Volume 64, Issue 10

By slow diffusion of pyridine (py) into an aqueous solution containing the respective metal salt and acetylenedicarboxylic acid (H 2 ADC), single crystals of coordination polymers of composition 1 ∞ [M II (H 2 O) 2 (py) 2 ADC] with M II = Zn (1) and Cd (2) were obtained. The crystal structures consist of octahedral M II N 2 O 4 units, which are connected to chains via acetylenedicarboxylate dianions. Hydrogen bonds between O atoms of the dianions and of the water molecules lead to the formation of layers perpendicular to [010]. The structure is further held together by weak aromatic stacking interactions between the pyridine ligands. Graphical Abstract Neue Koordinationspolymere mit Acetylendicarboxylat als verbrückenden und Pyridin als terminierenden Liganden / New Coordination Polymers with Acetylenedicarboxylate as Bridging and Pyridine as Terminating Ligands

1,1-Organoboration of dialkyn-1-yl(divinyl)silanes, dialkyn-1-yl(organo)(vinyl)silanes and dialkyn- 1-yl(allyl)(methyl)silane using triethylborane, BEt3, or 9-ethyl-9-borabicyclo[3.3.1]nonane, Et-9- BBN, afforded selectively silole derivatives with Si-vinyl and Si-allyl functions, respectively, bearing the dialkylboryl group in 3-position. The siloles are formed via intermolecular 1,1-alkylboration, followed by intramolecular 1,1-vinylboration. In the cases of several 3-diethylboryl-substituted siloles, smooth and essentially quantitative protodeborylation could be achieved by the reaction of the siloles with an excess of acetic acid at ambient temperature. All new siloles were characterized in solution by multinuclear magnetic resonance spectroscopy ( 1 H, 13 C, 11 B and 29 Si NMR). Graphical Abstract Siloles Bearing Si-Vinyl and Si-Allyl Functions. 1,1-Organoboration and Protodeborylation

New nickel-deficient stannides Eu 2 Ni 2−x Sn 5 were synthesized by induction melting of the elements in sealed tantalum tubes. The solid solution was studied by X-ray powder diffraction and two crystal structures were refined on the basis of X-ray diffractometer data: Cmcm, a = 466.03(4), b = 3843.1(8), c = 462.92(9) pm, wR2 = 0.0469, 692 F 2 values, 39 variables for Eu 2 Ni 1.49 (1)Sn 5 and a = 466.11(9), b = 3820.1(8), c = 462.51(9) pm, wR2 = 0.0358, 695 F 2 values, 39 variables for Eu 2 Ni 1.35 (1)Sn5. This new structure type can be considered as an intergrowth structure of CaBe 2 Ge 2- and CrB-related slabs. The striking structural motifs are nickel-centered square pyramids which are condensed via common corners and edges. The layers of condensed NiSn 5 units are separated by the europium atoms. The Ni 1 sites within the CaBe 2 Ge 2 slabs show significant defects which leads to split positions for one tin site. Eu 2 Ni 1.50 Sn 5 shows Curie-Weiss behavior and an experimental magnetic moment of 7.74(1) μ B / Eu atom, indicating stable divalent europium, as is also evident from 151 Eu Mössbauer spectra. Antiferromagnetic ordering is detected at 3.5 K. Graphical Abstract Nickel-deficient Stannides Eu 2 Ni 2–x Sn 5 – Structure, Magnetic Properties, and Mössbauer Spectroscopic Characterization

Over the last years, the synthesis and characterization of new spinel-type gallium oxonitrides were in the focus of several working groups. Our systematic investigation of the formation of the gallium oxonitride spinel phases was done under different experimental conditions and with various educts already used in former studies. The experiments took place under high-pressure/high-temperature conditions in a multianvil apparatus, starting from the end members wurtzite-structured GaN and β -Ga 2 O 3 . Beside the variation of the molar ratio of the educts (w-GaN:β -Ga 2 O 3 = 9 :1 - 1: 9), different pressures (1 - 11.5 GPa), temperatures (500 - 1350 °C), and heating protocols were studied to localize the formation area of the spinel-type gallium oxonitrides. From these results, initial conditions of 2.5 - 11.5 GPa at temperatures between 1000 - 1300 ◦C can be stated as leading to the formation of cubic, spinel-type gallium oxonitride phases. The temperature stability of the gallium oxonitride spinel phase as well as new results of the transformation of β -Ga 2 O 3 into α-Ga 2 O 3 are reported. Graphical Abstract A Systematic Investigation of the Stability Field of Spinel-type Gallium Oxonitrides

Depending on both electronic (valence electron numbers) and geometric (atom size ratios) characteristics of the contributing elements, the 1 : 1 compounds A II M of the heavier alkaline earth elements A and electron-rich transition metals M form the well known CrB or FeB structure types. Both structure types exhibit M zig-zag chains, which are stacked in different orientations. In systematic studies of the pseudo-binary section CaAg x Zn 1−x four new ternary phases with different stacking variants between the CrB (cubic stacking, c) and the FeB (hexagonal stacking, h 2 ) structure type have been prepared and characterized on the basis of single crystal X-ray data. Starting from CaAg (CrB type, orthorhombic, space group Cmcm, a = 405.22(7), b = 1144.7(2), c = 464.43(11) pm, Z = 4, R1 = 0.0197), up to 24% of Ag (CaAg 0.76 Zn 0.24 : a = 408.6(2), b = 1144.3(5), c = 460.7(2) pm, R1 = 0.0208) can be substituted by zinc without a change in the structure type. Close to the 1 : 1 ratio of Ag and Zn, the HT-TbNi structure type with the stacking sequence (hc 2 ) 2 , i. e. 33% hexagonality (CaAg 0.52 Zn 0.48 : orthorhombic, space group Pnma, a = 2345.47(6), b = 454.370(10), c = 609.950(10) pm, Z = 12, R1 = 0.0298) is formed, followed by the SrAg type with 50% hexagonality (CaAg 0.48 Zn 0.52 : orthorhombic, space group Pnma, a = 1571.0(2), b = 451.50(7), c = 609.80(9) pm, Z = 8, R1 = 0.0733). The amount of hexagonal stacking is further increased with increasing Zn content in CaAg 0.33 Zn 0.67 (Gd 0.7 Y 0.3 structure type, h 2 c stacking, 67% hexagonality, monoclinic, space group P2 1 /m, a = 610.39(9), b = 448.53(5), c = 1195.7(2) pm, β = 96.829(14)◦, Z = 3, R1 = 0.0221). Finally, a pure hexagonal stacking sequence, i. e. the FeB structure type (orthorhombic, space group Pnma, Z = 4) is observed from CaAg 0.14 Zn 0.86 (a = 804.57(2), b = 443.050(10), c = 611.350(10) pm, R1 = 0.0131) to CaAg 0.06 Zn 0.94 (a = 806.1(3), b = 441.0(2), c = 610.4(3) pm, R1 = 0.0255). Intriguingly, the series ends with the binary compound CaZn, which again crystallizes with the CrB structure type exhibiting cubic stacking of the zig-zag chains only (0% hexagonality). In an accompanying computational study, the chemical bonding in the series Ca(Ge/Ga/Zn/Ag) of isotypic binary metallides with variable valence electron numbers has been analyzed using FP-LAPW band structure methods. The electronic structures of the two border stacking variants are compared using the crystal data of CaZn (CrB type) and CaAg 0.06 Zn 0.94 (FeB type). Geometrical and electronic criteria are used to compare and discuss the stability ranges of the different stacking variants inbetween the CrB and the FeB structure type found in polar intermetallic 1 : 1 phases. Graphical Abstract CaAg x Zn 1– x : Zwischen CrB- und FeB-Strukturtyp – Eine Studie zu elektronischen Einflüssen auf die Stapelung von Zick-Zack-Ketten in polaren Erdalkalimetall-Monometalliden / CaAg x Zn 1−x : Between CrB and FeB Structure Type – A Study on Electronic Factors Influencing the Stacking of Zig-zag Chains in Polar Alkaline Earth Monometallides

Reactions of silver(I) salts with 4-amino-4H-1,2,4-triazole (4-NH 2 -tz) in a 1 : 1 molar ratio yield four new silver adducts, namely [Ag(4-NH 2 -tz)](CF 3 SO 3 ) (1), [Ag(4-NH 2 -tz) 1.75 ](ClO 4 ) (2), [Ag(4- NH 2 -tz) 1.75 ](BF 4 ) (3) and [Ag(4-NH 2 -tz) 1.75 ](NO 3 ) (4). X-Ray analysis shows that 1 exhibits a 3D cationic [Ag(4-NH 2 -tz)] + metal-organic framework of srs topology; 2, 3 and 4 are isostructural and display an infinite chain structure containing an Ag 4 tz 6 cluster. Graphical Abstract Synthesis and Structures of Silver(I) Adducts with 4-Amino-4H-1,2,4-triazole

A highly efficient one-pot procedure for the synthesis of complexes of the type [Ir(COD)(Phox)]X, where Phox is a (chiral) phosphinooxazoline ligand, X = PF 6 or B[(3,5-(CF 3 ) 2 C 6 H 3 )] 4 (BARF), is developed. Former reported syntheses demanded the isolation of pure ligands by column chromatography, but the ligands tend to adsorb irreversibly on silica. Moreover, the chromatography has to be performed with careful exclusion of air. The present method avoids this difficulties. The yields of the syntheses are comparable with those starting from the pure ligands. The method is also suitable for the preparation of complexes of the type [Rh(COD)(Phox)]BARF and [Rh(Phox) 2 ]BARF. Graphical Abstract Highly Efficient Synthesis of (Phosphinodihydrooxazole)- (1,5-cyclooctadiene) Iridium Complexes

Two types of lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) for the labelling of biomolecules were investigated by HPLC, MS and NMR spectroscopy. The elution behavior of lanthanide complexes of N-functionalized DOTA [1,4,7,10-tetraazacyclododecane- 1,4,7-triacetic acid-10-maleimidoethylacetamide (nDOTA-Mal) and 1-{2-[4-(maleimido- N-propylacetamidobutyl)amino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane-4,7,10-triacetic acid (nDOTA-Bu-Mal)] and C-functionalized DOTA [2-{4-(maleimido-N-propylacetamido)benzyl}-1,4, 7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (cDOTA-Bnz-Mal) and 2-(4-isothiocyanatobenzyl)- 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (cDOTA-Bnz-NCS)] was compared. N-functionalized lanthanide DOTA complexes coelute as required for their use as ICAT-analogous reagents. The complexation of the C-functionalized DOTA with lanthanides results in two fractions separable by HPLC. Coelution is observed for the main fractions of the lanthanide complexes. The retention times of the minor fractions show a dependence on the ionic radii of the metal ions. MALDI spectra of lanthanide-DOTA-peptide conjugates including different monoisotopic lanthanides demonstrate the advantage of the mass variations for extensive peptide and protein investigations. Graphical Abstract Elution Behavior and Structural Characterization of N- and C-functionalized DOTA Complexes for the Labelling of Biomolecules

A proline-derived silanol, was designed as a novel potential organocatalyst, and synthesized starting from the tetrazole 3. The central idea was the combination of an acidic (tetrazole) and a basic functionality (pyrrolidine) with a silanol moiety in the same molecule. The synthesis of 7 was performed in four reaction steps starting with the tetrazole 3. In the solid state (X-ray crystal structure analysis) the crucial functional groups show a favorable orientation. A chiral HPLC method and a chiral capillary electrophoresis method have been established for the investigation of the kinetic resolution of the racemic alcohols 9 and 11. Acetylation reactions of alcohols were not accelerated by the organocatalyst 7, and the produced ee values were rather low. Graphical Abstract Synthesis of a Silanol-substituted Proline Analog as Organocatalyst

2,3-Dihydro-1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (1) reacts with an excess of hexafluorobenzene in the presence of boron trifluoride diethyletherate to give 1,3-diisopropyl-4,5- dimethyl-2-(perfluorophenyl)imidazolium tetrafluoroborate (2). Solutions of 2 exhibit an equilibrium consisting also of hexafluorobenzene and 2,2ʹ-(perfluoro-1,4-phenylene)bis(1,3-diisopropyl- 4,5-dimethylimidazolium)bis(tetrafluoroborate) (3) which is obtained from 1 and hexafluorobenzene in the ratio 2 : 1 on a preparative scale. Similar to 2, 2-(4-cyano-2,3,5,6-tetrafluorophenyl)-1,3- diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (4), 2-(2,4-dicyano-2,5,6-trifluorophenyl)- 1,3-diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (5), and 2-(4,6-difluoro-1,3,5-triazin-2- yl)-1,3-diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (6) are obtained from 1 and perfluorobenzonitrile, 1,3-dicyano-2,4,5,6-tetrafluorobenzene, and 2,4,6-trifluoro-1,3,5-triazin, respectively. The FAB mass spectra of compounds 2 - 6 and the results of the crystal structure analyses of compounds 2 - 4 are discussed. Graphical Abstract Nucleophilic Aromatic Substitution with 2,3-Dihydro-1,3-diisopropyl- 4,5-dimethylimidazol-2-ylidene

The (E,E)-distyrylbenzenes 1a, b with terminal donor-acceptor substitution were prepared by a sequence of four reaction steps including two Wittig-Horner reactions. The products form smectic mesophases, are photostable, and should permit an electric orientation/reorientation, because of their strong dipole character. Graphical Abstract Mesomorphic Donor-Acceptor-substituted 1,4-Distyrylbenzenes

A wide variety of 3,5-dicarboethoxy-1,4-dihydropyridines and 3,5-diacetyl-1,4-dihydropyridines are aromatized to the pyridine derivatives by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) at room temperature and under microwave irradiation. An electron transfer-induced mechanism is proposed for this reaction which is influenced by the nature of the solvent, the nature of the substituents located on 3-, 4- and 5-positions of the 1,4-dihydropyridine ring, and the presence of oxygen or argon atmosphere. Graphical Abstract Electron Transfer-induced Aromatization of 1,4-Dihydropyridines

An efficient and direct procedure for the synthesis of pyrido[3,2-d:6,5-dʹ]dipyrimidine derivatives under microwave-assisted conditions is been described. The structures of the products were characterized by elemental analyses, and their IR, 1H NMR, 13C NMR, and MS spectra. Graphical Abstract 5-Aminouracil as a Building Block in Heterocyclic Synthesis, Part II. One-pot Synthesis of Pyrido[3,2-d:6,5-dʹ]dipyrimidines under Microwave Irradiation without Catalyst

From the dichloromethane extract of the marine green alga Ulva fasciata Delile, collected from the Mediterranean coast of Egypt, three new fatty acids, namely, (E)-11-oxo-octadeca-12-enoic acid (1a), (E)-11-hydroxy-octadeca-12-enoic acid (2a) and 6-hydroxy-oct-7-enoic acid (3a) together with cholesterol were isolated. Analysis of the unpolar part of the extract using GC-MS detected the existence of further ten compounds, namely, dimethylsulfoxide, dimethylsulfone, phenylacetamide, 6,10,14-trimethyl-pentadecan-2-one, 8-heptadecene, dodecane, tridecane, 4-oxo-pentanoic acid, hexadecanoic acid, and the naturally new 1,1ʹ-bicyclohexyl. Structures of the isolated compounds 1a - 3a were confirmed by spectroscopic analyses including mass spectra (EI-MS, HR/ESIMS), 1D and 2D NMR experiments, and by the synthetic conversion into their corresponding methyl esters 1b - 3b. The algal extract and its components were comparatively examined against several pathogenic microorganisms, and brine shrimps for cytotoxicity. Graphical Abstract Three New Unsaturated Fatty Acids from the Marine Green Alga Ulva fasciata Delile

The reduction of a partially deprotonated bishydroxylamine complex {( t Bu 2 Ga) 2 [cyclo-ON(Me)(CH 2 ) 2- (Me)NO][HON(Me)(CH 2 ) 2 (Me)(H)NO]} with a reagent composed of titanium tetrachloride and methyllithium leads to the reduction of one of the N-O groups to an amine function affording the salt {( t Bu 2 Ga)[cyclo- ON(H)(Me)(CH 2 ) 2 NHMe]}+ { t Bu 2 GaCl 2 } − . This has been characterised by 1 H and 13 C NMR spectroscopy, by elemental analysis and by single crystal X-ray diffraction, showing the neutral amine/hydroxylamine ligand to be present in its tautomeric aminoxide form. The molecules form hexameric cyclic aggregates by N-H···Cl hydrogen bonds. Graphical Abstract Partial Reduction of the N–O Functions of Partially Deprotonated Bis(hydroxylamine) Complexes

Single crystals of [Me 2 BiOMe] ∞ (1) formed in the reaction of Me3Bi with oxygen in benzene have been analysed by X-ray crystallography (orthorhombic, Pnma, Z = 4, a = 8.254(2), b = 9.9020(10), c = 7.0430(10) Å, T = 173(2) K).