Transition-metal complexes with bidentate ligands spanning trans-positions. V. Crystal and molecular structures of complexes [RhCl(CO) (1)] and [PdCl2(1)]; 1 = 2,11-bis (diphenylphosphinomethyl)benzo [c]phenanthrene

The structures of [RhCl(CO) ( 1 )] and [PdCl₂ ( 1 )], where 1 is the bidentate ligand (C₆H₅)₂P·CH₂·C₁₈H₁₀· CH₂·P(C₆H₅)₂, have been determined from threedimensional X-ray counter data collected on single crystals of the C₆H₅·CN solvates. The two compounds are isomorphous and crystallize in the triclinic system, space group P 1 , Z = 2: a = 14.580 (8), b = 13.029 (10), c = 11.909 (6) Å, α = 106.33 (5), β = 100.47 (4), γ = 95.73 (5)° for the rhodium complex; a = 14.361 (5), b = 13.044 (7), c = 11.897 (4) Å, α = 105.97 (4), β = 100.27 (3), γ = 94.76 (4)°, for the palladium complex. In both complexes the metal atom is four-coordinate with slightly distorted square-planar configuration. In both cases the ligand 1 spans trans positions with M-P bond lengths in the ranges of the literature data. Also the other bond distances fall in regular ranges. Ligand 1 has almost the same conformation in both complexes and is characterized by a strong out-of-plane deformation of the benzophenanthrene system as a consequence of severe overcrowding.     

Über Pterinchemie. Mitteilung. Die Kristallstruktur von 5,6,7-Trimethyl-5,6,7,8-tetrahydropterindihydrochlorid-monohydrat

The crystal structure of 5,6,7-trimethyl-5,6,7,8-tetrahydropterine-dihydrochloride-monohydrate The crystal structure of the title compound has been determined by X-ray analysis (direct methods) and refined with 947 structure amplitudes to R = 0.026. The crystal system is orthorhombic, space group Pna2₁, with unit cell dimensions a = 14.081, b = 14.623, c = 6.773 Å. The molecule is protonated at the N(1)- and N(5)-position. The tetrahydropyrazine ring exists in a conformation in which C(6) deviates markedly from the mean plane of the other five atoms. The CH₃-groups at N(5) and C(6) possess a trans configuration with a pseudoaxial and an axial conformation respectively. The CH₃-groups at C(6) and C(7) in return possess the cis configuration, whereby the CH₃-group at C(7) occupies an equatorial conformation.     

Axial and Equatorial Substitution of Dimethylamine on Phosphorus in the 1,3,2-Oxazaphosphorinane Ring System: Structures of 2-Dimethylamino-Phenyl-2H-1,3,2-oxazaphosphorinane-2-Oxides

X-ray structures of trans-2-dimethylamino-5-phenyl-2H-1,3,2-oxazaphosphorinane-2-oxide, 5b , and trans-2-dimethylamino-6-phenyl-2H-1,3,2-oxazaphosphorinane-2-oxide, 6c , have been determined. These two compounds have been prepared in a straightforward manner by a reaction of cyclization of Mc₂NP(O)Cl₂ with the corresponding 3-amino-2-phenylpropanol and 3-amino-1-phenylpropanol, respectively, to produce (5b, 6b) and (5c, 6c) , and were separated into pure forms by chromatography. Crystal data of 5b : space group P_ccn, a = 10.675(5), b = 31.685(9), c = 7.217(3) Å, R = 0.065 for 1040 reflections. Crystal data of 6c: space group P-1, a = 9.803(6), b = 12.455(5), c = 12.690(2) Å, α = 114.11(2), β = 80.88(2), γ = 111.64(4)°, R = 0.035 for 3534 reflections. For the pair 5b and 6b , the slowly-migrating 5b is trans (Ph and P = O group trans) with the configuration of 2RS, 5RS, hence 6b is the cis isomer. For the pair 5c and 6c , the slowly migrating 6c is trans with the configuration of 2RS, 6SR; hence 5c is the cis isomer. In both X-ray structures the 1,3,2-oxazaphosphorinane rings are chair-like with the P-end essentially flattened. With a conformationally demanding 5-phenyl substituent, 5b has an axial Me₂N whereas with also a conformationally demanding 6-phenyl substituent, 6c has an equatorial Me₂N. For 6c , the exocyclic P-N bond has partial double bond character: the geometry about exocyclic N is planar. On the other hand, for 5b , the geometry about exocyclic N deviates considerably from planarity, the sum of the angles around N being 343.3°. In the crystalline state, the two crystallographically independent molecules of 6c are linked together in a hydrogen-bonded system involving the water molecule.     

Über Pterinchemie. 90. Mitteilung. Synthese und Kristallstruktur des ersten chinoiden Dihydropterinmolybdän (IV)-Komplexes

Synthesis and Crystal Structure of the First Quinoid Dihydropterinmolybdenum (IV) Complex The first molybdenum(IV) complex with a quinoid dihydropterin, i.e. 2 , was isolated and characterized by IR, UV and NMR data and single-crystal X-ray diffraction. The reaction of Mo^VIO₂Cl₂ with the biologically important 6β-5,6,7,8-tetrahydro-L-biopterin(²) ( 7 ) in MeOH gave almost quantitatively trichloro(1,5-quinoid-7,8-dihydro-6H-L-biopterin)oxomolybdenLim(IV) ( 2 ). The complex crystallizes with one molecule of MeOH in the noncentrosymmetric orthorhombic space group P2₁2₁2₁ (No. 19) with unit cell dimensions a = 1009.3(3), b = 1104.7(3), and c = 1484.5(4) pm and Z = 4. The Mo-atom has a distorted octahedral geometry (Fig.1). It is coordinated by N(5) and O(4) of the pterin ligand. The distance of the Mo–N(5) bond (202 pm) is unusually short compared to similar complexes. O(4) is located trans to a terminal oxo ligand. The octahedral coordination is completed by three Cl-atoms in a meridional arrangement. Complex 2, with the Mo-atom in the enzyme-relevant oxidation state +IV and the pterin in the intermediate quinoid dihydro form, should lead to an extension of the proposed ‘common molybdenum cofactor’ model.     

Synthesis of 2H-indazole-4,7-dione derivatives from 3-phenylsydnone and p-toluquinone. The crystal and molecular structure of 6-bromo-5-methyl-2-phenyl-2H-indazole-4,7-dione

The 1,3-dipolar cycloaddition of 3-phenylsydnone with p-toluquinone afforded 5-methyl- and 6-methyl-2-phenyl-2H-indazole-4,7-diones 3a and 3b. No regioselectivity was observed in this cycloaddition yielding an equimolar amount of the regioisomers. Reactions of 3a and 3b with bromine gave the corresponding mono- 4a and 4b and dibromo derivatives 5a and 5b , respectively. The crystal structure of 6-bromo-5-methyl-2-phenyl-2H-indazole-4,7-dione ( 4a ) has been determined by the single crystal X-ray method. The crystals are monoclinic, space group PI with two molecules in a unit cell of dimensions a = 8.029(1), b = 14.309(1), c = 5.895(1)Å, β = 90.24(1)° and V = 621 ų. The structure has been solved by the direct method using 1827 reflections and refined by full-matrix least-squares calculations to R = 0.0739.     

Carotinoide mit 7-Oxabicyclo[2.2.1]heptyl-Endgruppen. Teil I. Versuch einer Synthese von Cycloviolaxanthin (= (3S,5R,6R,3′S,5′R,6′R)-3,6:3′,6′-Diepoxy-5,6,5′,6′-tetrahydro-β,β-carotin-5,5′-diol)

Carotenoids with 7-Oxabicyclo[2,2.1]heptyl End Groups. Attempted Synthesis of Cycloviolaxanthin ( = (3S,5R,6S,3′S,5′R,6′R)-3,6:3′,6′- Diepoxy-5,6,5′,6′-tetrahydro-β,β-carotin-5,5′-diol) Starting from our recently described synthon (+)- 24 , the enantiomerically pure 3,6:4,5:3′,6′:4′,5′-tetraepoxy-4,5,4′,5′-tetrahydro-ε,ε-carotene ( 34 ) and its 15,15′-didehydro analogue 32 were synthesized in eleven and nine steps, respectively (Scheme 4). Chiroptical data show, in contrast to the parent ε,ε-carotene, a very weak interaction between the chiral centers at C(5), C(5′), C(6), C(6′), and the polyene system. Diisobutylaluminium hydride reduction of 32 lead rather than to the expected 15,15′-didehydro analogue 35 of Cycloviolaxanthin ( 8 ), to the polyenyne 36 (Scheme 5). We explain this reaction by an oxirane rearrangement leading to a cyclopropyl ether followed by a fragmentation to an aldehyd on the one side and an enol ether on the other (Scheme 6). This complex rearrangement includes a shift of the whole polyenyne chain from C(6), C(6′) to C(5), C(5′) of the original molecule.     

Reaction of hexanuclear niobium and tantalum halide clusters with mercury(II) halides. II. Semiconducting compounds with [Ta6Cl12] unit

A series of paramagnetic clusters of the composition [(Ta₆Cl₁₂)Cl(H₂O)₅][HgX₄] · 9H₂)O (X = Cl, Br, I) has been prepared by the reaction of [Ta₆Cl₁₂]³⁺ methanol-water solutions with HgX₂ and NaX halides. The structure of [(Ta₆Cl₁₂)Cl(H₂O)₅][HgBr₄] · 9H₂O has been solved by X-ray diffraction in the cubic space group Fd 3m. Crystal data: a = 20.036(2) Å, V = 8043.0(1) ų, Z = 8, R = 0.048 (R_w = 0.051). The structure is composed of an octahedral [(Ta₆Cl₁₂)Cl(H₂O)₅]²⁺ cluster cation, tetrahedral [HgBr₄]²⁻ anion and crystal water molecules. The 2mm symmetry of the octahedron is reduced by the statistical distribution of the five water molecules, O(1), and chlorine, Cl(2), at the terminal coordination sites. Thus, the distances Ta-O(1) and Ta-Cl(2) are averaged to the value of 2.32(2) Å. The Ta-Ta and Ta-Cl(1) bond distances are 2.911(1) Å and 2.440(3) Å, respectively, whereas the Hg-Br bond distance is 2.564(3) Å. The cluster [(Ta₆Cl₁₂)Cl(H₂O)₅][HgBr₄] · 9H₂O is semiconducting with two levels governing conductivity with respective activation energies, E_al = 0.24 eV and E_a2 = 0.17 eV.     

Polyol—Metall-Komplexe. III. Lithium-bis(oxolandiolato)cuprat-Tetrahydrat und Lithium-μ-propantriolato-cuprat-Hexahydrat — zwei homoleptische Kupfer(II)-Komplexe mit Polyolat-Liganden aus den mehrfach deprotonierten Polyolen Anhydro-erythrit und Glycerol

Polyol Metal Complexes. III. Lithium Bis(oxolanediolato)cuprate Tetrahydrate and Lithium μ-Propanetriolatocuprate Hexahydrate — Two Homoleptic Copper(II) Complexes with Polyolate Ligands Derived from the Multiply Deprotonated Polyols Anhydro-erythritol and Glycerol . In the blue-violet crystals of lithium bis{meso-oxolane-3, 4-diolato(2 - )}cuprate tetrahydrate, Li₂[Cu(C₄H₆O₃)₂] · 4H₂O ( 1 ) (P2₁/c, a = 706.2(4), b = 1114.0(6), c = 958.3(5) pm, β = 107.67(3)°, Z = 2, R_w = 0.022), square-planar coordinated copper(II) ions are bound to twofold deprotonated anhydro-erythrol ligands (Cu? O 194.36(17) and 191.83(17) pm). The oxygen ligator atoms of the mononuclear cuprate ions are bound to lithium ions or they are acceptors in asymmetrical hydrogen bonds. Trinuclear tris-{μ-propanetriolato(3 - )}tricuprate ions with triply deprotonated glycerol as ligands are present in the deep blue columns of LiCuC₃H₅O₃ · 6H₂O ( 2 ) (P3 c1, a = 1 278.8(6), c = 2 420.5(12) pm, Z = 12, R_w = 0.059), which has been prepared for the first time by Bullnheimer [2]. The copper(II) ions in 2 are also bound to alkoxide oxygen atoms in square-planar coordination (Cu? O 190.7(7) and 192.4(8), Cu? μ-O 196.6(6) and 195.0(7) pm). The hydrogen bond system and the content of channels parallel [001] are described in terms of a disorder model.     

Kristallstrukturen von Säurehydraten und Oxoniumsalzen. 36 [1]. Selensäure-Tetrahydrat. Ionisch gemäß (H5O2)2SeO4 in einer orthorhombischen sowie einer tetragonalen Form

Crystal Structures of Acid Hydrates and Oxonium Salts. 36 [1]. Selenic Acid Tetrahydrate. Ionic as (H₅O₂)₂SeO₄ in an Orthorhombic as well as a Tetragonal Form Low-melting selenic acid tetrahydrate has been studied for the first time by crystal structure analysis. Two forms have been observed, an orthorhombic one with space group Pnma and Z = 4 and a tetragonal one with space group P4 2₁c and Z = 2. The lattice parameters at ?150°C are a = 6.130(3), b = 12.776(6) and c = 9.299(5) Å for the orthorhombic and a = 7.676(4) and c = 6.378(3) Å for the tetragonal form. Both forms are oxonium salts, corresponding to (H₅O₂)₂SeO₄. The ions are hydrogen-bonded into a three-dimensional array. The bonds within the diaquahydrogen cations have O ?O distances of 2.422(5) and 2.425(4) Å. The tetragonal form is isotypic to the tetrahydrate of sulfuric acid.     

Contracted Gaussian-type basis functions revisited. IV. Atoms Rb to Xe

We report minimal-type contracted Gaussian-type function (GTF) sets, #n=(n3333/n33/n3) with n=5 and 6, #7= (74333/743/74), and #8= (84333/843/75), for the fourth-row atoms from Rb to Xe. Test calculations are performed on the Ag₂ molecule. Spectroscopic constants given by split valence sets derived from #5 and #6 are a little contaminated by basis set superposition error. However, we find that the fully valence split #8 set, (8433111/84111/711111), yields essentially the same results as a large GTF set, (22s15p12d), with a general contraction, when p-, d-, and f-type polarization functions are augmented. The present #7 and #8 CGTF sets are recommended for ab initio molecular calculations including fourth-row atoms. Received: 15 January 2002 / Accepted: 16 April 2002 / Published online: 24 June 2002     

Reaction of Early Transition Metal Complexes With Macrocycles III. Synthesis and Structure of 18-Crown-6·l4 (M = Ti,Sn)

Abstract

18-Crown-6 reacts with either TiCl₄ or SnCl₄ in toluene to form an addition complex in which the macrocycle functions as a bidentate ligand. The two compounds are isostructural and belong to the monoclinic space group P2₁/n. For Ti. the cell parameters are a = 10.501(6), b = 18.104(5), c = 10.955(5) Å, β = 109.76(3)°, and D_c = 1.55 g/cm³ for Z = 4; for Sn, a = 10.572(9), b = 18.139(6), c = 11.056(5) Å, β = 109.16(4)°, and D_c = 1.75 g/cm³. Least-squares refinement led to a final R = 0.037 for 1735 observed reflections for the Ti complex, and R = 0.038 for 2940 observed reflections for the Sn derivative. The M-Cl lengths range from 2.221(2)–2.285(2) Å for M = Ti, and from 2.353(2)–2.357(2) Å for M = Sn. The M—O bonds are 2.102(4) and 2.138(4) Å for M = Ti, and 2.212(4) and 2.237(4) Å for M = Sn.     

Homologous Silver Bismuth Chalcogenide Halides (N,x)P. II. The (2, x)P and (3, x)P Structure Families of Modular Compounds with Tunable Composition and Structure

The crystal structures of two members of the solid solution series Ag_3xBi_5?3xS_8?6xCl_6x?1 (x = 0.52 (I) , x = 0.67 (II) ) and three compounds of the Ag_4xBi_6?4xQ_10?8xBr_8x?2 series (Q = S: x = 0.70 (III) , x = 0.84 (IV) ; Q = Se: x = 0.72 (V) ) were determined by single‐crystal X‐ray diffraction. The compounds crystallize in the monoclinic space group C2/m (No. 12) with a = 1326.7(3), b = 403.9(1), c = 1176.7(2) pm, β = 107.83(3)° for (I) ; a = 1325.4(3), b = 403.3(1), c = 1170.6(2) pm, β = 108.14(3)° for (II) ; a = 1338.9(4), b = 407.7(1), c = 1426.4(4) pm, β = 113.95(2)° for (III) ; a = 1346.7(4), b = 409.3(1), c = 1440.7(4) pm, β = 114.40(1)° for (IV) ; and a = 1370.9(2), b = 417.64(4), c = 1480.4(2) pm, β = 114.92(2)° for (V) . (I) and (II) adopt the PbBi₄S₇ structure type, (III) to (V) crystallize in the CuBi₅S₈ type. All five compounds belong to the homologous series with general formula [BiQX]₂[Ag_xBi_1?xQ_2?2xX_2x?1]_N+1 (Q = S, Se; X = Cl, Br; 1/2 ≤ x ≤ 1)), which resemble minerals of the pavonite series. They are characterized by the parameters N and x and are denoted ^{(N, x)}P. In the crystal structures, two kinds of layered modules alternate along [001]. Modules of type A uniformly consist of paired rods of face‐sharing monocapped trigonal prisms around Bi atoms with octahedra around mixed occupied metal positions (M = Ag/Bi) between them. Modules of type B are composed of chains of edge‐sharing [MZ₆] octahedra (M = Ag/Bi; Z = Q/X). These NaCl‐type fragments are of thickness N = 2 in Ag_3xBi_5?3xS_8?6xCl_6x?1 and N = 3 in Ag_4xBi_6?4xQ_10?8xBr_8x?2. All structures exhibit Ag/Bi disorder in octahedrally coordinated metal positions and Q/X mixed occupation of some anion positions.     

Front Cover: Non-conventional Behavior of a 2,1-Benzazaphosphole: Heterodiene or Hidden Phosphinidene? (Chem. Eur. J. 52/2021)

The titled 2,1-benzazaphosphole ( 1 ) (i. e. ArP, where Ar=2-(DippN=CH)C₆H₄, Dipp=2,6-iPr₂C₆H₃) showed a spectacular reactivity behaving both as a reactive heterodiene in hetero-Diels-Alder (DA) reactions or as a hidden phosphinidene in the coordination toward selected transition metals (TMs). Thus, 1 reacts with electron-deficient alkynes RC≡CR (R=CO₂Me, C₅F₄N) giving 1-phospha-1,4-dihydro-iminonaphthalenes 2 and 3 , that undergo hydrogen migration producing 1-phosphanaphthalenes 4 and 5 . Compound 1 is also able to activate the C=C double bond in selected N-alkyl/aryl-maleimides RN(C(O)CH)₂ (R=Me, tBu, Ph) resulting in the addition products 7–9 with bridged bicyclic [2.2.1] structures. The binding of the maleimides to 1 is semi-reversible upon heating. By contrast, when 1 was treated with selected TM complexes, it serves as a 4e donor bridging two TMs thus producing complexes [μ-ArP(AuCl)₂] ( 10 ), [(μ-ArP)₄Ag₄][X]₄ (X=BF₄ ( 11 ), OTf ( 12 )) and [μ-ArP(Co₂(CO)₆)] ( 13 ). The structure and electron distribution of the starting material 1 as well as of other compounds were also studied from the theoretical point of view.     

Die diastereomeren Mutatochrome. Trennung,absolute Konfiguration sowie chiroptische,spektroskopische und chromatographische Charakterisierung

Diastereoisomeric Mutatochromes: Separation, Absolute Configuration, and Spectra and Chromatographic Behaviour (5S, 6R)-5, 6-Epoxy-5, 6-dihydro-β, β-carotent ( 2 ), prepared from azafrinal ( 1 ) was rearranged in an acid-catalyzed reaction into the mixture of (5S, 8S)- and (5S, 8 R)-5, 8-epox-5, 8-dihydro-β, β-carotenes = ‘mutatochrome’. HPLC separation of the individual diastereoisomers led to the pure isomers for the first time. Their structures were assigned by analysis of the characteristic pattern of the signals of H? C(7) and H? C(8), respectively, in ¹H-NMR spectra. Although many reports of the occurrence of ‘mutatochrome’ exist, it is as yet not clear whether optically active or racemic forms predominate in nature. Combination of HPLC separations with UV/VIS and CD spectra should now allow an unambigous identification of the isomer in question.     

Cluster chemistry. 61. Addition of HX (XCl,Br,I) or AuCl(PPh3) to an open Ru5 cluster. X-ray structures of Ru5(μ-H)(μ5-C2PPh2)(μ-PPh2)(μ-Br)(CO)13 and Ru5(μ-H)(μ5-C2PPh2)(μ3-I)(μ-PPh2)(CO)12

Reactions of aqueous HX (X?Cl, Br) or of AuCl(PPh₃) with Ru₅(μ₅-C₂PPh₂)(μ-PPh₂)(CO)₁₃ result in addition of the 4e-donor set (H + X) or (Au(PPh₃) + Cl) with concomitant opening of two Ru? Ru bonds to give complexes containing dimetallated triangular of ‘scorpion’ cores. Aqueous HI reacts similarly, but in this case the iodide ligand spans three Ru atoms, the (H + I) set acting as 6e-donor. The structures of the two title compounds were confirmed by X-ray crystallographic studies. Ru₅(μ-H)(μ₅-C₂PPh₂)(μ-PPh₂)-(μ-Br)(CO)₁₃ is triclinic, space group P1 , a = 9.689(2), b = 11.874(2), c = 20.005(4) Å, α = 84.66(2), β = 82.90(6), λ = 67.51(6)°, Z = 2; 6478 data with I > 2σ(I) were refined to R = 0.0368, R_w = 0.0362. Ru₅(μ-H)(μ₅-C₂PPh₂)(μ₃-I)(μ-PPh₂)-(CO)₁₂.CH₂Cl₂ is monoclinic, space group P2₁/n, a = 14.809(4), b = 20.721(4), c = 17.698(5) Å, β = 111.42(2)°, Z = 4; 7815 data with I > 2σ(I) were refined to R = 0.0440, R_w = 0.0416.     

A Novel Alkene(alkyl)(aqua)(aryl)platinum(II) Complex – [Pt{CH(CH2C6F5)CH2CH2CH=CH2}(C6F5)(OH2)]

From the reaction of PtCl₂(hex) (hex = hexa‐1,5‐diene) with LiC₆F₅ in diethyl ether, the complex [Pt{CH(CH₂C₆F₅)CH₂CH₂CH=CH₂}(C₆F₅)(OH₂)] ( 1 ) was isolated. The crystal structure (monoclinic, C2/c (no. 15), Z = 8, a = 15.241(3), b = 16.579(2), c = 16.225(2) Å, β = 111.12(2)°) shows a complex with square planar coordination around platinum with a template formed 1‐pentafluorophenylhex‐5‐en‐2‐yl ligand, and C₆F₅ and aqua ligands trans to the double bond and alkyl carbon, respectively.     

Photochemische Reaktionen. 112. Mitteilung [1] Zur Photochemie α, β-ungesättigter γ, δ-Epoxyester. III. Ergänzende Untersuchungen zur Triplettreaktivität

On triplet sensitization (E)- 5 gives (Z)- 5 and isomerizes via C(δ), O-bond cleavage to the cyclobutanone 6 and the conjugated γ-ketoester 7 . - On singulet excitation 6 undergoes decarbonylation and yields the bicyclo [4.1.0]heptane 8 . However, on triplet sensitization 6 is converted to the isomeric tricyclononane 9 by a stereospecific oxa-di-π-methane rearrangement. The structure of 9 is determined by X-ray analysis of the p-nitrobenzoate 15: a = 10.573, b = 14.707, c = 13.494 Å, β = 112.40°, P2₁/n, Z, = 4.     

Crystal Structures of Two Monomeric Copper(II) Carboxylates with 2-Aminopyridine

The crystal structures of two monomeric copper(II) carboxylates with 2-aminopyridine have been determined by X-ray diffraction. The hexanoate complex crystallizes as its acetonitrile solvate [Cu(C₆H₁₁O₂)₂(C₅H₆N₂)₂ · CH₃CN] in the triclinic space group P-1 with a = 8.1020(6), b = 13.7106(9), c = 13.7673(9) Å, = 113.79(1), = 103.86(1), and = 94.38(4). The heptanoate compound shows an unsolvated structure [Cu(C₇H₁₃O₂)₂(C₅H₆N₂)₂] and also crystallizes in the triclinic space group P-1 with the following cell parameters: a = 8.4487(9), b = 12.238(1), c = 13.504(2) Å, = 87.034(9), = 77.489(9), and = 71.41(1)^°. Both compounds contain the CuO₄N₂ chromophore, with ligands arranged around the copper center in a cis mode. 2-Aminopyridine is coordinated through the endocyclic nitrogen atom. The ortho position of the amino group, with respect to the pyridine nitrogen atom, allows the formation of both, intra-and intermolecular hydrogen bonds.     

Neue ternäre Germanide: Die Verbindungen Ln4Zn5Ge6 (Ln: Gd,Tm, Lu)

New Ternary Germanides: The Compounds Ln ₄Zn₅Ge₆ ( Ln : Gd, Tm, Lu) Three new ternary germanides were prepared by heating mixtures of the elements. Gd₄Zn₅Ge₆ (a = 4.249(3), b = 18.663(17), c = 15.423(6) Å), Tm₄Zn₅Ge₆ (a = 4.190(1), b = 18.410(5), c = 15.105(5) Å), and Lu₄Zn₅Ge₆ (a = 4.179(1), b = 18.368(4), c = 15.050(3) Å) are isotypic and crystallize in a new structure type (Cmc2₁; Z = 4), composed of edge‐ and corner‐sharing ZnGe₄ tetrahedra. The rare‐earth atoms fill channels of the Zn,Ge network running along the a axis and predominantly have an octahedral coordination of Ge atoms or a pentagonal prismatic environment of Zn and Ge atoms. The ZnGe₄ tetrahedra are orientated to each other so that two of six Ge atoms form pairs, while the other ones have no homonuclear contacts. This is in accord with an ionic splitting of the formula: (Ln³⁺)₄(Zn²⁺)₅(Ge^3–)₂(Ge^4–)₄. LMTO band structure calculations support the interpretation of bondings derived from interatomic distances. The metallic conductivity of these compounds expected from the electronic band structure was confirmed by measurements of the electrical resistance of Tm₄Zn₅Ge₆.     

Conformational Studies of Dibenzo-30-crown-10 Complexes. Syntheses and Crystal Structures of Potassium and Ammonium Hexafluorophosphate Complexes

Abstract

Crown ether complexes formed by the dibenzo–30-crown–10 (DB30C10) with potassium and ammonium hexafluorophosphate have been prepared and their crystal structures have been determined by single crystal X-ray analyses. The potassium complex (compound 1) consists of [K(DB30C10)]⁺ cation and PF₆ ^? anion. Crystals are monoclinic, space group P2/n, with a = 11.9106(3), b = 9.8382(5), c = 14.3062(3) Å, β = 97.581(3)°, V = 1661.7(1) ų, D_c = 1.440 g cm^?3, Z = 4, R = 0.0675 for 2528 unique observed reflections. The potassium atom is coordinated to the ten oxygen atoms of the crown ligand at the distance from 2.859(3) to 2.930(3) Å. The ammonium complex (compound 2) has also 1:1 crown—cation ratio. Crystals are monoclinic, space group P2₁/n, with a = 12.5061(6), b = 19.3724(5), c = 14.2203(9) Å, β = 102.476(5)°, V = 3363.8(3) ų, D_c = 1.501 g cm^?3, Z = 4, R = 0.0677 for 4172 unique observed reflections. The ammonium cation is completely enclosed with crown oxygen atoms forming seven hydrogen bonds. The conformation of previously reported dibenzo-30-crown-10 complexes with potassium salts were investigated using polar coordinate maps.