Neue Polyiodide des Caesiums mit Doppel‐ und Tripeldecker‐Kationen, [Cs(Benzo‐18‐Krone‐6)2]Ix und [Cs2(Benzo‐18‐Krone‐6)3](Ix)2 (x = 3, 5)

New Polyiodides of Cesium containing Double and Triple Decker Cations, [Cs(benzo‐18‐crown‐6)₂]I_x and [Cs₂(benzo‐18‐crown‐6)₃](I_x)₂ (x = 3, 5) [Cs(b18c6)₂]I_x (x = 3 (1) , 5 (3) ) and [Cs₂(b18c6)₃](I_x)₂ (x = 3 (2) , 5 (4) ) (b18c6 = benzo‐18‐crown‐6) have been synthesized by the reaction of benzo‐18‐crown‐6 (C₁₆H₂₄O₆), cesium iodide (CsI) and iodine (I₂) in acetonitrile ( 1 ), ethanol/dichloromethane ( 2 , 4 ) and 2‐methoxyethanol ( 3 ). Their crystal structures were determined on the basis of single crystal X‐ray data {( 1 ): monoclinic, C2/c, Z = 4, a = 2048.8(5), b = 1329.5(5), c = 1588.7(5) pm, β = 110.23(1)°; ( 2 ): monoclinic, C2/c, Z = 4, a = 2296.0(1), b = 2092.7(1), c = 1373.6(1) pm, β = 100.21(1)°; ( 3 ): monoclinic, P2₁/n, Z = 4, a = 1586.3(1), b = 1745.5(1), c = 1608.6(1) pm, β = 92.37(1)°; ( 4 ): triclinic, , Z = 2, a = 1241.7(1), b = 1539.8(2), c = 1938.4(2) pm, α = 91.15(1), β = 100.53(1), γ = 95.26(1)°}. As expected, double decker cations centered by Cs atoms, [Cs(b18c6)₂]⁺, are found in the structures of ( 1 ) and ( 3 ). In contrast, the triple decker cation found in ( 2 ) and ( 4 ) is less common. The triiodide anions of ( 1 ) and ( 2 ) can be regarded as normal and the chain‐type pentaiodide anions of ( 3 ) and ( 4 ) fall into the known systematic sequence of these anions. The differences in the connectivity of the crystallographically independent I₅^? anions in ( 4 ) are surprising with respect to the fact that, so far, independent pentaiodide anions do not show variations in their scheme of connectivity within one crystal structure.     

Pentaiodide komplexer Alkalimetall‐Kronenether‐Kationen: Darstellung und strukturelle Charakterisierung der Verbindungen [M(Benzo‐15‐Krone‐5)2]I5 mit M = Na,K, Rb,Cs

Pentaiodides of Complex Alkaline Metal Crown Ether Cations: Synthesis and Structural Characterisation of the Compounds [M(benzo‐15‐crown‐5)₂]I₅, M = Na, K, Rb and Cs The isotypic compounds [M(benzo‐15‐crown‐5)₂]I₅, M = Na, K, Rb and Cs are obtained as single crystals via the reaction of benzo‐15‐crown‐5, MI and iodine (2 : 1 : 2) from ethanol/dichloromethane (1 : 1). These compounds crystallize in the monoclinic space group P2₁/n with four formula units in the unit cell. The cations form typical sandwich complexes. The volume of the unit cell increases by 4, 3 % from the sodium to the caesium compound, corresponding to the increasing space required by the cations. The pentaiodide units consist of a elongated triiodide unit and two iodine half‐molecules. These iodine molecules are completed by centres of symmetry. The interconnection between the pentaiodide units leads to the formation of zig‐zag chains that run along [001]. Considering the strongly different ionic radii of the alkali‐metal cations, the existence of this number of isotypic structures is rather surprising.     

Isolated pentaiodide anions in [K(18‐crown‐6)]I5

(1,4,7,10,13,16‐Hexaoxa­cyclo­octa­decane‐κ⁶O)­potassium penta­iodide, [K(C₁₂H₂₄O₆)]I₅, obtained by slow evaporation of an ethanol solution of KI, 18‐crown‐6 and I₂, contains [K(18‐crown‐6)]⁺ cations (C_i symmetry) and I₅⁻ anions (C₂ symmetry), which are arranged in alternating layers parallel to (001). In contrast to the well known tendency of I₅⁻ ions to form chains and nets, the I₅⁻ units in the title compound are isolated.     

Komplexe einwertiger Dibenzo‐18‐Krone‐6‐Kationen mit Triiodid als Anionen

Complexes of Monovalent Dibenzo‐18‐crown‐6 Cations with Triiodide as Anions The new polyiodides [NH₄(db18c6)]₂(I₃)₂ ( 1 ), [NH₄(db18c6)](db18c6)I₃ ( 2 ), [Na_1/2(db18c6)H₂O]₂I₃ ( 3 ), [Rb(db18c6)]I₃ ( 4 ), [Rb(db18c6)]₂(I₃)₂ ( 5 ), [Cs(db18c6)]I₃ ( 6 ), and [Cs₂(db18c6)₃][Cs(db18c6)_3/2](I₃)₃ ( 7 ) were obtained from reactions of dibenzo‐18‐crown‐6 (db18c6) and iodine with NH₄I, NaI, RbI, and CsI. Their crystal structures were determined by single‐crystal X‐ray diffraction. ( 1 ) M = NH₄, ( 5 ) M = Rb: monoclinic, P2₁/n, a = 1409,67(8), b = 2211,63(14), c = 1627,16(10) pm, β = 101,030(5)°, Z = 4 (crystal data for M = NH₄); ( 2 ): monoclinic, Pn, a = 1345,26(14), b = 773,82(4), c = 2095,10(20) pm, β = 94,439(8)°, Z = 2; ( 3 ): orthorhombic, Pnaa, a = 931,59(13), b = 2213,3(5), c = 2223,9(4) pm, Z = 4; ( 4 ): monoclinic, P2₁/n, a = 999,50(6), b = 1711,33(10), c = 1517,45(9) pm, β = 99,021(5)°, Z = 4; ( 6 ): triclinic, , a = 705,16(9), b = 1137,93(14), c = 1678,90(20) pm, α = 73,719(10), β = 79,782(10), γ = 83,669(10)°, Z = 2; ( 7 ): triclinic, , a = 1519,25(6), b = 1702,49(7), c = 2136,41(9) pm, α = 102,641(3), β = 101,989(3), γ = 91,911(3)°, Z = 2. 1 : 1 cations centered by M, [M(db18c6)]⁺, are found in the structures of ( 1 – 6 ). In contrast, the triple decker cation found in ( 7 ) is less common. The crystal structures are completed by mostly asymmetrically linear I₃^? anions.     

Pb(18‐crown‐6)Cl2 and Hg(18‐crown‐6)I2: Molecular Dihalides Trapped in a Crown Ether

Pb(18‐crown‐6)Cl₂ and Hg(18‐crown‐6)I₂ are obtained as transparent colourless crystals of needle and hexagonal shape, respectively, by isothermal evaporation of their dichloromethane solutions. Pb(18‐crown‐6)Cl₂ crystallizes with the trigonal crystal system [ , no. 148, a = b = 1176.3(2), c = 1191.8(3) pm, V = 1428.2(5) 10⁶·pm³, Z = 3] whereas Hg(18‐crown‐6)I₂ crystallizes with the orthorhombic crystal system (Pnma, no. 62, a = 1613.9(2) pm, b = 2822.2(5) pm, c = 841.3(1) pm, V = 3832(1)10⁶·pm³, Z = 8). Both compounds are characterized by linear MX₂ (HgI₂ or PbCl₂) molecular units which are encrypted by the crown ether. In both cases, the divalent metal ion resides in the middle of the crown ether resulting in a hexagonal bipyramidal coordination environment for the metal cations. The molecular symmetry comes close to D_3d. Hg(18‐crown‐6)I₂ and Pb(18‐crown‐6)Cl₂ differ in the way the single MX₂@18‐crown‐6 units are packed. Whereas the Hg(18‐crown‐6)I₂ molecules are arranged in a (distorted) cubic closest packing, the Pb(18‐crown‐6)Cl₂ molecules adopt a hexagonal closest packing.     

Quecksilber(II)‐chlorid‐ und ‐iodid‐Komplexe von Dithia‐ und Tetrathiakronenethern

Mercury(II) Chloride and Iodide Complexes of Dithia‐ and Tetrathiacrown Ethers The complexes [(HgCl₂)₂((ch)₂30S₄O₆)] ( 1 ), [HgCl₂(mn21S₂O₅)] ( 2 ), [HgCl₂(ch18S₂O₄)] ( 3 ) and [HgI(meb12S₂O₂)]₂[Hg₂I₆] ( 4 ) have been synthesized, characterized and their crystal structures were determined. In [(HgCl₂)₂((ch)₂30S₄O₆)] two HgCl₂ units are discretely bonded within the ligand cavity of the 30‐membered dichinoxaline‐tetrathia‐30‐crown‐10 ((ch)₂30S₄O₆) forming a binuclear complex. HgCl₂ forms 1 : 1 “in‐cavity” complexes with the 21‐membered maleonitrile‐dithia‐21‐crown‐7 (mn21S₂O₅) ligand and the 18‐membered chinoxaline‐dithia‐18‐crown‐6 (ch18S₂O₄) ligand, respectively. The 12‐membered 4‐methyl‐benzo‐dithia‐12‐crown‐4 (meb12S₂O₂) ligand gave with two equivalents HgI₂ the compound [HgI(meb12S₂O₂)]₂[Hg₂I₆]. In the cation [HgI(meb12S₂O₂)]⁺ meb12S₂O₂ forms with the cation HgI⁺ a half‐sandwich complex.     

M(benzo‐18‐crown‐6)I4 (M = Cd,Hg): Tetraiodide,Iodide–Iodine Adduct,or an Inclusion Compound of Iodine in MI2@(benzo‐18‐crown‐6)?

M(benzo‐18‐crown‐6)I₄ (M = Cd, Hg) are obtained as red columnar crystals from the reactions of benzo‐18‐crown‐6 (b18c6), cadmium and mercury iodide, respectively, and iodine in molar ratios of 1:1:2 in acetonitrile. They both crystallize with the orthorhombic crystal system, P2₁2₁2₁, a = 833.7(1), b = 1610.9(1), c = 1846.8(1) pm, V = 2480.3(1) 10⁶·pm³, Z = 4, for M = Cd and a = 823.4(1), b = 1616.5(1), c = 1866.1(1) pm, V = 2483.8(2) 10⁶·pm³ for M = Hg. The crystal structures consist of [M(b18c6)]I₂ molecules which are connected to a slightly lengthened iodine molecule via a secondary contact, according to the formulation I₂@[MI₂@(b18c6)].     

[Ba(Benzo‐15‐Krone‐5)2](In)2: Darstellung und strukturelle Charakterisierung eines Triiodids (n = 3) und eines Heptaiodids (n = 7)

[Ba(benzo‐15‐crown‐5)₂](I₃)₂ and [Ba(benzo‐15‐crown‐5)₂](I₇)₂ can be obtained in crystalline form by reacting benzo‐15‐crown‐5 (C₁₄H₂₀O₅), barium iodide (BaI₂), and iodine (I₂) in ethan‐ole /dichloromethane. The triiodide consists of a sandwich‐like cation [Ba(benzo‐15‐crown‐5)₂]²⁺ and an isolated symmetrically linear I₃^‐ anion. The unusual I₇^‐ anion in the heptaiodide can be described as a V‐shaped pentaiodide unit, which is connected with a slightly widened iodine molecule to the rare Z‐form of the heptaiodide ion. In the crystal structure, secondary bonding distances lead to almost planar ten‐membered iodine rings, which are connected by common edges to form staircase‐like bands.     

A novel PtII–dibenzo‐18‐crown‐6 (DB18C6) complex

The novel Pt^II–dibenzo‐18‐crown‐6 (DB18C6) title complex, μ‐[tetrakis­(thio­cyanato‐S)­platinum(II)]‐N:N′‐bis{[2,5,8,­15,18,21‐hexa­oxa­tri­cyclo­[20.4.0.1^9,14]­hexa­cosa‐1(22),9(14),10,12,23,25‐hexaene‐κ⁶O]­potassium(I)}, [K(C₂₀H₂₄O₆)]₂[Pt(SCN)₄], has been isolated and characterized by X‐ray diffraction analysis. The structure analysis shows that the complex displays a quasi‐one‐dimensional infinite chain of two [K(DB18C6)]⁺ complex cations and a [Pt(SCN)₄]^2? anion, bridged by K⁺?π interactions between adjacent [K(DB18C6)]⁺ units.     

Isolated Triiodide and Pentaiodide Anions in the Crystal Structure of [Rb(Dibenzopyridino‐18‐Crown‐6)2]2(I3)(I5)

Red shiny crystals of [Rb(dibenzopyridino‐18‐crown‐6)₂]₂(I₃)(I₅) were obtained from a dichloromethane/ethanol solution of RbI, I₂ and dibenzopyridino‐18‐crown‐6. Triclinic, , a = 1494.3(1), b = 1534.1(1), c = 2412.9(2) pm, α = 76.95(1), β = 83.58(1), γ = 68.67(1)°, V = 5016.7(7) 10⁶·pm³, Z = 2. The crystal structure consists of [Rb(dbp18c6)₂]⁺ cations leaving suitable three‐dimensional channels for the linear I₃⁻ and V‐shaped I₅⁻ anions which are isolated from each other.     

4‐Methoxyanilinium tetrafluoroborate–dibenzo‐18‐crown‐6 (1/1)

In the structure of the complex of dibenzo‐18‐crown‐6 [systematic name: 2,5,8,15,18,21‐hexaoxatricyclo[20.4.0.0^9,14]hexacosa‐1(26),9,11,13,22,24‐hexaene] with 4‐methoxyanilinium tetrafluoroborate, C₇H₁₀NO⁺·BF₄⁻·C₂₀H₂₄O₆, the protonated 4‐methoxyanilinium (MB‐NH₃⁺) cation forms a 1:1 supramolecular rotator–stator complex with the dibenzo‐18‐crown‐6 molecule via N—H...O hydrogen bonds. The MB‐NH₃⁺ group is attached from the convex side of the bowl‐shaped crown, in contrast with similar ammonium cations that nest in the curvature of the bowl. The cations are associated via C—H...π interactions, while the cations and anions are linked by weak C—H...F hydrogen bonds, forming cation–crown–anion chains parallel to [011].     

Über die Decamethylferroceniumpolyiodide [(Me5C5)2Fe]Ix mit x = 3, 5 und 6,5. Darstellung und strukturelle Charakterisierung eines Triiodids (DMFc)I3, eines Pentaiodids (DMFc)I5 und eines Hexacosaiodids (DMFc)4I26

Studies on Polyhalides. 30 On Decamethylferriciniumpolyiodides [(Me₅C₅)₂Fe]I_x with x = 3, 5, 6.5: Preparation and Crystal Structures of a Triiodide (DMFc)I₃, a Pentaiodide (DMFc)I₅ and a Hexacosaiodide (DMFc)₄I₂₆ Decamethylferrocene (DMFc) may be oxidized by iodine analogous to ferrocene (Fc) to the decamethylferrocenium ion (DMFc)⁺ and precipitated as the crystalline solids decamethylferrocenium triiodide (DMFc)I₃, decamethylferrocenium pentaiodide (DMFc)I₅ and tetracisdecamethylferrocenium hexacosaiodide (DMFc)₄I₂₆. The two compounds with higher iodine content are new. These are characterized by X-ray diffraction methods on single crystals. The structures are built up from complex cations of expected geometry and isolated or remarkably connected polyiodide ions. Decamethylferrocenium triiodide C₂₀H₃₀FeI₃ crystallizes monoclinically in C2/m with a = 1489.9(4) pm, b = 1133.0(2) pm, c = 765.9(3) pm, β = 111.76(3)° and Z = 2. The crystal structure follows the CsCl-type and contains isolated triiodide ions of the linear symmetric form. Decamethylferrocenium pentaiodide C₂₀H₃₀FeI₅ crystallizes monoclinically in P2₁/c with a = 1130.0(2) pm, b = 1442.6(1) pm, c = 1716.6(2) pm, β = 96.62(1)° and Z = 4. The crystal structure may be deduced from the primitiv quadratic bundle of alternating cationic and anionic rods. It contains exceptionally isolated somewhat opened out pentaiodide ions. Tetrakisdecamethylferrocenium hexacosaiodide (C₂₀H₃₀Fe)₄I₂₆ crystallises monoclinically in P2₁/n with a = 1331.3(8) pm, b = 1319.4(4) pm, c = 3564(2) pm, β = 90.84(5)° and Z = 2. The crystal structure of this compound with unusual composition may be described as an inclusion compound with channels for the cations. The outstanding anionic grating may be derived from the primitive cubic lattice of iodide ions with iodine bridges on all edges by removing systematically 1/12 of the iodine molecules.     

Three Salts Containing the Fullerene Tetra‐Anion C604– – Synthesis,X‐Ray Single‐Crystal Structure Determination and EPR Investigation

A synthesis for four‐fold negatively charged fullerides in solution is presented. Three salts containing discrete C₆₀^4– anions were synthesized by the reduction of C₆₀ in solution using rubidium‐mercury amalgams and rubidium suboxide both in the presence of elemental mercury. The three new salts, [Rb₆DMF₁₄(C₆H₁₃N₂O₂)₂] · C₆₀ ( 1 ), [Rb(diaza‐18‐crown‐6)]₄ · C₆₀ · (en)_4.1 ( 2 ), and [Rb(benzo‐18‐crown‐6)]₄ · C₆₀ ( 3 ), were characterized by single‐crystal X‐ray diffraction. The results clearly indicate a charge of 4– for the fulleride anions. In 1 the fulleride units are ordered, and their distortion from I_h symmetry shows similarities to binary alkali metal fullerides that contain C₆₀^4– anions. In the crystal structures of 2 and 3 the C₆₀^4– anions show a rotational disorder. In all structures the 6:6 bond lengths within the fulleride are strongly enlarged compared to the ones in neutralC₆₀. EPR measurements reveal a singlet state for the C₆₀^4– anion.     

Unusual centrosymmetric structure of [M(18‐crown‐6)]+ (M = Rb,Cs and NH4) complexes stabilized in an environment of hexachloridoantimonate(V) anions

In (1,4,7,10,13,16‐hexaoxacyclooctadecane)rubidium hexachloridoantimonate(V), [Rb(C₁₂H₂₄O₆)][SbCl₆], (1), and its isomorphous caesium {(1,4,7,10,13,16‐hexaoxacyclooctadecane)caesium hexachloridoantimonate(V), [Cs(C₁₂H₂₄O₆)][SbCl₆]}, (2), and ammonium {ammonium hexachloridoantimonate(V)–1,4,7,10,13,16‐hexaoxacyclooctadecane (1/1), (NH₄)[SbCl₆]·C₁₂H₂₄O₆}, (3), analogues, the hexachloridoantimonate(V) anions and 18‐crown‐6 molecules reside across axes passing through the Sb atoms and the centroids of the 18‐crown‐6 groups, both of which coincide with centres of inversion. The Rb⁺ [in (1)], Cs⁺ [in (2)] and NH₄⁺ [in (3)] cations are situated inside the cavity of the 18‐crown‐6 ring; they are situated on axes and are equally disordered about centres of inversion, deviating from the centroid of the 18‐crown‐6 molecule by 0.4808 (13), 0.9344 (7) and 0.515 (8) Å, respectively. Interaction of the ammonium cation and the 18‐crown‐6 group is supported by three equivalent hydrogen bonds [N...O = 2.928 (3) Å and N—H...O = 162°]. The centrosymmetric structure of [Cs(18‐crown‐6)]⁺, with the large Cs⁺ cation approaching the centre of the ligand cavity, is unprecedented and accompanied by unusually short Cs—O bonds [2.939 (2) and 3.091 (2) Å]. For all three compounds, the [M(18‐crown‐6)]⁺ cations and [SbCl₆]⁻ anions afford linear stacks along the c axis, with the cationic complexes embedded between pairs of inversion‐related anions.     

Bis(adamantan‐1‐aminium) tetrachloridozincate(II) 18‐crown‐6 monohydrate clathrate

The structure of the title compound [systematic name: bis(adamantan‐1‐aminium) tetrachloridozincate(II)–1,4,7,10,13,16‐hexaoxacyclooctadecane–water (1/1/1)], (C₁₀H₁₈N)₂[ZnCl₄]·C₁₂H₂₄O₆·H₂O, consists of supramolecular rotator–stator assemblies and ribbons of hydrogen bonds parallel to [010]. The assemblies are composed of one protonated adamantan‐1‐aminium cation and one crown ether molecule (1,4,7,10,13,16‐hexaoxacyclooctadecane) to give an overall [(C₁₀H₁₈N)(18‐crown‐6)]⁺ cation. The –NH₃⁺ group of the cation nests in the crown and links to the crown‐ether O atoms through N—H...O hydrogen bonds. The 18‐crown‐6 ring adopts a pseudo‐C_3v conformation. The second adamantan‐1‐aminium forms part of ribbons of adamantan‐1‐aminium–water–tetrachloridozincate units which are interconnected by O—H...Cl, N—H...O and N—H...Cl hydrogen bonds via three different continuous rings with R₅⁴(12), R₄³(10) and R₃³(8) motifs.     

Kristallstrukturen „supramolekularer”︁ (Benzo‐18‐krone‐6)kaliumtetrathiocyanatometallate: Ein dimerer Komplex {[K(Benzo‐18‐krone‐6)]2[Hg(SCN)4]}2 und zwei isomere Komplexe [K(Benzo‐18‐krone‐6)][Cd(SCN)3] mit kettenförmigen Trithiocyanatocadmat‐Anionen

Crystal Structures of „Supramolecular”︁ Benzo‐18‐crown‐6 Potassium Tetrathiocyanato Metallates: A Dimeric Complex {[K(Benzo‐18‐crown‐6)]₂[Hg(SCN)₄]}₂ and Two Isomeric Complexes [K(Benzo‐18‐crown‐6)][Cd(SCN)₃] Containing Trithiocyanato Cadmate Anions with Chain Structures By reaction of potassium thiocyanatomercurate(II) complexes with benzo‐18‐crown‐6 (2,3‐benzo‐1,4,7,10,13,16‐hexaoxacyclooctadec‐2‐ene) crystals of {[K(benzo‐18‐crown‐6)]₂[Hg(SCN₄)]}₂ ( 1 ) were obtained. 1 crystallizes monoclinic, space group P2₁/n (non‐standard setting of P2₁/c), a = 1737.35(2), b = 1377.16(2), c = 1984.12(3) pm, β = 100.637(1)°, Z = 2. With potassium tetrathiocyanatocadmate(II) two modifications of a complex [K(benzo‐18‐crown‐6)][Cd(SCN)₃] ( 2 , 3 ), of different symmetry were formed. 2 crystallizes monoclinic, P2₁/c, a = 1158,31(3), b = 1096,55(2), c = 2028,46(2) pm, β = 99,5261(2)°, Z = 4, 3  orthorhombic, P2₁cn, a = 1105,95(3), b = 1413,07(4), c = 1617,10(5) pm, Z = 4. 1 has a dimeric structure, built up from a dication K₂(benzo‐18‐crown‐6)₂]²⁺ and two [K(benzo‐18‐crown‐6)]⁺ cations, which are bridged by two [Hg(SCN)₄]^2– anions. In 2 and 3 triply bridged infinite [{Cd(SCN)₃^–}_n] zigzag chains, stretching along screw axes, are to be found as anions. In 2 these chains exist in two conformations related by inversion symmetry, whereas in 3 only one form can be found. [K(benzo‐18‐crown‐6)]⁺ cations are linked to the anion chains via K · · · S interactions of different lengths.     

Neue Kronenether‐stabilisierte Oxoniumhalogenochalkogenate: [H3O(Dibromo‐benzo‐18‐Krone‐6)]2[Se3Br10] und [H5O2(Bis‐dibromo‐dibenzo‐24‐Krone‐8]2[Se3Br8]

Novel Oxonium Halogenochalcogenates Stabilized by Crown Ethers: [H₃O(Dibromo‐benzo‐18‐crown‐6)]₂[Se₃Br₁₀] and [H₅O₂(Bis‐dibromo‐dibenzo‐24‐crown‐8]₂[Se₃Br₈] Two novel complex oxonium bromoselenates(II,IV) and –(II) are reported containing [H₃O]⁺ and [H₅O₂]⁺ cations coordinated by crown ether ligands. [H₃O(dibromo‐benzo‐18‐crown‐6)]₂[Se₃Br₁₀] ( 1 ) and [H₅O₂(bis‐dibromo‐dibenzo‐24‐crown‐8]₂[Se₃Br₈] ( 2 ) were prepared as dark red crystals from dichloromethane or acetonitrile solutions of selenium tetrabromide, the corresponding unsubstituted crown ethers, and aqueous hydrogen bromide. The products were characterized by their crystal structures and by vibrational spectra. 1 is triclinic, space group (Nr. 2) with a = 8.609(2) Å, b = 13.391(3) Å, c = 13.928(3) Å, α = 64.60(2)°, β = 76.18(2)°, γ = 87.78(2)°, V = 1404.7(5) ų, Z = 1. 2 is also triclinic, space group with a = 10.499(2) Å, b = 13.033(3) Å, c = 14.756(3) Å, α = 113.77(3)°, β = 98.17(3)°, γ = 93.55(3)°. V = 1813.2(7) ų, Z = 1. In the reaction mixture complex redox reactions take place, resulting in (partial) reduction of selenium and bromination of the crown ether molecules. In 1 the centrosymmetric trinuclear [Se₃Br₁₀]^2? consists of a central Se^IVBr₆ octahedron sharing trans edges with two square planar Se^IIBr₄ groups. The novel [Se₃Br₈]^2? in 2 is composed of three planar trans‐edge sharing Se^IIBr₄ squares in a linear arrangement. The internal structure of the oxonium‐crown ether complexes is largely determined by the steric restrictions imposed by the aromatic rings in the crown ether molecules, as compared to complexes with more flexible unsubstituted crown ether ligands.     

Cs2[Pr6(C2)]I12 - das erste quaternäre reduzierte Halogenid mit isolierten [M6(C2)]-Clustern

Cs₂[Pr₆(C₂)]I₁₂ — the First Quaternary Reduced Halide with Isolated [M₆(C₂)] Clusters . Cs₂[Pr₆(C₂)]I₁₂ is obtained as one of the major products from the reaction of PrI₃, cesium and carbon in sealed tantalum containers at 850°C. The crystal structure triclinic, P 1 ; a=948.1(2), b=953.6(3), c=1 005.2(3) pm; α=71.01(2); β=84,68(3), γ=89.37(2)°; Z=1 contains discrete Pr₆I₁₂-type clusters elongated along the pseudo-four-fold axis to accommodate the C₂ units (d(C—C)=139 pm). The clusters are connected through common ^i?aI and ^a?iI linkages at metal vertices and edges according to Cs₂[Pr₆(C₂)ⁱI₆^i?aI_6/2]^a?iI_6/2. The cesium cations occupy interstices within the (distorted) iodide layers in a way that “Cs₂I₁₈” dimers are formed, in which Cs⁺ is surrounded by eleven I^?. On the basis of the MO scheme of [Sc₆(C₂]I₁₁, the bonding of the C² unit is discussed and compared with other cluster compounds containing C₂ units.     

Untersuchungen an Polyhalogeniden. XXVI [1]. Über N-Propylurotropiniumpolyiodide UrPrIx mit x = 5 und 7: Strukturelle Charakterisierung eines Pentaiodids und eines Heptaiodids

Studies on Polyhalides. 26. On N-Propylurotropinium Polyiodides UrPrI_x with x = 5 and 7: Crystal Structures of a Pentaiodide and a Heptaiodide The salts UrPrI_x with x = 5 and 7 are formed by the reaction of N-propylurotropinium iodide UrPrI with excess iodine I₂ at room temperature from aqueous solution. N-propylurotropinium pentaiodide C₉H₁₉N₄I₅ crystallizes monoclinically in P2₁/n with a = 1007.6(3) pm, b = 1362.5(3) pm, c = 2899.0(9) pm, β = 91.49(3)º and Z = 8. The crystal structure is built up from parallel chains of cations UrPr⁺ and pairs of V-shaped pentaiodide anions I₅^? along [0 1 0]. N-propylurotropinium heptaiodide C₉H₁₉N₄I₇ crystallizes triclinically in P1 with a = 970.4(1) pm, b = 971.1(1) pm, c = 1357.8(2) pm, α = 106.83(1)º, β = 92.28(1)º, γ = 105.17(1)º and Z = 2. The crystal structure is stacked by alternating cationic and anionic double layers along [0 0 1]. The heptaiodide layer shows a two-dimensional network.     

Di‐Benzo‐18‐Crown‐6 and its Derivatives as Ligands in the Search for Ion Channels

Based on the previously reported one‐dimensional channel system [(H₂O)?(DB18C6)(μ₂‐H₂O)_2/2][(H₃O)?(DB18C6)(μ₂‐H₂O)_2/2]I₃ ( 2 ), which is realized by stacking of crown ether molecules (DB18C6 = dibenzo‐18‐crown‐6), other synthetic approaches towards ionic channels and their results are presented in this paper. The “cutting out” approach using DB18C6 as scissor, applied on NaI, yields the compound [Na?(DB18C6)I(THF)][Na?(DB18C6)(H₂O)₂]I(THF)₂(CHI₃) ( 1 ), in high yield. It is based on a neutral and a cationic complex of sodium by DB18C6 linked via H‐bonding to give short chain fragments. The anion exchange approach, trying to replace I₃^? by Br₃^? leads to the intercalation of a cation into a DB18C6 chain in [(Me₃NPh)(DB18C6)]Br₃ ( 3 ). A similar reaction as for the synthesis of 2 , but replacing iodide with bromine, yields finally a brominated DB18C6 ligand. In the presence of iron, the compound [(H₅O₂)?(Br₄‐DB18C6)₂][FeBr₄], 4 , is observed, in which a H₅O₂⁺‐cation is encapsuled by two brominated crown ether molecules. The absence of Fe and an excess of Br₂ leads to the complexation of H₃O⁺, and co‐crystallisation of bromine in [(H₃O)?(Br₄‐DB18C6)]Br₃Br₂ ( 5 ).