Beiträge zur chemie des bors: 132. 1-phospha- und 1-arsa-4-bora-cyclohexadiene-2,5

The radical-initiated hydrophosphination and hydroarsination of diethylamino-dialkynylboranes with C₆H₅EH₂ (E = P, As) give the compounds 1-phospha- and 1-arsa-4-boracyclohexadienes-2,5 (IV and V, respectively). V is further reduced by C₆H₅AsH₂ to its dihydro derivative. Rather narrow boundaries exist for a substitution chemistry at the BN bond in IVa/IVb: methanolysis yields the B-methoxy derivative which in turn can be converted into the t-butyl compound. Alkali metals cleave the exocyclic PC bond. The anion formed reacts with RX yielding P-alkyl derivatives. Chalcogens convert the phosphorus(III) derivatives into phosphorus(V) compounds.     

Electron impact induced fragmentation of 4-alkyl derivatives of 2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane and the corresponding 1-oxides, 1-sulfides and 1-selenides

The electron impact fragmentations of several derivatives of 2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane have been examined by means of high resolution and metastable ion analysis. The principal fragmentation route for bicyclophosphites, phosphates and phosphorothionates involves a loss of formaldehyde, followed by a loss of the PO₂X and HPO₂X groups (X = -, O, S). The behaviour of phosphoroselenates is quite different, due partly to the favoured loss of selenium from the molecular ion before further fragmentation. Fragmentation through C? O bond breaking and a rearranged molecular ion is dependent on the exocyclic chalcogen atom (-, O, S, Se) on phosphorus. The reactions have been rationalized in terms of 1- and 4-substitutions.     

Remarkably strong polarization of amidine fragment in the crystals of 1-imino-1H-isoindol-3-amine

Results of the X-ray diffraction studies of 1-imino-1H-isoindol-3-amine and its derivatives reveal unusual distribution of bond lengths within the NH₂–C=N amidine fragment in the considered crystals. In the crystal phase, single C–N bond is shorter or at most has the same length as double C=N bond, while in isolated molecules both these bonds have expected lengths, according to the calculations by MP2/6-311G(d,p) and MP2/cc-pvtz methods. It is demonstrated that so unusually strong polarization of the amidine fragment is induced by polar environment in solid state. This effect stabilizes the amino-imino tautomer of 1-imino-1H-isoindol-3-amine, which becomes more stable than the diimino tautomer possessing the lowest energy in the gas phase.     

Synthesis and reactivity with M(II) (M=Co and Cu) chloride of 1-[(2-carboxyethyl)benzene]-3-[benzothiazole]triazene

Reaction of ethyl anthranilate, sodium nitrite, and 2-aminobenzothiazole produces a new triazenide compound, 1-[(2-carboxyethyl)benzene]-3-[benzothiazole]triazene (HL), which has been characterized by X-ray crystallography and NMR spectrum. In the presence of Et₃N, reaction of HL and CuCl₂?·?2H₂O or CoCl₂?·?6H₂O in THF/methanol affords a tetranuclear copper(II) complex [Cu₄L₄(µ-OMe)₄]?·?4THF (1) and a cobalt(III) complex [CoL′₃] (2) (L′ is 1-[benzothiazole] triazene ion), accompanied by C–N bond cleavage of HL. They are characterized by X-ray crystallography and magnetic susceptibility measurement. Magnetic studies indicate significant antiferromagnetic coupling between the copper(II) centers for 1. The value obtained for the coupling constant J is ?585?cm^?1.     

7‐Amino‐1‐(2‐deoxy‐β‐erythro‐pentofuranosyl)‐1H‐1,2,3‐triazolo[4,5‐d]pyrimidine: an 8‐azaadenine nucleoside with the nucleobase in a syn conformation

The title compound, C₉H₁₂N₆O₃, shows a syn‐glycosylic bond orientation [χ = 64.17 (16)°]. The 2′‐deoxyfuranosyl moiety exhibits an unusual C1′‐exo–O4′‐endo (₁T⁰; S‐type) sugar pucker, with P = 111.5 (1)° and τ_m = 40.3 (1)°. The conformation at the exocyclic C4′—C5′ bond is +sc (gauche), with γ = 64.4 (1)°. The two‐dimensional hydrogen‐bonded network is built from intermolecular N—H...O and O—H...N hydrogen bonds. An intramolecular bifurcated hydrogen bond, with an amino N—H group as hydrogen‐bond donor and the ring and hydroxymethyl O atoms of the sugar moiety as acceptors, constrains the overall conformation of the nucleoside.     

CRYSTAL STRUCTURE OF THE NOVEL COMPOUND (1α, 3bT, 5α)-1,3-DIPHENYL-5-HYDRIDO-5-ISOPROPOXY-1λ6, 3λ6,2,4,6,5λ5-DITHIATRIAZAPHOSPHORINE-1,3-DIOXIDE. A COMPARISON WITH RELATED STRUCTURES

Abstract

The title compound (1α, 3β, 5α)-(NSOPh)₂NP(H)O-i-Pr crystallizes in the spacegroup P2₁/n with cell dimensions: a = 12. 150(2), b = 8.911(1), c = 17.614(3) Å, β = 107.52(1)^o; Z = 4. The structure was solved by direct methods and refined by least-squares techniques to an R value of 0.048 for 2420 independent reflections (collected at room temperature) with I > 2.5 σ(I). The unit cell contains dimeric units which are formed by unprecedented P[sbnd]H…O[dbnd]S bridges. The conformation of the inorganic ring skeleton can be described as a boat; phosphorus and sulfur atoms show a distorted tetrahedral geometry. The S[sbnd]N bond lengths differ slightly, ranging from 1.547(3) to 1.588(2) Å. The exocyclic bond lengths are P[sbnd]H = 1.34(2), P[sbnd]O = 1.553(2), S[sbnd]O = 1.439(2) (mean value), and S[sbnd]C = 1.767(4) (mean value) Å. From a comparison with analogous structures the degree of asymmetry (ΔI = {[P[sbnd]N]-[S[sbnd]N]}Å) in the SNP unit is related to the difference in electronegativity between the sulfur and phosphorus centres.     

Acyl- und Alkylidenphosphane. XXVIII. Synthese und Struktur von 1,3-Dibenzyl- und 1,3-Diethyl-2,4-bis(phenylimino)-1,3-diphosphetan

Acyl- and Alkylidenephosphines. XXVIII. Synthesis and Structure of 1,3-Dibenzyl- and 1,3-Diethyl-2,4-bis(phenylimino)-1,3-diphosphetane Catalyzed by small amounts of solid sodium hydroxide, the adducts 1a and 1b formed from benzyl- or ethylbis(trimethylsilyl)phosphine and phenylisocyanate, react at +20°C slowly to give hexamethldisiloxane and oligomeric [(phenylimino)methylidene]phosphines. In different solvents the benzyl compound was found to exist only as a mixture of [N,N′-(E)/(Z)]-isomeric 2,4-bis-(phenylimino)-1,3-diphosphetanes 2a with their alkyl groups at the phosphorus atoms in trans position, whereas in case of the ethyl derivative 2b a second pair of [N,N′-(E)/(Z)]-isomeric dimers with their substituents in cis position and two trimeric forms ( 3b and 4b ) could be detected in cyclopentane. [N,N′-(E)]-1r,3t-dibenzyl- ( 2a ) and [N,N′-(E)]-1r,3t-diethyl-2,4-bis(phenylimino)-1,3-diphosphetane 2b isolated from 1,2-dimethoxyethane or cyclopentane, crystallize in the monoclinic space group P2₁/c or P2₁/n, resp., with following dimensions of the unit cell determined at temperatures of measurement of +20 ± 3°C/?130 ± 3°C: a = 2145.4(1)/569.3(1); b = 568.1(2)/719.1(2); c = 1960.2(2)/2042.6(4) pm; β 99.43(1)°/95.03(2)°; Z = (2+2) and 2, resp. X-ray structure determinations (R_w = 0.034/0.041) show both molecules to be centrosymmetric. Characteristic rounded bond lengths (pm) and angles (°) are: endocyclic P? C 185/184; C? P? C 82/81; P? C? P 98/99; exocyclic P? C 186/184; C?N l27/127; C?N? C 121/11.     

Efficient Synthesis of Novel 3-[5-(1H-Benzimidazol-2-Ylmethanesulfonyl)-4-Phenyl-4H-(1,2,4)Triazol-3-Yl]-1H-(1,8)Naphthyridin-4-One Derivatives

Abstract

of 1,4-dihydro-4-oxo-1,8-naphthyridine-3-carbohydrazide (4) with substituted phenyl isothiocyanates (5) in ethanol under reflux for 30 min gave thiosemicarbazide derivatives 6, which on cyclization in 2N NaOH under refluxing conditions for 1 h resulted in 3-(5-mercapto- 4-phenyl-4H-1,2,4-triazol-3-yl)-1,8-naphthyridin-4(1H)-one (7). Alternatively, 7 could also be prepared from following sequence of reactions, i.e., 4 → 8 → 7. In another sequence of reactions, condensation of 7 with chloroacetic acid in dimethylformamide (DMF) and K₂CO₃ as a mild base at 120 °C for 2 h resulted in 2-((5-(1,4-dihydro-4-oxo-1,8-naphthyridin-3-yl)-4-phenyl-4H-1,2,4-triazol-3-yl)sulfanyl)acetic acid (10). The latter, on reaction with substituted o-phenylenediamine (11) in 6N HCl for 4 h yielded 3-(5-((1H-benzo[d]imidazol-2-yl)methylthio)-4-phenyl-4H-1,2,4-triazol-3-yl)-1,8-naphthyridin-4(1H)-one (12). Alternatively, 12 could also be prepared by reacting 7 with 13 in DMF and K₂CO₃ as a mild base at 120 °C for 2 h, followed by oxidation with H₂O₂ resulting in the corresponding sulfonyl derivatives 14.     

Synthesis, spectroscopic properties and crystal structure determination of 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole derivatives

Substituted 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole derivatives 2, 3 and 6 were synthesized. 2-(2-Pyridin-4-yl-vinyl)-1H-benzimidazole 2 and 6-methyl-2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 3 were prepared by condensation reaction from 3-pyridin-4-yl-acrylic acid and corresponding 1,2-phenylenediamines in polyphosporic acid (PPA). 2,7,11-b-Triaza-benzo[c]fluorene 4 was prepared by photochemical dehydrocyclization reaction of ethanolic solution of 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 2. 2-(2-Pyridin-4-yl-vinyl)-3H-benzimidazole-6-carbonitrile 6 was prepared by condensation reaction from 3-pyridin-4-yl-propenal and 4-cyano-1,2-phenylenediamine using p-benzoquinone as oxidants. The structure of novel benzimidazole derivatives has been studied by ¹H and ¹³C NMR, IR, MS, UV/Vis and fluorescence spectroscopy. The structure of 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 2 was confirmed by X-ray single crystal structure analysis. The conformation of the molecule is E in regard to substituents position around vinyl double C=C bond. The non-planar molecules are mutually connected via the N–H···N and C–H···N type of intermolecular hydrogen bonds into infinite chains spreading along y axis.     

Synthesis,spectral and antimicrobial studies of chloroantimony(III)di[3(2′-hydroxyphenyl)-5-(4-substitutedphenyl)pyrazolinates]

Dichloroantimony(III) pyrazolinates and chloroantimony(III) dipyrazolinates of the type SbCl₂(C₁₅H₁₂N₂OX) and SbCl(C₁₅H₁₂N₂OX)₂ [where C₁₅H₁₂N₂OX = 3(2′-hydroxyphenyl)-5-(4-X-phenyl)pyrazoline, X=H in1 and5;–CH₃ in2 and6;–OCH₃ in3 and7 and–Cl in4 and8] have been synthesized by reaction of SbCl₃ and sodium salt of pyrazolines in 1 : 1 and 1 : 2 molar ratio in anhydrous benzene at elevated temperature. These newly synthesized derivatives have been characterized by elemental analysis (C, H, N, Cl and Sb), molecular weight measurement and spectral studies [IR and¹H and¹³C NMR]. The free pyrazoline and some dichloroantimony(III) pyrazolinates and chloroantimony(III) dipyrazolinates have been screened for antibacterial and antifungal activities, with some dichloroantimony(III) pyrazolinates and chloroantimony(III) dipyrazolinates exhibiting higher antibacterial and antifungal effects than free pyrazoline and some antibiotics.     

3-Substituted Sydnone Derivatives. Structures of 3-Cyclohexylsydnone and of Two Forms of 3-(3-Pyridyl)sydnone

The crystal and molecular structures of three sydnone derivatives are reported. The compound 3-cyclohexylsydnone crystallizes in space group C2/c of the monoclinic system with sixteen molecules in a cell of dimensions a = 19.326 (3), b = 9.471 (2), c = 20.005 (4)Å, β = 106.85(1)°. The structure has been refined to a final value of 0.0581 for the conventional R-factor based on 2222 independent observed intensities. Form I of 3-(3-pyridyl)sydnone crystallizes in space group P2/n of the monoclinic system with eight molecules in a cell of dimensions a = 7.317(2), b = 9.283 (2), c = 20.891 (6) Å, β = 99.61(2)°. The structure has been refined to a final value of 0.0514 for the conventional R-factor based on 1208 independent observed intensities. Form II of 3-(3-pyridyl)sydnone crystallizes in space group P2₁/c of the monoclinic system with eight molecules in a cell of dimensions a=9.073 (2), b = 22.267 (5). c = 7.494(2)Å, β = 112.15 (2)°. The structure has been refined to a final value of 0.0462 for the conventional R-factor based on 1330 independent observed intensities. Each of the three structures contains two crystallographically independent molecules in the cell. In the case of 3-cyclohexylsydnone, one of the independent molecules exhibits disorder around the exocyclic bond at N(3). A comparison of bond lengths indicates that the (electron donating) cyclohexyl group brings about enhanced electron density in the N(3)-C(4) bond, and possibly in the N(3)-N(2) bond. All three structures studied here exhibit intermolecular hydrogen bonding involving C(4)-H(4)…O(6) interactions. Although there are no stacking interactions in the cyclohexyl derivative, there is evidence for such interactions in the 3-pyridyl derivatives.     

The substituent effect on mesomorphic properties of 4-octyloxyphenyl 4-(4-R-3-nitrobenzoyloxy)benzoates and 4-(4-octyloxybenzoyloxy)phenyl 4-R-3-nitrobenzoates

Abstract

The thermal properties of 4-octyloxyphenyl 4-(4-R-3-nitrobenzoyloxy) benzo-ates (1) and 4-(4-octyloxybenzoyloxy)phenyl 4-R-3-nitrobenzoates (2) have been examined, where R = hydrogen, halogens, alkyl and alkoxy groups. The derivatives of compound 1 incorporating hydrogen, halogens, methoxy and nitro groups show a smectic A phase having a bilayer arrangement, and the others with a long alkoxy group show the S_A phase with the monolayer arrangement. The derivatives of compound 2 incorporating halogens, and the nitro group show the S_A phase with the monolayer arrangement. The alkoxy derivatives show a smectic C phase as well as the nematic phase. The nitro group at the lateral position tends to increase the ratio of the S_A-N transition temperature to the N-I. The effect of the nitro group on the smectic properties has been discussed in terms of the structural and electrostatic nature of the nitro group.     

Recherches sur la formation et la transformation des esters LXXXII [1]. Sur la différenciation entre structures δ2-amino-2 ou imino-2 dans des composés S,N-hétérocycliques pentagonaux et hexagonaux à cycle par ailleurs saturé

Comparison of the NMR. spectra in CDCl₃ of the heterocyclic bases obtained from the cyclisation of ω-(N-thiocarbamoylamino) ethyl (or propyl)-alcohols (or their orthophosphoric or sulfuric monoesters) to those of model compounds II (n = 1 or 2) and III (n = 1 or 2) has shown that: (1) In the case of five membred rings the C?N double bond is always endocyclic (Ib, n = 1) should R be aromatic, araliphatic or aliphatic; (2) In the case of six membered rings the C?S double bond is cnclocyclic when R is aliphatic or araliphatic (Ib, n = 2), and exocyclic when R is aromatic (I a, n = 2), with the exception of 2-(o-carboxyphcnylamino)-dihydro-δ²-m (Ib, n = 2, K = o-carboxyphcnyle). In CF, COOH, all five membered rings (I b, n = 1) show a triplet for the C-4 methylenic protons, whereas all the six membered rings (Ia or I b, n = 2) with the exception of I b, n = 2, R = o-carboxyphenyle, are represented b y a double triplet for the C-4 protons (samt. protonated spccics). Only one triplet is observed when the 3 position is substituted. Thiocarbamoylation of hydrazinoethanol or its orthophosphoric or sulfuric monoesters canoccur at either of the two nitrogen atoms, thus yielding upon cyclization five- (IT′) or six-membered rings (Va or Vb). The NMR spectra of compounds I V in (CIl,), SO show a singlet for 2 amino pro-tons (3-amino) and there is no further structural problem. The NMR spectra of compounds T′ in (CT), SO show a triplet for one amino proton coupling with the neighboring methylenic protons. I n this case, mode1 compounds are needed to assign the position of the C?N double bond ( e x cyclic V a or cndocyclic V b). When R = o-carboxyphenylc, the C?N double bond is probably endoc, yclic (Vb) because this ccimpound and 2-(o-carboxyphenvlarnino)-dihydro-δ² have very similar UV spectra.     

Molecular structure and conformational analysis of chirai (−)-3-(4-bromobenzylidene)-1-isopropyl-2-methoxy-4-methylcyclohexene

(–)-3-(4-Bromobenzylidene)-1-isopropyl-2-methoxy-4-methylcyclohexene, capable of inducing spiral supramolecular ordering when introduced to nematic and some smectic mesophases, has been studied by an X-ray structural analysis. The crystals are orthorhombic; at 20 °Ca = 6.055(1),b = 13.282(3),c=20.734(4) Å,V=1668(1) ų,d _calc = 1.380 g cm^–3, space groupP2 ₁2₁2₁ Z=4. The cyclohexene ring has a conformation intermediate between a sofa and a half-chair. The methyl and methoxyl groups are in asyn orientation with respect to the mean plane of the cycle. The angle between the plane of the aryl substituent and the exocyclic double bond is 33°. The observed distortions of bond angles at unsaturated carbon atoms are typical of derivatives of benzylidenecyclohexene. Molecular mechanics calculations demonstrated that the conformation observed in the crystalline state is not the most favorable, and this conformation is stabilized through intermolecular interactions upon stacking in crystals. It was shown that the relative orientation of the methyl and methoxyl groups as well as the orientation of the aryl substituent substantially affect the conformation of the cyclohexene ring.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2437–2442, December, 1995.     

Synthesis,Characterization, Antimicrobial Activities,and Structural Studies of Lanthanide (III) Complexes with 1-(4-Chlorophenyl)-3-(4-fluoro/hydroxyphenyl)prop-2-en-1-thiosemicarbazone

Twelve coordinate lanthanide (III) complexes with the general composition [Ln L₃X_n(H₂O)_n] where Ln = Pr(III), Sm(III), Eu (III), Gd (III), Tb (III), Dy (III), X = Cl^?1, NO₃ ^?2, n = 2–7, and L is 1-(4-chlorophenyl)-3-(4-fluoro/hydroxyphenyl)prop-2-en-1- thiosemicarbazone have been prepared. The lanthanide complexes (5) were derived from the reaction between 1-(4-chlorophenyl)-3-(4-fluoro/hydroxyphenyl)prop-2-en-1-thiosemicarbazone (4) with an aqueous solution of lanthanide salt. Chalcone thiosemicarbazone ligand (4) was prepared by the reaction of [1-(4-chlorophenyl)-3-(4-fluoro/hydroxyphenyl)]prop-2-enone (chalcone) (3) with thiosemicarbazide in the presence of hot ethanol. All the lanthanide-ligand 1:3 complexes have been isolated in the solid state, are stable in air, and characterized on the basis of their elemental and spectral data.

Thiosemicarbazone ligands behave as bidentate ligands by coordinating through the sulfur of the isocyanide group and nitrogen of the cyanide residue. The probable structure for all the lanthanide complexes is also proposed. The chalcone thiosemicarbazone ligands and their lanthanide complexes have been screened for their antifungal and antibacterial studies. Some of the synthesized lanthanide complexes have shown enhanced activity compared with that of the free ligand.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis of 3-[4-(1-Benzofuran-2-yl)-1,3-thiazol-2-yl]-2-(4-aryl)-1,3-thiazolidin-4-one Derivatives as Biological Agents

A protocol for the synthesis of 3-[4-(1-benzofuran-2-yl)-1,3-thiazol-2-yl]-2-(4-aryl)-1,3-thiazolidin-4-one derivatives (5a–e) has been developed from 1-(1-benzofuran-2-yl)-2-bromoethanone (2),which served as a key intermediate for the synthesis of the title compounds. The reaction of compound 2 with thiourea furnished 4-(1-benzofuran-2-yl)-1,3-thiazol-2-amine 3, which upon further reaction with various aromatic aldehydes, gave Schiff bases 4a–e. These Schiff bases, when treated with thioacetic acid in the presence of catalytic amount of anhydrous ZnCl₂, yielded thiazolidinone derivatives 5a–e. All the newly synthesized compounds have been characterized by analytical and spectral data and screened for their antimicrobial and analgesic activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Highly enantioselective hydrogenation of exocyclic double bond of N-tosyloxazolidinones catalyzed by a neutral rhodium complex and its synthetic applications

A highly enantioselective synthesis of optically active N-tosyl-4-alkyl-1,3-oxazolidin-2-ones based on the asymmetric hydrogenation of the trisubstituted exocyclic double bond of N-tosyl-4-alkylidene-1,3-oxazolidin-2-ones under the catalysis of neutral [Rh(COD)Cl]₂ (COD=1,5-cyclooctadiene) and (S)-(+)-DTBM-SEGPHOS was developed. The utility of this highly enantioselective reaction was exemplified by the synthesis of optically active amino acids, amino alcohols, and piperidine derivatives.     

Chiral exo-Alkylidenecyclopentanes from (1S,4R)-7,7-Dimethyl-1-vinylbicyclo[2.2.1]heptan-2-one

(1S,4R)-7,7-Dimethyl-1-vinylbicyclo[2.2.1]heptan-2-one oxime in the system (CF₃CO)₂O-CF₃COOH and (1S,4R)-1-(1,2-dibromoethyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-one in the system MeONa-MeOH undergo fragmentation to give exo-alkylidenecyclopentane derivatives, (4R)-4-cyanomethyl-5,5-dimethyl-1-[(1E)-trifluoroacetoxyethylidene]cyclopentane and isomeric (4R)-4-carboxymethyl-1-[(1ZE)-2-methoxyethylidene]-5,5-dimethylcyclopentanes, respectively. The trifluoroacetate derivative undergoes unusual rearrangement, yielding an equilibrium mixture of two isomers with endo- and exocyclic double bond.     

Synthesis and Characterization of 2-Mercapto-1-cyclohexylimidazole–Based Zinc(II) and Cadmium(II) Bromide Complexes: The Crystal Structure of [Zn(Hmim chexyl )2(Br)2] with N–H…Br Intermolecular Hydrogen Bonding Interactions

Reactions of the ligand 2-mercapto-1-cyclohexylimidazole (Hmim^chexyl) with both zinc(II) and cadmium(II) bromides in ethanol solutions afforded 2:1 complexes of the type [M(Hmim^chexyl)₂(Br)₂] (M = Zn 1, and Cd 2) with an MBr₂S₂ configurations. Spectroscopic evidence (FT-IR and ¹H-¹³C NMR) confirms that the exocyclic thione sulfur atoms are the donors in both complexes. Complex 1 crystallizes in a monoclinic system, space group C2/c, a = 16.180(3), b = 10.817(5), c = 13.602(3); α = 90, β = 106.754(17), γ = 90; Z = 4; R1 = 0.0229, wR2 = 0.0554. The coordination geometry about the zinc(II) atom is distorted tetrahedral with average Zn-S and Zn-Br bond lengths of 3.3418(8) and 2.4017(6) Å, respectively. The bromide ions form intermolecular N–H…Br hydrogen bonding with the thione NH groups of the ligand molecule.     

Structural and Physicochemical Characteristics of Tetrabutylammonium Tetrahalogenoferrates(III), [(C4H9)4N][FeBr4−nCln]

A series of tetrahalogenoferrates(III), [FeBr_4?nCl_n]^? (n=0‐4) stabilized with the tetrabutylammonium cation, of general formula [(C₄H₉)₄N][FeBr_4?nCl_n], has been synthesized. The crystal and molecular structure of [(C₄H₉)₄N][FeCl₄] was determined. The iron cation adopts slightly distorted tetrahedral coordination with two opposite angles smaller than tetrahedral one, two equal to tetrahedral and two larger than tetrahedral. The bond valences were computed. The total valence of iron atom is equal to 3.08. In the structure can be found only one hydrogen bond C(1)–H···Cl. Except mentioned there are no unusually intermolecular short contacts between ions existing in the structure. All [(C₄H₉)₄N][FeBr_4?nCl_n] (n=0‐4) compounds are isostructural in solid state. On the basis of conductometric measurements, relative stabilities of the anions have been estimated in methanol (MeOH), dimethyl sulfoxide (DMSO), acetone (AC), acetonitrile (AN) and dichloromethane (CH₂Cl₂) representing both polar (including amphiprotic and aprotic) as well as non‐polar solvents. Further, the dissociation constants of the compounds were calculated from the expanded Pitt's conductivity equation. The results of the conductometric measurements were supported by electronic spectra.