Synthesis of Bis{1,2,4-tri(tert-butyl)cyclopentadienyl}mercury by Transfer of Alkylated Cyclopentadienyl Rings from Bismuth to Mercury (Transmetallation)

Bis{1,2,4-tri(tert-butyl)cyclopentadienyl}mercury 2 has been obtained by sodium amalgam reduction of Chlorobis{1,2,4-tri(tert-butyl)cyclopentadienyl}bismuth. The crystal structure of 2 (P1 , a = 10.564(4) Å, b = 11.8230(10) Å, c = 15.546(4) Å, α = 69.160(10)°, β = 82.49(2)°, γ = 64.100(10)°, V = 1 631.7(8) ų) consists of a linear two-coordinated mercury complex with σ bonded tri(tert-butyl)cyclopentadienyl rings. In solution 2 is fluxional on the NMR time scale even at 165 K.     

Synthese und Struktur von Tetrachloro[4-tert-butyl-2(diphenylphosphanyl-κP-methyl)phenolato-κO]tantal(V), ein neuartiger TaV-Komplex mit einem chelatisierenden Aryloxyphosphanliganden

Synthesis and Structure of Tetrachloro[4- tert -butyl-2(diphenylphosphanyl-κP-methyl)phenolato-κO]tantalum(V), a Novel Ta^V Complex with a Chelating Aryloxy Phosphane Ligand 4-tert-Butyl-2-(diphenylphosphanylmethyl)anisol ( 1 ) is prepared from 2-chlormethyl-4-tert-butylanisol and potassium diphenylphosphide in very good yields as a novel oxygen-phosphorus compound with potentially hemilabile ligand properties. Compound 1 reacts with tantalum pentachloride under cleavage of methylchloride revealing the complex tetrachloro[4-tert-butyl-2-(diphenylphosphanyl-κP-methyl)phenolato-κO]tantalum(V) ( 2 ) with a distorted octahedrally coordinated tantalum atom and a chelating aryloxy phosphane ligand. Complex 2 crystallizes in the tetragonal, chiral space group P4₁2₁2 with a = 11.719(5), c = 37.95(5) Å, V = 5171(7) ų, Z = 8. ³¹P NMR spectroscopic studies of 2 establish the coordination of the phosphane unit to the Ta^V center in solution.     

Synthesis and structural characterization of a binuclear zirconium complex of tetraanionic p-tert-butylthiacalix[4]arene bridged by methanol

A zirconium complex with the p-tert-butylthiacalix[4]arene anion was synthesized and its crystal structure was determined by single-crystal X-ray analysis. The complex [Zr(μ₂-CH₃OH)(p-tert-butylthiacalix[4]arene)]₂·9H₂O (1) belongs to the orthorhombic system, space group Pnnm, with a?=?20.436(16), b?=?12.160(8), c?=?20.305(12)?Å, V?=?6774(7)?ų and Z?=?2. In Complex 1 zirconium coordinates to four phenolic anions of the deprotonated p-tert-butylthiacalix[4]arene and is bridged by two methanol molecules; the p-tert-butylthiacalix[4]arene adopts a cone conformation.     

Synthesis,crystal structure,and magnetism of a dinuclear nickel(II) complex [Ni2(MOBPT)2(N3)4] · 2H2O

A dinuclear nickel(II) complex, [Ni₂(MOBPT)₂(N₃)₄] · 2H₂O (MOBPT = 4-(p-methoxyphenyl)-3,5-bis(pyridine-2-yl)-1,2,4-triazole), has been synthesized and characterized by elemental analysis, UV, IR, ESI-MS, and single crystal X-ray crystallography. The complex crystallizes in triclinic system, space group P 1 with a = 9.877(2) Å, b = 10.396(2) Å, c = 11.975(3) Å, α = 71.638(3)°, β = 74.968(3)°, γ = 64.747(3)°, V = 1044.2(4) ų, Z = 1, R = 0.0371 for 5774 observed reflections. The crystal structure determination shows that the dinuclear Ni₂N₈ unit is almost planar with each Ni²⁺ coordinated by four nitrogens from two MOBPT ligands and two axial azides in a distorted octahedral geometry. Magnetic measurements reveal weak antiferromagnetic exchange in the complex.     

Synthesis of 8-alkylthio- and 8-selanyl-3-tert-butylpyrazolo[5,1-c][1,2,4]triazines

Abstract

Interaction of 8-lithio-3-tert-butyl-4-oxopyrazolo[5,1-c][1,2,4]triazin-1-ide with elemental sulfur or selenium in THF with further in situ alkylation at –97?°C followed by warming to room temperature furnished a series of 3-tert-butyl-8-X-pyrazolo[5,1-c][1,2,4]triazin-4(6H)-ones (X?=?n-BuS, n-BuSe, MeSe, PhCH₂S) in good yields. 8,8'-Diselanediylbis(3-tert-butylpyrazolo[5,1-c][1,2,4]triazin-4(1H)-one) was also isolated as a by-product in these reactions. One-pot interaction of the n-BuSe substituted derivative with diborane/boron trifluoride led to reduction of the 1,2,4-triazine core and partial elimination of the alkylselanyl moiety. The structures of the synthesized products were established on the basis of IR, ¹H, 13C, 2D HMBC ¹H–⁷⁷Se NMR and high resolution mass spectra, as well as X-ray single crystal diffraction analyses. Two of the prepared compounds were also tested for antimicrobial and antifungal activities.     

Hydrothermal synthesis,crystal structures,and blue photoluminescence of two 2-D Ag–1,2,4-triazolate coordination polymers with 4462 topology

Two 2-D metal-organic coordination polymers, {[Ag(NH₂–BPT)] · NO₃} _n (1) and {[Ag(BPT)] · H₂O} _n (2), have been synthesized via self-assembly of AgNO₃ and 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (NH₂–BPT) under hydrothermal conditions by controlling the reaction temperatures. Lower reaction temperature (140°C) led to formation of 1, which crystallizes in the monoclinic system, space group C2/c, a = 24.001(3), b = 15.844(2), and c = 12.981(3) Å, V = 2996.8(6) ų, Z = 8. When the temperature was increased to 180°C, in situ deaminization of the organic ligand led to crystallization of 2 (space group P₂1 /n, a = 7.3106(10), b = 19.633(2), and c = 9.0596(16) Å, V = 1190.2(3) ų, Z = 4). The NH₂–BPT in 1 and BPT in 2 are μ₄ tetradentate utilizing two triazolyl and two pyridyl nitrogens, generating an unusual 2-D layer, in which binuclear Ag(I) motifs and organic ligands are four-connecting nodes that inter-link in 4⁴6² topology. Adjacent 2-D metal-organic layers are linked by a system of hydrogen bonds to form 3-D supramolecular frameworks. Strong blue fluorescence emissions are observed for 1 and 2 in the solid state at ambient temperature.     

Structures and Properties of Novel Mononuclear Iron(III) Complexes with Benzimidazole Containing Tripodal Tetradentate Ligands

The iron(III) complexes of the tripodal benzimidazole‐containing ligands tris(2‐benzimidazolylmethyl)amine (ntb), bis(2‐benzimidazolylmethyl)(2‐hydroxyethyl)‐amine (bbimae) and tris(5,6‐dimethyl‐2‐benzimidazolylmethyl)amine (me₂ntb) are structural and functional models for intradiol cleaving catechol dioxygenases. The complexes [Fe(ntb)Cl₂]Cl · 3 CH₃OH ( 1 ; P 1, a = 9.830(2) Å, b = 12.542(3) Å, c = 13.139(3) Å, α = 82.88(3)°, β = 73.45(3)°, γ = 85.53(3)°, V = 1539.2(6) ų; Z = 2) and [Fe(bbimae)Cl₂]Cl ( 2 ; P2₁/n, a = 7.461(2) Å, b = 18.994(5) Å, c = 14.515(4) Å, β = 98.22(2)°, V = 2035.8(9) ų, Z = 4) have been characterized by X‐ray crystallography and spectroscopic methods. In the octahedrally coordinated complexes two cis coordination sites – essential for catechol binding – are occupied by chloride ligands. The significant intradiol cleaving catechol dioxygenase activity of the model complexes was examined using 3,5‐di‐tert‐butylcatechol as a substrate.     

NMR of enaminones. Part 7 1H-, 13C-, and 17O-NMR and X-ray structure determinations of 1,2-disubstituted conjugated 3-[(tert-Butyl)amino]enones

¹H-, ¹³C-, and ¹⁷O-NMR spectra for the 2-substituted enaminones MeC(O)C(Me)?CHNH(t-Bu) ( 1 ), EtC(O)C(Me)?CHNH(t-Bu) ( 2 ), PhC(O)C(Me)?CHNH(t-Bu) ( 3 ), and MeC(O)C(Me)?CHNH(t-Bu) ( 4 ) are reported. These data show that 3 exists mainly in the (E)-form, 4 in (Z)-form, and 1 and 2 as mixtures of both forms. Polar solvents favour the (E)-form. The (Z)- and (E)-forms exist in the 1,2-syn,3,N-anti and 1,2-anti,1,N-anti conformations A and B , respectively. The structures of the (E)- and (Z)-form are confirmed by X-ray crystal-structure determinations of 3 and 4. The shielding of the carbonyl O-atom in the ¹⁷O-NMR spectrum by intramolecular H-bonding (Δλ_HB) ranging from ?28 to ?41 ppm, depends on the substituents at C(l) and C(2). Crystals of 3 at 90 K are monoclinic. with a = 9.618(2) Å, b = 15.792(3) Å, c = 16.705(3) Å, and β = 94.44(3)°, and the space group is P2₁/c with Z = 8 (refinement to R = 0.0701 on 3387 independent reflections). Crystals of 4 at 101 K are monoclinic, with a = 16.625(8) Å, b = 8.637(6) Å, c = 11.024(7) Å, and β = 101.60(5)°, and the space group is Cc with Z = 4 (refinement to R = 0.0595 on 2106 independent reflections).     

Synthesis and Structural Characterization of a Novel Indium Mercapto Derivative [ClIn(SCH2(CO)O)2]2-[(4-MepyH)2]2+

The synthesis and structural characterization of a novel In(III) complex is described. The reaction between InCl₃ with sodium mercapto-acetic acid (NaSCH₂(CO)OH) in 4-methylpyridine (CH₃(C₅H₅N), (4-Mepy)) at 25°C affords [ClIn(SCH₂(CO)O)₂]^2-[(4-MepyH)₂]²⁺ (1). X-ray diffraction studies of (1) show it to have a distorted square-pyramidal geometry with the [(^-SCH₂(CO)CO^-)] ligands in a trans conformation. The compound crystallizes in the P1(No. 2) space group with a = 7.8624(6) Å, b = 9.950(1) Å, c = 13.793(2) Å, α = 107.60(1)°, β = 90.336(8)°, γ = 98.983(9)°, V = 1014.3(4) ų, R(F°) = 0.037 and R_w = 0.048.     

THE CRYSTAL STRUCTURES OF TWO IMINO-1,2,4- DITHIAZOLES FORMED BY THERMAL DECOMPOSITION OF 5-(DIALKYLAMINO)-3-(SUBSTITUTED IMINO)-1,2,4-DITHIAZOLES

Abstract

The thermal decomposition products of two substituted imino-1,2,4-dithiazoles have been studied by single crystal x-ray analysis. Both products crystallize in space group P2^1/c with four molecules per unit cell. The first product, obtained from 5-(dimethylamino)-3-(methylimino)-1,2,4-dithiazole has cell dimensions of a=9.922(8) Å, b=12.052(11) Å, c=13.358(12) Å and β=104.9(1)°. The molecule is made up of two planar segments related by an extremely large twist (?154°) about a C?N double bond. The results from this study have also contributed further information in the area of nonbonded interactions between ring and thione sulfur atoms. The second product, from 5-(dimethylamino)-3(phenylimino)-1,2,4-dithiazole was shown to be an ordered 1:1 complex of the starting material and one of its isomers. The cell dimensions are a=12.420(6) Å, b=8.840(9) Å, c=22.276(22) Å and β= 112.2(1)°. The different molecules are linked by an inter molecular NH… N hydrogen bond.     

Crystal structure of 6-ferrocenyl-3-phenyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole

A new compound of 6-ferrocenyl-3-phenyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole is synthesized and its single crystal structure is determined by X-ray diffraction method. The compound belongs to the monoclinic P2₁/c space group with cell parameters: a = 10.5523(12) Å, b = 13.8414(16) Å, c = 11.4303(13) Å, V = 1603.5(3) ų.     

COPPER(I) COMPLEXES WITH N-(P-NITROPHENYL)-N′-ALKOXYCARBONYLTHIOUREA: SYNTHESES AND CRYSTAL STRUCTURES OF [Cu(H2net)2CI] · CH2CI2 AND [Cu(H2nmt)2CI]2·(CHCI3)2

Abstract

Two copper(I) complexes, [Cu(H₂net)₂Cl] · CH₂Cl₂ (1) and [Cu(H₂nmt)₂Cl]₂ · (CHCl₃)₂ (2), were synthesized by the reaction of CuCl₂ · 2H₂O with N-(p-nitrophenyl)-N′-(ethoxycarbonyl)-thiourea (H₂net) and N-(p-nitrophenyl)-N′-(methoxycarbonyl)-thiourea(H₂nmt), respectively. Both complexes crystallize in the monoclinic space group C2/c. For complex 1, a = 29.52(2), b=13.920(6), c = 14.873(3)Å; β= 101.75(2)°, V = 5984(4) ų, Z = 8 and R = 0.053; for complex 2, a = 30.68(1), b = 13.369(4), c = 14.226(7) Å, β = 99.52(4)°. V = 5754(4) ų, Z = 4 and R = 0.063. In complex 1, two H₂net molecules are bonded to Cu(I) atom through two S atoms forming a mononuclear complex with trigonal geometry for the Cu(I) ion [Cl(1)-Cu-S(1)=118.54(7), Cl(1)-Cu-S(2)=119.70(7), S(1)-Cu-S(2)=112.17(8)°, Cu-S(1) = 2.251(2), Cu-S(2) = 2.255(2), Cu-Cl(1) = 2.263(2) Å]. Complex 2 is a dimer formed by long Cu-S interactions [Cu-S* = 2.607(3) Å] from adjacent twc H₂nmt molecules; the Cu(I) ion has distorted tetrahedral coordination [Cl(1)-Cu-S(1) = 119.8(1), Cl(1)-Cu-S(2)=120.0(1), S(1)-Cu-S(2)=108.85(9)°] with unequal Cu-S [2.268(2), 2.247(2)Å] and Cu-Cl(1) [2.255(2)Å] bonds.     

Synthesis and Characterization of an Inorganic‐Organic Hybrid Layered Zinc Phosphite [(C2H3N3)Zn(HPO3)]

A inorganic‐organic hybrid zinc phosphite (C₂H₃N₃)Zn(HPO₃) ( 1 ) has been prepared under solvothermal conditions in the presence of 1,2,4‐triazole (trz) ligand.Its structure was determined by single‐crystal X‐ray diffraction, and further characterized by powder X‐ray diffraction (XRD), FTIR spectroscopy, elemental analysis, ICP analysis, thermogravimetric analysis and fluorescent spectrum. It crystallizes in the monoclinic system, space group P2₁/n, a = 7.5515(6) Å, b = 9.1813(8) Å, c = 10.0125(8) Å, β = 111.267(1)°, V = 646.92(9) ų, Z = 4. The structure consists of left‐handed and right‐handed helical chains that are connected through bridging oxygen atoms to form a two‐dimensional layer structure with 4.8‐net. The compound exhibits intense photoluminescence upon photo‐excitation at 326 nm.     

Synthesis,Crystal Structure,and Magnetic Properties of (2,2′‐dipyridylamine)(X−) Copper(II) Complexes (X−: Cyanate,Dicyanamide, Acetate,Thiocyanato)

The synthesis, structure, and magnetic properties of four 2,2′‐dipyridylamine ligand (abbreviated as Hdpa) containing copper(II) complexes. There is one binuclear compound, which is [Cu₂(μ_1,1‐NCO)₂(NCO)₂(Hdpa)₂] ( 1 ), and three mononuclear compounds, which are [Cu{N(CN)₂}₂(Hdpa)₂] ( 2 ), [Cu(CH₃CO₂)(Hdpa)₂·N(CN)₂] ( 3 ), and [Cu(NCS)(Acac)] ( 4 ). Compounds 1 and 4 crystallize in the monoclinic system, space group P2(1)/c and Z = 4, with a = 8.2465(6) Å, b = 9.3059(7) Å, c = 16.0817(12) Å, β = 91.090(1)°, and V = 1233.90(16) ų for 1 and a = 7.6766(6) Å, b = 21.888(3) Å, c = 10.4678(12) Å, β = 90.301(2)°, and V= 1758.8(4) ų for 4 . Compounds 2 and 3 crystallize in the triclinic system, space group P‐1 and Z = 1, with a = 8.1140(3) Å, b = 8.2470(3) Å, c = 9.3120(4) Å, β = 102.2370(10)°, and V = 592.63(4) ų for 2 and a = 7.4780(2) Å, b = 12.5700(3) Å, c = 13.0450(3) Å, β = 96.351(2)°, and V = 1211.17(5) ų for 3 . Complex ( 1 ), the magnetic data was fitted by the Bleaney‐Bowers equation (1). A very good fit was derived with J = 23.96, Θ = ?1.5 (g = 1.97). Complex ( 1 ) shows the ferromagnetism. Complexes ( 2 ), ( 3 ) and ( 4 ) of have the it is the typical paramagnetic behavior of unpaired electrons. Under a low temperature around 25 K, complexes ( 2 ) and ( 3 ) show weak ferromagnetic behavior. They are the cause of hydrogen bonds.     

Molecular Structure of RbSCN Complex with N-(4′-hydroxy-3′,5′-diisopropylbenzyl)-monoaza-15-crown-5 Ether: Two Structures in a Unit Cell

Abstract

Molecular structures of the RbSCN complexes with N-(4′-hydroxy-3′,5′-diisopropylbenzyl)-monoaza-15-crown-5 ether (2-RbSCN) and N-(4′-hydroxy-3′,5′-di-tert-butylbenzyl)-monoaza-15-crown-5 ether (3-RbSCN) are reported. Crystal data (2-RbSCN) C₂₄H₃₉N₂O₅SRb, M = 553.11, monoclinic, space group P2₁, a = 9.835(4), b = 15.44(3), c = 18.563(6) Å, β = 99.58 (4), U = 2779(4) ų, Z = 4, Dc = 1.322 gcm^?3, v = 18.87 cm^?1, R = 0.047, Rw = 0.049 for the 5339 independent reflections (of 5712 measured reflections) and 590 parameters. (3-RbSCN) C₅₂H₈₆N₄ O₁₀S₂Rb₂, M = 1162.32, triclinic, space group P2₁, a = 9.917(2), b = 24.644(6), c = 12.572(3), α = 89.38(2), γ = 96.13(2), γ = 89.34(2) Å, U = 3054(1) ų, Z = 2, Dc = 1.264 g cm^?3, μ = 17.20 cm^?1, R = 0.051, R = 0.053 for the 6864 independent reflections (of 7201 measured reflections) and 316 parameters. The molecular structures of the RbSCN complexes with a series of N-(4-hydroxy-3′,5′-dialkylbenzyl)-monoaza-15-crown-5 ethers (1, 2 and 3) were systematically changed depending upon the size of the R groups at positions 3′ and 5′ in the side arm; 1 (R=Me), a polymer-like (1:1)_n complex; 2 (R = i-Pr), a mixture of 1:1 complex and polymer-like (1:1)_n complex; 3 (R = t-Bu), a dimeric 1:1 complex.     

Structural studies of nickel(II) complexes with 1-<Emphasis Type="Italic">tert</Emphasis>-butylimidazole-2-thione and 3-phenyl-5-methyl-pyrazole ligands

The nickel(II) complexes dichlorobis(1-tert-butylimidazole-2-thione)nickel(II) [Ni(tm ^t-Bu)₂Cl₂] (1), dinitratobis(1-tert-butylimidazole-2-thione)nickel(II) [Ni(tm ^t-Bu)₂(NO₃)₂] (2), dichloro-bis(3-phenyl-5-methyl-pyrazole)(1-tert-butylimidazole-2-thione)nickel(II) [Ni(pz^Ph,MeH)₂(tm ^t-Bu)Cl₂] (3) and dinitratobis(3-phenyl-5-methyl-pyrazole)(1-tert-butylimidazole-2-thione)nickel(II) [Ni(pz^Ph,MeH)₂(tm ^t-Bu)(NO₃)₂] (4) have been synthesized and studied. The single crystal X-ray diffraction analysis was carried out for 1 and 4 {Bruker Kappa Apex-II CCD diffractometer, MoK _α radiation}. Crystal data for 1: monoclinic C2/c, a = 16.949(2) Å, b = 8.6647(10) Å, c = 15.461(3) Å, β = 117.662(4)°, V = 2011.1(5) ų, Z = 4, D _calc = 1.460 g/cm³. Crystal data for 4: triclinic P-1, a = 9.9775(7) Å, b = 11.2254(8) Å, c = 14.8068(10) Å, α = 75.401(4)°, β = 87.422(4)°, γ = 74.874(4)°, V = 1548.86(19) ų, Z = 2, D _calc = 1.405 g/cm³. Coordination core of complex 1 adopts distorted tetrahedral geometry whereas core 4 has distorted octahedral geometry. The bonded nitrates are of two types coordinating as monodentate and bidentate ligands.     

Transition Metal Halide Salts and Complexes of 2-Aminopyrimidine: Cobalt(II) and Nickel(II) compounds,Crystal Structures of Bis(2-Aminopyrimidinium)MX4 [M = Co,Ni; X = Cl,Br] and 2-Aminopyrimidinium(+2) [NiBr2(H2O)4]Br2

The reaction of MX₂ (M = Co(II), Ni(II); X = Cl, Br) with 2-aminopyrimidine in aqueous acid yields compounds [(2-apmH)₂MX₄], (2-apmH)₂[MX₄], or (2-apmH₂) [MX₂(H₂O)₄]X₂ (2-apmH = 2-aminopyrimidinium; 2-apmH₂ = 2-aminopyrimidinium(2+)). All compounds have been characterized by single crystal X-ray diffraction. The compounds [(2-apmH)₂MX₄] with M = Co, X = Cl (1); M = Ni, X = Cl (3); and M = Ni, X = Br (4) are isomorphous and crystallize as nearly square planar MX₄ units with the 2-apmH cations coordinated in the axial sites through the unprotonated ring nitrogen. (2-ApmH)₂[CoBr₄] (2) crystallizes as the salt with a nearly tetrahedral CuBr₄ ^2- anion. (2-ApmH₂)[NiBr₂(H₂O)₄]Br₂ (5) forms as a cocrystal of the neutral, six-coordinate nickel complex and (2-ampH₂)Br₂, stabilized by extensive hydrogen bonding. Crystal data (1): monoclinic, P2₁/c, a = 7.540(4), b = 12.954(4), c = 7.277(3) Å, β = 110.09(6), V = 667.4(5) ų, Z = 2, D_calc = 1.955 Mg/m³, μ = 2.079 mm^-1, R = 0.0501 for [|I|≥2(I)]. For (2): triclinic, P-1, a = 7.720(2), b = 7.916(2), c = 14.797(3) Å, α = 97.264(3), β = 104.788(3), γ = 105.171(3)°, V = 825.3(3) ų, Z = 2, D_calc = 2.296 Mg/m³, μ = 10.715 mm^-1, R = 0.0308 for [|I|≥2(I)]. For (3): monoclinic, P2₁/c, a = 7.595(3), b = 12.891(4), c = 7.204(3) Å, β = 111.07(3)°, V = 658.2 ų, Z = 2, D_calc = 1.982 Mg/m³, μ = 2.279 mm^-1, R = 0.0552 for [|I|≥2(I)]. For (4): monoclinic, P2₁/c, a = 7.840(2), b = 13.358(4), c = 7.518(2) Å, β = 110.923(3)°, V = 938.6(3) ų, Z = 2, D_calc = 2.577 Mg/m³, μ = 12.18 mm^-1, R = 0.0280 for [|I|≥2(I)]. For (5): orthorhombic, Pnma, a = 16.776(6), b = 11.943(4), c = 7.079(3) Å, V = 1418.2(9) ų, Z = 4, D_calc = 2.564 Mg/m³, μ = 12.639 mm^-1, R = 0.0381 for [|I|≥2σ(I)].     

Synthesis and X-ray study of 6<Emphasis Type="Italic">H</Emphasis>-chromeno[3,4-<Emphasis Type="Italic">e</Emphasis>][1,3,4]triazolo[2,3-<Emphasis Type="Italic">a</Emphasis>]pyrimidine

2-Dimethylamino methylenechromanone 1 reacted with 4H-1,2,4-triazol-3-amine in acetic acid to give only one isolated product which was identified by X-ray study as 6H-chromeno[3,4-e][1,3,4]triazolo[2,3-a]-pyrimidine. The molecular structure of 3, C₁₂H₈N₄O, was determined to be monoclinic, P2₁/c, a = 16.3875(5), b = 8.8378(3), c = 13.8392(5) Å, β = 101.190(1)°, V = 1966.22(11) ų, Z = 8.     

Alkoxo‐Verbindungen des dreiwertigen Eisen: Synthese und Charakterisierung von [Fe2(OtBu)6], [Fe2Cl2(OtBu)4], [Fe2Cl4(OtBu)2] und [N(nBu)4]2[Fe6OCl6(OMe)12]

Alkoxo Compounds of Iron(III): Syntheses and Characterization of [Fe₂(OtBu)₆], [Fe₂Cl₂(OtBu)₄], [Fe₂Cl₄(OtBu)₂] and [N(nBu)₄]₂[Fe₆OCl₆(OMe)₁₂] The reaction of iron(III)chloride in diethylether with sodium tert‐butylat yielded the homoleptic dimeric tert‐‐butoxide Fe₂(OtBu)₆ ( 1 ). The chloro‐derivatives [Fe₂Cl₂(OtBu)₄] ( 2 ), and [Fe₂Cl₄(OtBu)₂] ( 3 ) could be synthesized by ligand exchange between 1 and iron(III)chloride. Each of the molecules 1 , 2 , and 3 consists of two edge‐sharing tetrahedrons, with two tert‐butoxo‐groups as μ₂‐bridging ligands. For the synthesis of the alkoxides 1 , 2 , and 3 diethylether plays an important role. In the first step the dietherate of iron(III)chloride FeCl₃(OEt₂)₂ ( 4 ) is formed. The reaction of iron(III)chloride with tetrabutylammonium methoxide in methanol results in the formation of a tetrabutylammonium methoxo‐chloro‐oxo‐hexairon cluster [N(nBu)₄]₂[Fe₆OCl₆(OMe)₁₂] ( 5 ). Crystal structure data: 1 , triclinic, P1¯, a = 9.882(2) Å, b = 10.523(2) Å, c = 15.972(3) Å, α = 73.986(4)°, β = 88.713(4)°, γ = 87.145(4)°, V = 1594.4(5) ų, Z = 2, d_c = 1.146 gcm^—1, R₁ = 0.044; 2 , monoclinic, P2₁/n, a = 11.134(2) Å, b = 10.141(2) Å, c = 12.152(2) Å und β = 114.157(3)°, V = 1251.8(4) ų, Z = 2, d_c = 1.377 gcm^—1, R₁ = 0.0581; 3 , monoclinic, P2₁/n, a = 6.527(2) Å, b = 11.744(2) Å, c = 10.623(2), β = 96.644(3)°, V = 808.8(2) ų, Z = 2, d_c = 1.641 gcm^—1, R₁ = 0.0174; 4 , orthorhombic, Iba2, a = 23.266(5) Å, b = 9.541(2) Å, c = 12.867(3) Å, V = 2856(2) ų, Z = 8, d_c = 1.444 gcm^—1, R₁ = 0.0208; 5 , trigonal, P3₁, a = 13.945(2) Å, c = 30.011(6) Å, V = 5054(2) ų, Z = 6, d_c = 1.401 gcm^—1; R_c = 0.0494.