Volume 70, Issue 10

The equiatomic Ce XX ′ phases ( X and X ′ = elements of the 3 rd , 4 th , or 5 th main group) extend the large series of Ce TX intermetallics ( T = electron-rich transition metal). These phases crystallize with simple structure types, i.e. ZrNiAl, TiNiSi, CeScSi, α-ThSi 2 , AlB 2 , and GdSi 2 . In contrast to the Ce TX intermetallics one observes pronounced solid solutions for the Ce XX ′ phases. The main influence on the magnetic ground states results from the absence of d electrons. All known Ce XX ′ phases show exclusively trivalent cerium and antiferro- or ferromagnetic ordering at low temperatures. The crystal chemical details and some structure-property relationships are reviewed.

A coordination polymer {[Mn(BDC-Cl 4 )(DMF) 4 ](H 2 BDC-Cl 4 )} n ( 1 ) (H 2 BDC-Cl 4 = 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid) was synthesized by a resin-assisted solvothermal method and isolated by a flotation method in carbon tetrachloride. Complex 1 shows a one-dimensional wave-like coordination structure in the solid state. It is readily dissolved in water. The complex has been characterized using elemental analysis, IR spectroscopy, molecular conductivity, thermogravimetric analysis, and single-crystal and powder X-ray diffraction techniques.

Reaction of 3,4,5,6-tetrachloro-1,2-benzenedicarboxylyic acid (1,2-H 2 BDC-Cl 4 ) with transitional metal salts at room temperature in mixed DMF/H 2 O solvent affords three complexes formulated as [Cu(1,2-HBDC-Cl 4 ) 2 (DMF) 2 ] ( 1 ), {[Cd(1,2-HBDC-Cl 4 ) 2 (H 2 O) 4 ]·2DMF} ( 2 ), and {[Ni(1,2-BDC-Cl 4 )(H 2 O) 5 ]·DMF·H 2 O} ( 3 ) (DMF = N,N-dimethylformamide). All these complexes have been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray crystallography. In 1 , the Cu II ion is four-coordinated with a square-planar geometry formed by two 1,2-HBDC-Cl 4 anions and two DMF ligands; in 2 , the Cd II ion takes an octahedral geometry coordinated by two 1,2-HBDC-Cl 4 anions and four aqua ligands; while in 3 , the Ni II ion is octahedrally coordinated by one 1,2-BDC-Cl 4 dianion and five aqua ligands. Intermolecular O–H···O hydrogen bonds and Cl···Cl (or C–H···Cl) interactions provide a significant contribution to stabilizing the three mononuclear structures in the solid state. The results suggest that structural differences among them are attributed to the influence of transition metal ions. The fluorescence of the complexes and of 1,2-H 2 BDC-Cl 4 has been investigated. No significant metal effect has been observed.

A new complex of Hg(II) with 6-methoxyquinoline (C 10 H 9 NO-6MQ) has been synthesized and characterized. The structure of the complex Hg(6MQ)Cl 2 was determined by single crystal X-ray diffraction. It crystallizes in the monoclinic space group P 2 1 / c with a = 3.9139(3), b = 26.3400(2), c = 10.9090(9) Å, β = 89.833(6)°, V = 1124.6(1) Å 3 and Z = 4 molecules per unit cell. The coordination geometry of the mercury(II) center can be described as a distorted square pyramid formed by one nitrogen atom of the 6MQ and four chlorine atoms. Fourier transform infrared, Raman and UV/Vis spectroscopic studies have been carried out to characterize the compound, using theoretical calculations for the assignment of the experimentally observed bands. The thermal behavior was investigated by thermogravimetric analysis. The quantum yield of singlet molecular oxygen production Φ Δ was measured with steady-state methods in ethanol, using 9,10-dimethylanthracene (DMA) as actinometer and Bengal rose as reference photosensitizer. The resultant singlet molecular oxygen was detected indirectly by photooxidation reactions of DMA. The luminescence properties have also been studied.

An effective and regioselective synthesis of aminomethylated daidzein derivatives using a Mannich reaction of daidzein, formaldehyde with a variety of amines under ultrasound irradiation is described. The structures of the products were characterized by HRMS, 1 H NMR, 13 C NMR and 2D NMR spectra. Parallel reactions showed that ultrasound irradiation accelerated the reaction rate and improved the yields.

The reaction of S -nicotine with hydroiodic acid in the presence of iodine gave the new polyiodide-containing salt nicotine-1,1′-diium bis(triiodide)-diiodine (1/1) (C 10 H 16 N 2 ) [I 3 ] 2 ·I 2 ( 1 ). The title compound has been characterised by spectroscopic methods (Raman and IR) and single-crystal X-ray diffraction. The asymmetric unit of the title structure consists of one dication, two triiodide anions, and one iodine molecule, all located in general positions in the non-centrosymmetric space group P 1. One of the two crystallographically independent triiodide anions and the doubly protonated nicotinium dication form hydrogen-bonded chains along b , which are arranged parallel to each other in the ½ bc plane. The second crystallographically independent triiodide anion and the iodine molecule form an I 5 – moiety, which is end-on connected to two symmetry-related anions resulting in polyiode zig–zag chains along the [0 1 1̅] direction. These polyiodide chains are stacked parallel to each other in the 0 bc plane. The Raman spectrum of the title compound shows characteristic lines in the 50–200 cm –1 range, which are in excellent agreement with the findings derived from the crystal structure.

Stimulated by a report from (R. Köster, G. Benedikt, M. A. Grassberger, Liebigs Ann. Chem . 1968 , 719 , 187.) on a carbaborane, for which the structure of 2,3,4,5,-tetraethlyl-1-methyl-2,5- μ -(ethyl-1′,1′-diyl)-1-carba- arachno -pentaborane(10) 1 was proposed, an independent synthesis was developed. Diethyl(ethynyl)borane was generated in situ in the presence of a large excess of “Et 2 B–H” (hydride bath) by ethynyl/H exchange, using ethynyl(trioctyl)tin to react in a mixture with diethyl(vinyl)borane at low temperature. Hydroboration and Et 2 B–H-catalysed condensation afforded 1 , as shown by 11 B, 13 C NMR spectroscopy and DFT calculations. Thermal degradation of 1 gave 2,3,4-triethyl-1,5-dimethyl-1,5-dicarba- closo -pentaborane(5), whereas the pentaethyl-1,5-dicarba- closo- pentaborane(5) resulted from thermally induced decomposition of other suitably substituted arachno carbaboranes.

A vinylcarbenoid approach toward N-functionalization of NH-pyrazoles is presented. The rhodium(II)-catalyzed reaction of methyl styryl-diazoacetate ( 1 ) or dimethyl 2-diazoglutaconate ( 3 ) with 3,5-disubstituted pyrazoles gave products of carbenoid N–H insertion in high combined yields, although regioselectivity issues posed by the pyrazole or the vinylcarbenoid moiety as well as positional and configurational isomerism concerning the C,C double bond of the latter led to product mixtures. The ambident reactivity of the vinylcarbenoid derived from 1 could be steered by the catalyst: while Rh 2 (OAc) 4 yielded products of direct carbenoid insertion preferentially, silver(I) catalysis strongly favored reaction at the vinylogous site of the carbenoid resulting in an N-allylation of the pyrazoles.

The preparation, characterization and the molecular structure of a dinuclear uranyl complex [(UO 2 ) 2 L(OCMe 2 ) 2 ] supported by the bis-salophen ligand N , N ′, N ″, N ′″-tetra-(3,5-di- tert -butylsalicylidene)-1,2,4,5-phenylenetetraamine (L 4– ) is described. [(UO 2 ) 2 L(OCMe 2 ) 2 ] was prepared by reaction of uranyl nitrate with the neutral, protonated form of the ligand (H 4 L) in acetone. From a saturated acetone solution [(UO 2 ) 2 L(OCMe 2 ) 2 ]·1.5(OCMe 2 ) crystallizes triclinically, space group P 1̅ with a = 1522.7(2), b = 1751.4(2), c = 1815.4(2) Å, α = 109.16(1), β = 99.29(1), γ = 105.29(1)° and Z = 2. Each uranium atom is surrounded in a distorted pentagonal bipyramidal fashion by two O and two N atoms of the salicylidene units, one O atom of an acetone ligand, and the two oxo groups. The cyclic voltammogram of [(UO 2 ) 2 L(OCMe 2 ) 2 ] shows two quasi-reversible redox processes centered at +0.57 V and +0.82 V vs. Fc + /Fc attributed to the sequential oxidation of the coordinating phenolates to phenoxyl radicals. The crystal structure of an ethanol solvate of H 4 L was also determined by X-ray crystallography. H 4 L·5EtOH: triclinic, space group P 1̅, a = 1003.4(3), b = 1187.7(3), c = 1905.1(5) Å, α = 75.75(2), β = 78.74(2), γ = 66.66(2)°, Z = 1.

The complex Sn(II) fluorides A SnF 3 ( A = Na, K, Rb, Cs) were synthesized from the alkali fluorides and SnF 2 in methanol through a solvothermal route. Their 119 Sn Mössbauer spectra manifest divalent tin. The isomer shifts range from 3.09 to 2.94 mm s –1 . The pronounced lone-pair character at the Sn(II) centres is expressed by strong electric quadrupole splitting (1.91–1.95 mm s –1 ). The two, respectively four crystallographically independent tin sites in NaSnF 3 , KSnF 3 and RbSnF 3 could not be resolved in the 119 Sn spectra.