIm]₂[Ta₂OCl₁₀] ( 3 ) were synthesized and characterized by single‐crystal X‐ray diffraction and vibrational spectroscopy. Compounds 1 and 3 crystallize in the monoclinic space group P2₁/c (no. 14), whereas compound 2 crystallizes in the triclinic space group P (no. 2). All compounds are built up by the mentioned bulky organic cations and octahedral [TaCl₆]^– respective linear [Ta₂OCl₁₀]^2– anions. Coulomb interactions are dominant between the ionic species. FT‐IR and FT‐Raman spectra were recorded and interpreted, especially with respect to the inorganic species [TaCl₆]^– (O_h) and [Ta₂OCl₁₀]^2– (C_i symmetry, approximately D_4h). The melting temperatures of compounds 1 – 3 are given.     

Ca2+‐Induced Oxygen Generation by FeO42− at pH 9–10

Although FeO₄^2? (ferrate(IV)) is a very strong oxidant that readily oxidizes water in acidic medium, at pH 9–10 it is relatively stable (<2 % decomposition after 1 h at 298 K). However, FeO₄^2? is readily activated by Ca²⁺ at pH 9–10 to generate O₂. The reaction has the following rate law: d[O₂]/dt=k_Ca[Ca²⁺][FeO₄^2?]². ¹⁸O‐labeling experiments show that both O atoms in O₂ come from FeO₄^2?. These results together with DFT calculations suggest that the function of Ca²⁺ is to facilitate O–O coupling between two FeO₄^2‐ions by bridging them together. Similar activating effects are also observed with Mg²⁺ and Sr²⁺.     

ChemInform Abstract: At the Border of Intermetallic Compounds and Transition‐Metal Oxides: Crystal Intergrowth of the Zintl Phase Cs4Ge9 and Cs2WO4 or Cs3VO4 as well as Nine‐Atom Cluster Relocation in the Solid State.

Compounds (III) and (VI) containing [Ge₉]^4‐ clusters and oxometallate anions WO₄^2‐ or VO₄^3‐ are characterized by single crystal XRD and Raman spectroscopy.     

Complexes of Group 12 Metal Dihalides with 2‐Acetylpyridine‐N‐oxide 4N‐methylthiosemicarbazone (H4MLO). The Crystal Structures and Organization of [Zn(H4MLO)X2] (X = Br,I)

Reaction of group 12 metal dihalides with 2‐acetylpyridine‐N‐oxide ⁴N‐methylthiosemicarbazone (H4MLO) in ethanol afforded compounds [M(H4MLO)X₂] (M = Zn^II, Cd^II, Hg^II; X = Cl, Br, I), the structures of which were characterized by elemental analysis and by IR and ¹H and ¹³C NMR spectroscopy. In addition, the complexes of ZnBr₂ and ZnI₂ were analysed structurally by X‐ray diffractometry. In [Zn(H4MLO)Br₂] the ligand is O,N,S‐tridentate and the metal is pentacoordinated, while in [Zn(H4MLO)I₂] the thiosemicarbazone is S,O‐bis‐monodentate and the Zn^II cation has a distorted tetrahedral coordination polyhedron. In assays of antifungal activity against Aspergillus niger and Paecilomyces variotii, only the mercury compounds showed any activity, and only [Hg(H4MLO)Cl₂] and [Hg(H4MLO)I₂] were competitive with nystatin against A. niger.