Volume 65, Issue 9

The dissolution of the ternary material K 6 Rb 6 Si 17 in liquid ammonia yields the solvate compound Rb 4 Si 9 ・ 5NH 3 , which contains fourfold negatively charged nine atom silicon clusters Si 9 4− . Using additionally the [2.2.2] cryptand during the dissolution results in the solvate [K(2.2.2- crypt)]2Si 5 ・ 4NH 3 , in which the Si 5 2− anion is present in the crystal structure. The Si 5 2− anion has the shape of a nearly ideal trigonal bipyramid. The starting material K 6 Rb 6 Si 17 contains both Si 4 4− and Si 9 4− Zintl anions. In ammoniate crystal structures, Si 9 4− anions are accessible independently of Si 4 4− anions, and ammonia of crystallisation plays a major role in the observed crystal symmetry. For the cryptate structures of Si 5 2− and Ge 5 2− anions ammonia of crystallisation is obligatory despite the loss of crystal symmetry compared to the crystal structures of the heavier homologues Pb 5 2− and Sn 5 2− . Graphical Abstract Dissolving Silicides: Syntheses and Crystal Structures of New Ammoniates Containing Si 5 2– and Si 9 4– Polyanions and the Role of Ammonia of Crystallisation

Crystal structures of the cyanoplatinates A 2 [Pt(CN) 4 X 2 ] (A = Rb, Cs; X = Cl, Br, I) have been determined by single-crystal analysis and X-ray powder diffraction. The compounds were synthesized by metathesis from Ba[Pt(CN) 4 ] ·4 H 2 O and alkali metal sulfates, and by subsequent oxidation with the respective halogens. The crystals were grown by slowly concentrating respective aqueous solutions. The PtIV cations are octahedrally coordinated by four cyanide ligands and two halogen atoms, the latter being located in trans positions. Rb 2 [Pt(CN) 4 Cl 2 ]: triclinic, P¯1 (Z = 2), a = 6.7779(2), b = 9.3149(3), c = 9.6707(3) Å , α = 89.37(0), β = 76.05(0), γ = 72.98(0)◦, V = 565.42(2) Å3, N` hkl = 5616, R(F)N` = 0.0273; Rb 2 [Pt(CN) 4 I 2 ]: monoclinic, P2 1/c (Z = 2), a = 7.4239(2), b = 9.2486(2), c = 9.1189(2) Å , β = 107.22(3)◦, V = 598.04(6) Å3, N` hkl = 2917, R(F)N` = 0.0295; Cs 2 [Pt(CN) 4 I 2 ]: monoclinic, P2 1/c (Z = 2), a = 7.6740(4), b = 9.5397(5), c = 9.3474(5) Å , β = 106.46(0)◦, V = 656.3(2) Å3, Z = 2, N` hkl = 2738, R(F)N` = 0.0283; Cs 2 [Pt(CN)4Cl2]: monoclinic, C 2/c (Z = 4), a = 17.947(4), b = 7.395(2), c = 12.031(3) Å , β = 131.904(1)◦, V = 1188.4(5) Å3, R-wp = 2.77; Cs 2 [Pt(CN) 4 Br 2 ]: monoclinic, C 2/c (Z = 4), a = 18.404(1), b = 7.2819(5), c = 12.4156(8) Å , β = 132.156(1)◦, V = 1233.5(1) Å3, N` hkl = 2566, R(F)N` = 0.0268. All compounds were characterized by differential thermal analysis, thermogravimetry, and infrared and Raman spectroscopy. Graphical Abstract Cyanoplatinate Halides – Synthesis, Crystal Structure Analyses and Vibrational Spectroscopy of Compounds A 2 [Pt(CN) 4 X 2 ] (A = Rb, Cs; X = Cl, Br, I)

Structural characterization of the solvent-free ionic complex K[(η 5 -C 5 H 5 )Mo(CO) 3 ] and the molybdenum boryl complex [(η 5 -C 5 H 5 )(OC) 3 Mo-{B(NMe 2 )-B(NMe 2 )Br}] is reported. Graphical Abstract Molybdenum-Boron Bonds in the Crystal – Structural Characterization of K[(η 5 -C 5 H 5 )Mo(CO) 3 ] and[(η 5 -C 5 H 5 ) (OC) 3 Mo-{B(NMe 2 )-B(NMe 2 )Br}]

Salts of alkaline earth metal cations sequestered in dibenzo-18-crown-6 (Db18c6) and benzo-15- crown-5 (B15c5), respectively, with I 5 − , I 7 − and I 8 2− as the anions, have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. [Ca(Db18c6)(H 2 O) 3 ](I 5 ) 2- (Db18c6)(H 2 O) (1): monoclinic, P21 (no. 4), a = 1322.1(2), b = 1849.1(2), c = 1344.0(2) pm, β = 114.70(1)◦, V = 2985.2(6) × 10 6 pm 3 , Z = 2; [Sr(B15c5) 2 ](I 7 ) 2 (2): triclinic, P1 (no. 2), a = 973.9(5), b = 1244.0(5), c = 1293.3(5) pm, α = 115.28(1), β = 90.18(1), γ = 104.57(1)◦, V = 1360.2(10) × 10 6 pm 3 , Z = 2; [Ba(Db18c6)2]I 8 (3): orthorhombic, Pbcn (no. 60), a = 1452.0(2), b = 1924.6(2), c = 1912.1(2) pm, V = 5343.3(10) × 10 6 pm 3 , Z = 4. Compound 1 contains two crystallographically independent V-shaped pentaiodide anions, I 5 −, which are linked to dimers by weak interionic contacts. The unusual heptaiodide anion, I 7 − , in 2 can be described as a V-shaped pentaiodide unit, which is connected to a slightly widened iodine molecule to give the rare Z form. Secondary bonding distances lead to almost planar ten-membered iodine rings, which are connected through common edges to form ribbons with staircase-like folding. 3 is built of sandwich-like cations and centrosymmetric octaiodide anions, I 8 2− . An inspection for secondary contacts reveals that the iodine substructure of 3 consists of essentially isolated octaiodide units. Graphical Abstract Penta-, Hepta- und Oktaiodid-Anionen in Salzen mit Erdalkalimetall-Kronenether-Kationen / Penta-, Hepta-, and Octaiodide Anions in Salts with Alkaline Earth Metal Crown Ether Cations

Two new lead(II) complexes [Pb(pcih)(bha)] (1) and [Pb(pcih)(NO 3 )] (2, Hpcih = 1,4-bis(3-pyridyl)- 2,3-diazo-1,3-butadiene, Hbha = 2-hydroxybenzoic acid) have been synthesized by solvothermal methods and structurally characterized. The single-crystal X-ray data show that the coordination spheres of the Pb 2+ ions in 1 and 2 are hemidirected with stereochemically active electron lone pairs. There are some significant secondary Pb... N and Pb... interactions which produce two different extended structures, namely a 1D chain in 1 and a 2D layer in 2. Both 1 and 2 exhibit fluorescence properties at room temperature. Graphical Abstract Two New Hemidirected Lead(II) Complexes: [Pb(pcih)(bha)] and [Pb(pcih)(NO 3 )]

The surface functionalisation of gold nanoparticles (GNPs) with luminescent platinum complexes has been investigated, utilising α-lipoic acid derivatives for GNP stabilisation. Model complexes have been studied to mimic the chemisorption chemistry required to afford GNPs protected by an α-lipoic acid-based ligand shell with terminal functionalisation suitable for metal coordination, and the unambiguous binding of the cyclic disulfide moiety at a zero-valent precious metal core through oxidative addition has been confirmed by X-ray crystallography. Subsequently, gold nanoparticles bearing the α-lipoic acid-based ligand shell have been prepared and characterised, and a synthetic methodology for the immobilisation of PtII luminophores onto their surface has been established. Graphical Abstract Gold Nanoparticles Bearing an α-Lipoic Acid-based Ligand Shell: Synthesis, Model Complexes and Studies Concerning Phosphorescent Platinum(II)-Functionalisation

A seven-coordinate manganese(II) complex with the tripodal tetradentate ligand tris(N-methylbenzimidazol- 2-ylmethyl)amine (Mentb), with composition [Mn(Mentb)(α-methacrylate)(DMF)]- (ClO 4 ) · (DMF), was synthesized and characterized by elemental analysis, electrical conductivity, and IR and UV/Vis spectral measurements. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. The MnII cation is bonded to a Mentb ligand, an α-methacrylate ligand and a DMF molecule through four N atoms and three O atoms, resulting in a seven-coordinate geometry. Cyclovoltammograms of the complex indicate a quasireversible Mn 3+ /Mn 2+ couple. The X-band EPR spectrum of the complex exhibits a six-line manganese hyperfine pattern with g = 2, A = 91, and confirms that the material is high-spin Mn(II).

(C 5 H 7 N 2 ) 3 (AsMo 12 O 40 )・2C 5 H 6 N 2 ・1.5H 2 O was hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Crystal data: monoclinic, P2 1/n , a = 13.310(3), b = 22.399(5), c = 19.820(4) A° , β = 99.99(3) ◦, V = 5819(2) °A 3 , Z = 1, wR(F2) = 0.1345. The structure consists of Keggin-type [AsMo12O40]3− polyoxoanions. The title compound has a high catalytic activity for the oxidation of acetone tested in a continuous-flow fixed-bed micro-reactor. When the initial concentration is 5.3 g m −3 in air and the flow rate is 2.5 mL min −1 , the acetone is completely eliminated at 150 ◦C . Graphical Abstract Hydrothermal Synthesis, Crystal Structure and Catalytic Properties of a Novel Polyoxometalate: (C 5 H 7 N 2 ) 3 (AsMo 12 O 40 ) ·2C 5 H 6 N 2 · 1.5H 2 O

Two new cyano-bridged trinuclear heterometallic complexes [Ca 2 (phen) 4 (ClO 4 )(H 2 O) 3 - Fe(CN) 6 ]・H2O (1) and [Ca 2 (phen) 4 (CH 3 COO)(H 2 O) 3 Fe(CN) 6 ]・2H 2 O (2) (where phen = 1,10- phenanthroline) have been synthesized and characterized by single-crystal X-ray diffraction techniques, IR spectroscopy and thermogravimetric analysis. The structure of complex 1 features a central [Fe(CN)6]3− unit that links a monocation [Ca(phen) 2 (H 2 O)(ClO 4 )]+ and a dication [Ca(phen) 2- (H 2 O) 2 ] 2+ via two trans cyanide bridges. Similarly, complex 2 also features a central [Fe(CN) 6 ] 3− unit that links a monocation [Ca(phen) 2 (H 2 O)(CH 3 COO)]+ and a dication [Ca(phen) 2 (H 2 O) 2 ] 2+ via two trans cyanide bridges. In 1 and 2, both Ca centers are seven-coordinated and achieve a pentagonal- bipyramidal geometry whereas the Fe center in both the complexes possesses a distorted octahedral geometry. Intra- and intermolecular hydrogen bonding networks are present in 1 and 2 that impart the overall molecular stability to both the systems. Graphical Abstract Synthesis and Structural Aspects of Two Trinuclear Cyano-bridged Heterometallic Complexes with Monodentate Coordination of Perchlorate and Acetate Anions

The family of horsetails (Equisetaceae) is characterized through their high content of silica (SiO 2 ), which is the highest in known vascular plants. This work has focussed on two species of this family, Equisetum hyemale and Equisetum telmateia, where the biomorphous silica is deposited basically as amorphous SiO 2 in the outer epidermis of the plants. As source of SiO 2 , the original plant material was air-dried and carved or powdered. For the isolation process the biomaterial was pre-treated with aceotropic HCl. This pre-treatment has the advantage of the extraction of high amounts of the natural inorganic matrix. In a second step the organic matrix was removed by a thermal oxidative process in the temperature range of 275 - 1200 ◦ C to isolate the biogenic silicon dioxide from the perennial plant. Parameters of time, temperature and the thermal gradient were varied to optimize the process and to get products with the highest possible surface area. Furthermore, the particle morphology of the biogenic SiO 2 from leaves and stems was examined separately. The silica deposits were characterized by optical microscopy, scanning electron microscopy, infrared spectroscopy, gravimetry, nitrogen sorption analysis, and sedimentation analysis. Graphical Abstract Morphology and Structure of Biomorphous Silica Isolated from Equisetum hyemale and Equisetum telmateia

A series of new 2,2` -bipyridine/1,2-dithiolate transition metal complexes has been synthesised and characterised. As 1,2-dithiolate ligands 1,2-dithiooxalate (dto) and 1,2-dithiosquarate (dtsq) were used. It follows from the IR spectra that the multidentate dithiolate ligands coordinate exclusively via their sulfur atoms forming an MN 2 S 2 coordination sphere. The central metal ions (M) are Cu 2+ , Ni 2+ , Pd 2+ , Pt 2+ , and Zn 2+ . The complex [Cu II (bpy)(dto)] could be studied by EPR spectroscopy and was measured as powder, diamagnetically diluted in the isostructural [NiII(bpy)(dto)] host structure. The spin density contribution calculated from the experimental parameters is compared with the electronic situation in the frontier orbitals, namely in the semi-occupied SOMO of the copper complex, derived from quantum chemical calculations on different levels (EHT and DFT). Graphical Abstract 2,2`-Bipyridin-1,2-dithiolat Gemischtligand-Komplexe. Synthese, Charakterisierung und EPR-Spektroskopie / 2,2`-Bipyridine-1,2-dithiolate Mixed Ligand Complexes. Synthesis, Characterisation and EPR Spectroscopy

A new synthetic pathway for the preparation of ω-functionalized 2-iodophenyl esters as starting materials for the synthesis of substituted phosphanes is described. A radiolabeling of these esters with fluorine-18 has led to building blocks which were reacted with HPPh 2 in a Pd-catalyzed P-C cross coupling to establish new phosphanes. These compounds can be applied as mild and bioorthogonal radiolabeling agents by means of the traceless Staudinger ligation. A route to access this class of compounds has been established. Graphical Abstract Synthesis and Radiofluorination of Iodophenyl Esters as Tool for the Traceless Staudinger Ligation

The crystal structure of tropylium bromide, C 7 H 7 + Br − , was solved and refined in space group type R¯3m with rotationally disordered C 7 rings. Restraints of identical 1,2- and 1,7-C-C bond lengths as well as identical 1,3- and 1,6-C-C separations within a flat C 7 H 7 moiety were applied. The refinement converged to a regular C 7 heptagon with C-C bond lengths of 139.1(1) pm. C 7 H 7 + Br − reacts with Mo(CO) 3 (CH 3 CN) 3 to form C 7 H 7 Mo(CO) 2 Br. Graphical Abstract Die rotationsfehlgeordnete Kristallstruktur von Tropyliumbromid C 7 H 7 + Br – / The Rotationally Disordered Crystal Structure of Tropylium Bromide C 7 H 7 + Br −

4-Alkyl- or 4-aryl-1,4-dihydropyridine derivatives were oxidized to the pyridine derivatives by tetrabutylammonium peroxydisulfate (n-Bu 4 N) 2 S 2 O 8 (TBAPD) in combination with basic alumina in refluxing acetonitrile and also in the absence or presence of basic alumina under microwave irradiation. The presence of basic alumina plays an important role in the reaction mechanism. Whereas oxidation under thermal condition is assumed to occur through an ionic mechanism, ionic and also radical mechanisms are proposed for the reactions under microwave irradiation. Graphical Abstract Catalytic Effect of Basic Alumina in the Dehydrogenation of 1,4-Dihydropyridines with Tetrabutylammonium Peroxydisulfate

An efficient and direct procedure for the synthesis of 2,2`-(1,4-phenylene)bis-3,4-dihydro-2H-1,3- thiazin-4-one derivatives is described. Oxidation of the latter and their base-catalyzed recyclization has been studied. The products were characterized by elemental analyses, and IR, 1H NMR, and 13C NMR spectra. Graphical Abstract Synthesis of 2,2`-(1,4-Phenylene)bis-3,4-dihydro-2H-1,3-thiazin-4-ones and their Facile Recyclization to 2,2`-(1,4-Phenylene)bis(pyrimidin-4-one) and/or 2,2`-(1,4-Phenylene)-bis-(thieno[2,3-d]pyrimidin-4(1H)-one) Derivatives

In dependence on the molar ratio, the reaction of primary anthranilamides 3 with oxalyl chloride produced 1H-benzo[e][1,4]diazepine-2,3,5(4H)-triones 4 or 10-substituted 11a-chloro-benzo[e]- oxazolo[3,2-a][1,4]diazepine-2,3,5,11(10H, 11aH)-tetraones 5, the structures of which were unambiguously proven by X-ray diffraction analysis. Graphical Abstract Cyclic Oxalylation of Primary N-Substituted Anthranilamides: 1H-Benzo[e][1,4]diazepine-2,3,5(4H)-triones and 11a-Chlorobenzo[ e]oxazolo[3,2-a][1,4]diazepine-2,3,5,11(10H,11aH)-tetraones

Two new compounds, ent-8(9)-pimarene-20-hydroxy-16-nor-15-oic acid (1) and 20S,24-epoxy- 25,26,27-trisnor-24-oxo-3,4-seco-dammar-4(28),22-dien-3-oic acid (2), along with four known compounds have been isolated from the bark of Dysoxylum hainanense. The new structures were elucidated by spectroscopic techniques (NMR, MS, UV, IR and optical rotation). The known compound, ent-8(9)-pimarene-15,16-diol (3), was reported from D. hainanense for the first time. Graphical Abstract Two New Compounds from the Bark of Dysoxylum hainanense

The alkaloidal fraction of Alstonia scholaris leaves shows anti-inflammatory and analgesic bioactivity in vivo. A phytochemical study on this fraction led to the isolation of two novel alkaloids, scholarisine I and (±)-scholarisine II. Their structures were elucidated on the basis of spectroscopic methods, and a possible biogenesis is proposed. (±)-Scholarisine II selectively inhibited the inducible COX-2 rather than COX-1, and also markedly inhibited 5-LOX, comparable to positive controls. Graphical Abstract Novel Alkaloids from Alstonia scholaris

Hydrothermal reaction of Cd(II) acetate with the bridging ligand m-H 4 bptc (m-H 4 bptc = biphenyl-2,3`,3,4`-tetracarboxylic acid) yielded a new 2D metal-organic coordination polymer with helical chains in the solid state namely {[Cd 2 (m-bptc)(H 2 O) 6 ]·(H 2 O)5}n (1). The helices are further connected through hydrogen bonds to give a threedimensional supramolecular network. The thermal stability of complex 1 was studied by thermogravimetric (TG) and differential thermal analysis (DTA). Compound 1 exhibits photoluminescence with an emission maximum at ca. 399 nm upon excitation at 360 nm. Graphical Abstract Hydrothermal Synthesis, Crystal Structure and Properties of a 2D Network of Cd(II) Coordination Polymers with Helical Chains

The title complex, [Mn 2 (glu)(L) 2 (HL) 2 ]・0.5H 2 O (H 2 glu = glutaric acid, HL = 2-(2-chloro-6-fluorophenyl)-1Himidazo[ 4,5-f][1,10]phenanthroline) has been synthesized using a hydrothermal method and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal data: C 162 H 88 Cl 8 F 8 Mn 4 N 32 O 9 , triclinic, space group P1¯, a = 14.932(5), b = 16.414(5), c = 17.891(5) Å , α = 115.851(5), β = 91.288(5), γ = 112.894(5)◦, V = 3536.4(19) Å 3 , Z = 1. Compound 1 exhibits 1D chains which are further stacked by C-H...π interactions to give two-dimensional supramolecular layers. Graphical Abstract Synthesis, Structure and Characterization of a Novel Two-Dimensional Supramolecular Mn(II) Coordination Polymer Constructed from a 1,10-Phenanthroline Derivative and a Flexible Dicarboxylate