Sulfuric Acid Solutions of [Pt(OH)(HO)]: A Platinum Speciation Survey and Hydrated Pt(IV) Oxide Formation for Practical Use.

The systematic study of the platinum speciation in sulfuric acid solutions of platinum (IV) hydroxide {[Pt(OH)(HO)], HHPA} was performed with the use of a combination of methods. Depending on the prevailing Pt form, the three regions of HSO concentration were marked: (1) up to 3 M HSO forms unstable solutions gradually generating the PtO·HO particles; (2) 4-12 M HSO, where the series of mononuclear aqua-sulfato complexes ([Pt(SO)(HO)], where = 0···4) dominate; and (3) 12 M and above, where, along with [Pt(SO)(HO)] species, the polynuclear Pt(IV) species and complexes with a bidentate coordination mode of the sulfato ligand are formed. For the first time, the salts of the aqua-hydroxo Pt(IV) cation [Pt(OH)(HO)]SO (triclinic and monoclinic phases) were isolated and studied with a combination of methods, including the single-crystal X-ray diffraction.

Keggin-type polyoxometalate 1 : 1 complexes of Pb(II) and Bi(III): experimental, theoretical and luminescence studies.

Bi3+ and Pb2+ uptake by a monolacunary Keggin-type [PW11O39]7- anion leads to the formation of [PW11O39Bi]4- and [PW11O39Pb]5- complexes with a stereochemically active lone pair at the incorporated heterometal. The two complexes were isolated as (TBA)4[PW11O39Bi] (1) and (TBA)5[PW11O39Pb] (2) and characterized by 31P and 183W NMR spectroscopy, high-resolution electrospray mass-spectrometry (HR-ESI-MS) and cyclic voltammetry (CV). EXAFS and XANES data confirm the unchanged oxidation state and ψ-square pyramidal geometry of Bi3+ and Pb2+ in 1 and 2.

Photoinduced Deposition of Platinum from (BuN)[Pt(NO)] for a Low Pt-Loading Pt/TiO Hydrogen Photogeneration Catalyst.

An efficient method for the deposition of ionic platinum species PtO onto a TiO surface was developed on the basis of light-induced activation of the [Pt(NO)] anion. The deposited PtO species with an effective Pt oxidation state between +4 and +2 have an oxygen-made environment and include single ion centers {PtO} and polyatomic ensembles {PtO} connected to a TiO surface with Pt-O-Ti bonds. The resulting PtO/TiO materials were tested as photocatalysts for the hydrogen evolution reaction (HER) from a water ethanol mixture and have shown uniquely high activity with the rate of H evolution achieving 11 mol h per gram of Pt, which is the highest result for such materials reported to date.

Insight into the thermal decomposition of ammonium hexahalogenoiridates(IV) and hexachloroiridate(III).

Thermal decomposition of (NH4)3[IrCl6]·H2O, (NH4)2[IrCl6] and (NH4)2[IrBr6] in reductive and inert atmospheres has been investigated in situ using quick-EXAFS and temperature-resolved powder X-ray diffraction. For the first time, (NH4)2[Ir(NH3)Cl5] and (NH4)2[Ir(NH3)Br5] have been proven as intermediates of thermal decomposition of (NH4)3[IrCl6]·H2O, (NH4)2[IrCl6] and (NH4)2[IrBr6]. Thermal degradation of (NH4)2[IrCl6] and (NH4)2[IrBr6] is a more complex process as suggested previously and includes simultaneous formation of (NH4)2[Ir(NH3)Cl5] and (NH4)2[Ir(NH3)Br5] intermediates mixed with metallic iridium.

Thermal decomposition of ammonium hexachloroosmate.

Structural changes of (NH)[OsCl] occurring during thermal decomposition in a reduction atmosphere have been studied in situ using combined energy-dispersive X-ray absorption spectroscopy (ED-XAFS) and powder X-ray diffraction (PXRD). According to PXRD, (NH)[OsCl] transforms directly to metallic Os without the formation of any crystalline intermediates but through a plateau where no reactions occur. XANES and EXAFS data by means of Multivariate Curve Resolution (MCR) analysis show that thermal decomposition occurs with the formation of an amorphous intermediate {OsCl} with a possible polymeric structure.