Band 80, Heft 3-4

Cadmium metal exhibits, in comparison with other metals, a low melting point of T = 594 K and exhibits a comparatively high vapor pressure. It therefore can be broadly used as a reactive flux medium for the growth of intermetallic phases. The results of phase-analytical investigations leading to new compounds, and of selected crystal growth experiments for direction dependent physical property studies are reviewed.

Solvochemical syntheses attempts to obtain fluoride oxidotungstates of yttrium and holmium yielded coarse single crystals of Y 2 WO 6 and Ho 2 WO 6 . Both compounds crystallize isotypically in the monoclinic space group C 2/ c ( a ≈ 1621, b ≈ 1100, c ≈ 535 pm; β ≈ 107.5°) with eight formula units per unit cell. The crystal structure contains three crystallographically distinguishable rare earth metal cations, which all exhibit a coordination number of eight in shapes between twisted tetragonal prisms and trigonal dodecahedra. The hexavalent tungsten cations are surrounded by five of the six crystallographically different oxide anions forming isolated, i.e. non -condensed, trigonal bipyramids that show a very strong distortion. The sixth oxygen atom is tetrahedrally coordinated by rare earth metal ( RE ) cations with the resulting [O RE 4 ] tetrahedra building up ∞ 1 { [ O R E 2 2 / 4 R E 3 2 / 2 ] 2.5 + } ${\infty }^{1}\left\{[\mathrm{O}{\left(RE2\right)}_{2/4}{{\left(RE3\right)}_{2/2}]}^{2.5+}\right\}$ bands along [001]. These bands are arranged according to a hexagonal rod packing with the ( RE 1) 3+ cations and the [WO 5 ] 4− anions being situated between them.

The stannide Li 4 Rh 3 Sn 5 was synthesized by induction-melting of the elements in a sealed tantalum ampoule. The sample was characterized by powder X-ray diffraction and the Li 4 Rh 3 Sn 5 structure was refined from single-crystal X-ray diffractometer data: new type, orthorhombic space group Pnnm , a  = 813.27(11), b  = 2,259.6(3), c  = 449.94(6) pm, wR 2 = 0.0486, 1577 F 2 values and 64 variables. The rhodium and tin atoms form a rigid covalently bonded three-dimensional [Rh 3 Sn 5 ] network with Rh–Sn distances ranging from 263 to 277 pm. Within this network, the tin atoms form two different substructures, i. e., angled Sn1–Sn4–Sn5 units and isolated Sn2 and Sn3 atoms. The lithium atoms fill cages within the [Rh 3 Sn 5 ] network. They have coordination numbers 11, 12 and 13. Based on their different 7 Li resonance shifts two groups of distinct local environments can be identified in an intensity ratio of 3:1, namely the 4 g Wyckoff sites Li1, Li2, and Li5, and the 2 c Wyckoff sites Li3 and Li4. The whole Li 4 Rh 3 Sn 5 structure can be described by condensation of the Li1@LiRh 4 Sn 6 , Li2@Li 2 Rh 4 Sn 6 , Li3@Li 2 Rh 4 Sn 6 , and Li4@Li 2 Rh 4 Sn 6 polyhedra, including the Li5 atoms which are within the Li1 coordination sphere. The 119 Sn Mössbauer spectrum of Li 4 Rh 3 Sn 5 shows a superposition of two sub-signals in a ratio of 60:40. The two sub-signals with similar isomer shift are discernable through their quadrupole splitting parameters: ∼1.93 mm s −1 for the tin atoms of the angled Sn 3 unit, and ∼1.20 mm s −1 for the isolated tin atoms with a more symmetric electron density distribution.

The Sc 5 Co 19 P 12 -type silicides RE 5 Ir 19 Si 12 ( RE  = Y, Gd–Dy, Er, Tm, Lu) were synthesized by arc-melting of the elements and subsequent annealing of the product samples at T  = 870 K for one week. The polycrystalline samples were characterized by powder X-ray diffraction. The structure of Tm 5 Ir 19 Si 12 was refined from single-crystal X-ray diffractometer data: hexagonal space group P 6‾2 m , a  = 1,269.70(4), c  = 393.17(1) pm, w R 2 = 0.0486, 847 F 2 values and 45 variables. The iridium and silicon atoms form a rigid covalently bonded three-dimensional [Ir 19 Si 12 ] substructure with Ir–Ir and Ir–Si distances ranging from 279 to 291 pm and 229–279 pm, respectively. The two crystallographically independent thulium atoms fill larger cavities within the [Ir 19 Si 12 ] substructure. They have coordination numbers of 16 and 15. The silicides RE 5 Ir 19 Si 12 belong to the large family of metal-rich structures with a ratio of metal to p -element of 2:1. The geometry of the structure can be explained by condensation of three different types of silicon-centered trigonal prisms built by the thulium and iridium atoms.

A solution, X-ray crystallographic and theoretical study, including Hirshfeld Surface analysis, of methoxy and hydroxy substituted ( E )- N ′-(benzylidene)-2-(thien-2-yl)acetohydrazides, has been carried out. The molecules have an ( E ) arrangement about the C=N bond, both in solution, while in the solid state, either a syn - or anti -NHCO arrangement is observed, depending on the substituents. Compounds having the syn -NHCO arrangement form symmetric cyclic R 2 2 ${R}_{2}^{2}$ (8) dimers, linked by pairs of N–H (hydrazinyl) ···O (carbonyl) hydrogen bonds, and columns of parallel and equally spaced layers of molecules, separated by short perpendicular distances, and with extensive overlap of the C(O)–NHN=CH-phenyl fragments. Compounds having anti -NHCO arrangements in the solid state, on the other hand, form molecular chains, also linked by strong N–H (hydrazinyl) ···O (carbonyl) hydrogen bonds, but instead of regular columns, the molecules form layered dimers arranged in an anti -parallel manner, with short perpendicular distances between the molecules and again, with considerable overlapping of the delocalised fragments of the molecules. Disorder arising from 180° flips of the thienyl ring is present in the crystal structures of the monosubstituted methoxy and for the hydroxy substituted compounds, while the dimethoxy compounds in the solid state have ordered structures. DFT calculations were carried out on the relative stability and ease of conversion of the thienyl orientations, and on the frontier orbitals. The Hirshfeld surface analyses confirmed the importance of the N–H (hydrazinyl) ···O (carbonyl) hydrogen bonds in forming the dimers for the syn -compounds and chains for the anti -NHCO compounds, and also the presence of π interactions.

In this study, we present the synthesis and characterization of three transition metal 1,5-naphthalenedisulfonates: [Ni(PTP)₂]·(1,5-NDS)·2H₂O ( 1 ), [Mn(PTP)(1,5-NDS)] ( 2 ), and [Zn(PTP)(1,5-NDS)(H₂O)] 2 ·2.5H₂O ( 3 ). Herein, PTP refers to 4′-phenyl-2,2′:6′,2″-terpyridine while 1,5-NDS denotes the naphthalene-1,5-disulfonate dianion. Compound 1 exhibits a structure in which the sulfonate groups of the 1,5-naphthalenedisulfonate anions are not engaged in coordination. In compound 2 , the Mn(II) ions are interconnected through 1,5-NDS anions to form chains along the c axis. Compound 3 features a chain structure via coordination interactions between the metal cations and the 1,5-naphthalenedisulfonate anions; adjacent chains are linked by hydrogen bonds to create a double-chain arrangement. Solid diffuse reflection spectra reveal that these compounds exhibit maximum absorption around 290 nm. The third-order nonlinear optical (NLO) properties of these complexes was investigated using the single-beam Z-scan techniques under laser irradiation at a wavelength of 532 nm. All three compounds demonstrate significant third-order nonlinear optical absorption effects with absorption coefficients of 1.85 × 10 −5  m W −1 for compound 1 , 1.12 × 10 −5  m W −1 for compound 2 and 1.73 × 10 −5  m W −1 for compound 3 . The corresponding calculated values for third-order NLO susceptibility χ ³ are 3.00 × 10⁻ 7  esu, 1.81 × 10⁻ 7  esu and 2.80 × 10⁻ 7  esu, respectively.

For the provision of clean water, and the prevention of toxic effects of organic pollutants, it is important to develop technologies for pollutant elimination and water remediation. This study presents the design of a high-performing photocatalyst under mild conditions, using aqueous solutions, without requiring thermal treatment. The catalyst comprised of phase-pure rutile-type Ni–TiO 2 nanocrystals, with substantially reduced bandgap ( E g  = 2.32 eV) at 0.92 at% doping of Ni 2+ in TiO 2 , prepared via coprecipitation of Ni 2+ and [TiCl 4 ] – at T  = 333 K. The Ni 2+ introduces p -type channels, and lowers the E g , thereby improving the photocatalytic elimination of methylene blue under natural sunlight. The analyses reveal a 255 % increase in photodegradation kinetics, with a rate constant of 3.72 × 10 −2 min −1 , at T  = 310 K.

The two trans -Ru VI complexes, (Ph 4 P) 2 [ trans -O 2 RuCl 4 ]·CH 2 Cl 2 ( 1 ) and [(Ph 3 P) 2 N] 2 [ trans -O 2 RuCl 4 ]·CH 2 Cl 2 ( 2 ), were obtained in high yields by direct oxidation of RuCl 3 ·3H 2 O with NaIO 4 , followed by treatment with KOH and cation exchange reactions. The crystal structures of the two complexes were determined by single crystal X-ray diffraction. Complexes 1 and 2 both crystallize in the triclinic space groups P 1 ‾ $\overline{1}$ , with a  = 9.9766(16), b  = 11.0566(18), c  = 12.566(2) Å, α  = 69.354(2), β  = 77.228(2), γ  = 82.328(2)°, Z  = 1 for complex 1 and a  = 10.897(3), b  = 12.402(4), c  = 14.449(5) Å, α  = 110.395(4), β  = 91.853(4), γ  = 98.500(4)°, Z  = 1 for complex 2 . The two complexes were characterized by FT-IR, 1 H NMR, 31 P{H} NMR, and UV/Visible spectroscopies, and their electrochemical properties were also investigated.