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New complex manganese vanadate materials were synthesized as high-quality single crystals in multi-millimeter lengths using a high-temperature, high-pressure hydrothermal method. One compound, Mn5(VO4)2(OH)4, was grown from Mn2O3 and V2O5 in 3 M CsOH at 580 °C and 1.5 kbar. Changing the mineralizer to 1 M CsOH/3MCsCl leads to the formation of another product, Mn6O(VO4)2(OH). Both compounds were structurally characterized by single-crystal X-ray diffraction (Mn5(VO4)2(OH)4: C2/m, Z = 2, a = 9.6568(9) A, b = 9.5627(9) A, c = 5.4139(6) A, β = 98.529(8)°; Mn6O(VO4)2(OH): P21/m, Z = 2, a = 8.9363(12) A, b = 6.4678(8) A, c = 10.4478(13) A, β = 99.798(3)°), revealing interesting low-dimensional transition-metal features. Mn5(VO4)2(OH)4 possesses complex honeycomb-type Mn–O layers, built from edge-sharing [MnO6] octahedra in the bc plane, with bridging vanadate groups connecting these layers along the a-axis. Mn6O(VO4)2(OH) presents a more complicated structure with both octahedral [MnO6] and trigonal bipyramidal...

High quality single crystals with sizes up to 2—3 mm/edge of the transition metal vanadates (Va—g) are hydrothermally prepared and their structures are determined by single crystal XRD.

A series of new lanthanide (Ln) silicates have been synthesized using high temperature hydrothermal techniques, and structurally characterized using single crystal and powder X-ray diffraction. The compounds have the general formula NaBa3Ln3Si6O20 (Ln = Y, Nd, Sm, Eu, Gd), and crystallize in the space group Ama2 (No.40). As a representative example, the unit cell parameters of NaBa3Gd3Si6O20 are a = 14.731(3) A, b = 23.864(5) A, c = 5.5449(11) A and Z = 4. The title compounds adopt a three dimensional polar acentric framework made of Ln–O–Si bonding. The framework is comprised of LnO8 and LnO7 units forming edge-sharing infinite chains along the c-axis. These oxy-bridged infinite chains are also linked by [Si4O13] tetrasilicate and [Si2O7] disilicate units to form the three-dimensional framework structure, with Ba2+ and Na+ cations residing inside channels of the framework. The polarity in the structure is imparted by the unusual tetrasilicate arrangement. The luminescence and magnetic properties were investigated on selected compounds. The temperature dependent magnetic susceptibility measurements on the Nd, Sm, and Gd derivatives reveal a Curie–Weiss behavior with an antiferromagnetic coupling parameter. For the Eu-derivative, the temperature dependent magnetic susceptibility deviates significantly from Curie–Weiss behavior. Luminescence properties of NaBa3Eu3Si6O20 and NaBa3Sm3Si6O20 compounds exhibited the characteristic transitions of Eu3+ (5D0 → 7FJ, J = 0–4) and Sm3+ (4G5/2 → 6HJ, J = 5/2, 7/2), respectively, leading to strong visible red and orange emissions, respectively.

Large single crystals of Ba2V(VO4)2(OH) (I) and Sr2V(VO4)2(OH) (II) are hydrothermally synthesized from mixtures of BaO or SrO, V2O3, V2O5, and aqueous NaOH as a mineralizer solution (Ag ampules, autoclave, 1.2 kbar, 650 °C, 10 d).

The series of non-centrosymmetric crystals (VIII)—(X) is hydrothermally prepared from precursor barium borosilicate glasses (IV) and (VI) and characterized by single crystal XRD.

Single crystals of LiKTmF 5 were grown hydrothermally. Its crystal structure was studied with single-crystal X-ray diffraction to 8.6 GPa. The material is monoclinic (P2 1 /c, Z = 4) and does not undergo any phase transition in the pressure range studied here. The analysis of its pseudosymmetry with respect to the minimal k -supergroup C2/m reveals that the deviations of the individual atoms from the respective higher symmetrical positions in C2/m are increasing on compression, i.e., due to the reduction of the unit-cell volume. Such a behaviour is the opposite of the effect of incorporation of various M cations in the LiKMF 5 materials (M:Y and rare earths) at atmospheric conditions, since LiKYbF 5 and LiKLuF 5 with the smallest unit cells crystallize in space group C2/m, while LiLYF 5 with a larger unit cell has P2 1 /c symmetry.

Single crystals of CsCeF3 are prepared hydrothermally from a 1:5 molar mixture of CeF4 and CsF (autoclave, 250 °C, 1 d).

Single crystals of the title compounds are hydrothermally prepared from aqueous mixtures of ThF4 or CeF4 and LiF (autoclave, 225 °C, 1 d).

Ba11B26O44(PO4)2 (OH)6 (I) is prepared in low yield by hydrothermal reaction of Ba(OH)2, (NH4)2B10O16, and BaHPO4 in aq.

Single crystals of K2ThF6 (I) and K7Th6F31 (II) are prepared hydrothermally from a mixture of ThF4, KF, and KHF2 (Ag ampoules, autoclave, 575 °C, 3 d).

The crystal structures of the new compounds (V) and (VII) are determined by single crystal XRD.

The alkali hafnium fluorides Li2HfF6 (I), Na5Hf2F13 (II), K2Hf3OF12 (III), K3HfOF5 (IV), and (NH4)3HfOF5 (V) are hydrothermally prepared from aqueous solutions of HfF4, LiF, NaF, KF, KHF2, RbF, or CsF (sealed Ag ampule, autoclave, 400—600 °C, several days).

The title compounds are hydrothermally synthesized from aqueous mixtures of LnVO4 (Ln: Y, Sc, Dy, Ho, Lu, Tm, Yb) and K2CO3 (autoclave, 560 °C, 6 d).

The crystal structures of the new silicate fluorides (IV), (VI), and (VII) are determined by single crystal XRD.

Three new polymorphs of CsThF5 are hydrothermally synthesized from ThF4 and aqueous CsF solutions of varying concentrations in a silver ampule (autoclave, 575 °C, 2—12 d).

Sr3B6O11(OH)2 (I) is synthesized by solid state reaction of LiOH, B2O3, Sr(OH)2, and KOH (Pt crucible, 900 °C in air, 16 h) followed by reaction of the obtained product with aqueous SrCl2 solution (autoclave, 560 °C, 6 d, 90% yield).

Crystals of the new title compounds are synthesized by solid state reactions of MF2 (M: Sr, Ba), H3BO3, and NH4F (Pt crucible, 800 °C, 24 h) followed by hydrothermal reaction of the obtained powders with aqueous solutions of KF (for M: Sr) or KHF2 (for M: Ba) at 540 °C (welded silver ampules, 7 d).

New hydrated rare earth vanadates and rare earth oxy-vanadates are characterized by powder and single crystal XRD, and UV/VIS spectroscopy.

The new compounds (III) and (V)—(VII) are structurally characterized using powder and single crystal XRD.

Three novel hydrated borates Ba2B5O9(OH) (1), Sr2B5O9(OH) (2) and Li2Sr8B22O41(OH)2 (3) have been synthesized hydrothermally and their structures determined. Compounds (1) and (2) are isostructural, crystallizing in space group P21/c and having lattice parameters of a=6.6330(13) A, b=8.6250(17) A, c=14.680(3) A, β=93.46(3)° and a=6.4970(13) A, b=8.4180(17) A, c=14.177(3) A, β=94.35(3)°, respectively. Compound (3) crystallizes in P-1 with lattice parameters of a=6.4684(13) A, b=8.4513(17) A, c=14.881(3) A, α=101.21(3)°, β=93.96(3)°, γ=90.67(3)°. While similar in their axis lengths, (3) differs greatly in structure and formulation from (1) and (2). The structure of (1) and (2) is contrasted to that of the well-known mineral hilgardite (Ca2B5O9Cl·H2O).

The title compounds are synthesized hydrothermally under supercritical conditions from aqueous solutions of B2O3, Sr(OH)2 or Ba(OH)2, and BeO using NaOH as mineralizer (autoclave, 565 °C, 5 d, about 5% yield).

Crystals of Ba2TiSi2O8, Sr2TiSi2O8 (about 10% yield), Ba2VSi2O8, and Ba2TiGe2O8 belonging to the fresnoite family are hydrothermally prepared from aqueous solutions of Ba(OH)2 or Sr(OH)2, TiO2 or VO2, SiO2 or GeO2, and CsOH or KOH (silver ampules, autoclave, 500 °C, 5 d).

KNbO3 (I), KTaO3 (II), and KTa0.56Nb0.44O3 (III) are prepared by solid state reactions of appropriate mixtures of K2CO3 and Ta2O5 and/or Nb2O5 (950 °C, 72 h).

This article focuses on the chemistry of heavy polychalcogenides as ligands to transition metal centers. After reviewing some of the general synthetic strategies leading to metal polyselenides and polytellurides, work from the author's labs is discussed, which involves the coordination of polychalcogenide anions to metal carbonyls. It has been found that coordination of polychalcogenide anions to metal carbonyls often results in oxidation of the metal center, with loss of some or all of the carbonyl ligands. This oxidative decarbonylation reaction provides a convenient entry to a wide variety of new and existing metal chalcogenide complexes. The scope and potential of this unusual reaction is discussed.

As4Se4 and As4Se3 do not retain their solid-state structures in solution. Dissolution of As4Se4 in en/DMF (en = ethylenediamine, DMF = dimethylformamide) causes the cleavage of an AsAs bond and the formation of the As4Se62− anion. In the presence of excess polyselenide ions the remaining AsAs bond also breaks and the As2Se62− anion is produced. Reduction of As4Se4 by potassium in DMF in the presence of PPH4Cl also produces the As4Se62− anion. [PPh4]2[As4Se6] crystallizes (− 120°C) in the orthorhombic space group Pbca with cell dimensions a = 11.272(1), b = 19.817(2), c = 43.958(9) A, Z = 8. The As4Se62− anion resembles a basket with AsSe exocyclic bonds being the handles. [PPh4]2[As2Se6] crystallizes in the monoclinic space group P21/n with cell constants a = 10.817(2), b = 13.690(4), c = 16.298(3) A, β = 93.96(2)°, Z = 2. The As2Se62− ion has an As2Se4 ring in a trans-chair conformation with a terminal selenium atom on each arsenic atom.

Two new anionic antimony sulfide clusters [Sb6S6]2– and [Sb4S6]2– have been prepared and structurally characterized from the reduction of Sb2S5 with BH4– and [FeH(CO)4]– respectively.

Synthetic efforts utilizing Cs2CO3, Ag, M2S3 (M = As, Sb), and S8 in supercritical ammonia (160 °C) have yielded four novel, one-dimensional compounds in the Cs−Ag−M−S system. These members were ch...

A new form of polyheptatellurium dication, {[Te7][AsF6]2}∞, has been synthesized at room temperature and structurally characterized by single-crystal X-ray crystallography. The new infinite polymeric chain consists of six-membered rings bridged through a tellurium atom. Its structure is discussed and compared to those of other tellurium cation systems, including another polyheptatellurium dication, {[Te7][WOBr5]2}∞, and the previously reported “{[Te6][AsF6]2”.

A variety of Diels-Alder reactions have been performed in supercritical water as a reaction medium. The rapid reaction of Diels-Alder reactions of cyclopentadiene and various electron poor dienophiles such as diethyl fumarate and acrylonitrile is observed in supercritical water, and leads to high yields of clean products without added catalysts.

A new pseudoternary phase, Cs5Sb8S18(HCO3), was prepared from supercritical ammonia at 160 °C over 4 days using stoichiometric quantities of Cs2CO3, Sb2S3, and S8. Red parallelepipeds of the title phase crystallize in the centrosymmetric monoclinic space group C2/c, with a = 27.064(3) A, b = 11.634(4) A, c = 12.642(3) A, β = 97.45(2)°, and Z = 4. The compound has a layered structure, with the layers formed from ribbons of condensed ψ-SbS4 trigonal bipyramids linked via S32- chains, and both Cs+ and HCO3- ions between the layers, giving rise to the formula Cs5Sb8S12(S3)2(HCO3). Each layer is approximately 10 A thick, with two layers per unit cell. The condensation of the group 15/16 building blocks into ribbons is the result of a combination of edge- and vertex-shared antimony(III) sulfide pseudo trigonal bipyramids. In this phase, the S3 chains always link adjacent ribbons via apical coordination sites on the antimony atoms. The open cavities created by the linking trisulfide dianions between neighboring ...

Allylic alcohols are epoxidized with tert-butyl hydroperoxide in the presence of a vanadyl salen oxo-transfer catalyst in supercritical CO2. The metal catalyst was prepared in a simple two step, Schiff base reaction to form the salen ligand, followed by complexation to the vanadyl group. The epoxidation reactions are clean and give both high yields and good diastereoselectivity.

The compound diiron diphosphate dihydrate, Fe2P2O7(H2O)2, was synthesized hydro­thermally and crystallizes in the monoclinic space group P21/n. The compound has a somewhat open framework made up of edge-sharing iron(II) octahedra that form chains connected by five bridging diphosphates. The remaining octahedral site of each iron is occupied by coordinated water. The H atoms of the water molecules all point into a common channel.

The title compound, calcium dimanganese tetraoxide, CaMn2O4, was synthesized hydro­thermally and is made up of edge-sharing Mn3+ distorted octahedral layers and eight-coordinate Ca2+ centered polyhedral layers.

The ternary selenide Pb6Sb6Se17 was synthesized hydrothermally from the binaries (PbSe and Sb2Se3) and crystallizes in the orthorhombic space group Pbam (a = 15.835(3), b = 24.043(5), c = 4.134(2)A, Z = 2). The main building blocks of the crystal structure are ribbons made of square pyramidal [(Pb,Sb)Se5] groups running along [010].