Structural and phase transformations in the thiourea/zinc acetate system

Using differential thermal analysis and thermogravimetry, we have studied thermal decomposition of a mechanical mixture of thiourea and zinc acetate, resulting in the formation of a composite material consisting of graphitic carbon nitride and zinc acetate, g-C3N4/ZnS, and possibly containing zinc oxide (ZnO) inclusions. In the case of a mixture containing the stoichiometric sulfur:zinc ratio for zinc sulfide synthesis, one can obtain a material containing only ZnS semiconductor crystals embedded in a g-C3N4 matrix. ZnS is formed in the temperature range 317–367 °C as a result of decomposition of zinc complexes with thiourea. Heating the mixture to above 560 °C increases the rate of the thermal decomposition of g-C3N4, which reaches completion between 720 and 740 °C. The presence of oxygen in the reaction atmosphere also accelerates this process, without significantly changing the temperature range of synthesis or decomposition of reaction products. The proposed technique can be used for the synthesis of g-C3N4-based composite materials and other semiconducting metal sulfides

Indenyl Rhodium Complexes with Arene Ligands: Synthesis and Application for Reductive Amination

An efficient protocol for synthesis of indenyl rhodium complexes with arene ligands has been developed. The hexafluoroantimonate salts [(η⁵-indenyl)­Rh­(arene)]­(SbF₆)₂ (arene = benzene (<b>2a</b>), <i>o</i>-xylene (<b>2b</b>), mesitylene (<b>2c</b>), durene (<b>2d</b>), hexamethylbenzene (<b>2e</b>), and [2.2]­paracyclophane (<b>2g</b>)) were obtained by iodide abstraction from [(η⁵-indenyl)­RhI₂]_<i>n</i> (<b>1</b>) with AgSbF₆ in the presence of benzene and its derivatives. The procedure is also suitable for the synthesis of the dirhodium arene complex [(μ-η:η′-1,3-dimesitylpropane)­{Rh­(η⁵-indenyl)}₂]­(SbF₆)₄ (<b>3</b>) starting from 1,3-dimesitylpropane. The structures of [<b>2e</b>]­(SbF₆)₂, [<b>2g</b>]­(SbF₆)₂, and [<b>3</b>]­(SbF₆)₄ were determined by X-ray diffraction. The last species has a sterically unfavorable conformation, in which the bridgehead carbon atoms of the indenyl ligand are arranged close to the propane linker between two mesitylene moieties. Experimental and DFT calculation data revealed that the benzene ligand in <b>2a</b> is more labile than that in the related cyclopentadienyl complexes [(C₅R₅)­Rh­(C₆H₆)]²⁺. Complex <b>2c</b> effectively catalyzes the reductive amination reaction between aldehydes and primary (or secondary) amines in the presence of carbon monoxide, giving the corresponding secondary and tertiary amines in very high yields (80–99%). This protocol is the most active in water

Indenyl Rhodium Complexes with Arene Ligands: Synthesis and Application for Reductive Amination

An efficient protocol for synthesis of indenyl rhodium complexes with arene ligands has been developed. The hexafluoroantimonate salts [(η⁵-indenyl)­Rh­(arene)]­(SbF₆)₂ (arene = benzene (<b>2a</b>), <i>o</i>-xylene (<b>2b</b>), mesitylene (<b>2c</b>), durene (<b>2d</b>), hexamethylbenzene (<b>2e</b>), and [2.2]­paracyclophane (<b>2g</b>)) were obtained by iodide abstraction from [(η⁵-indenyl)­RhI₂]_<i>n</i> (<b>1</b>) with AgSbF₆ in the presence of benzene and its derivatives. The procedure is also suitable for the synthesis of the dirhodium arene complex [(μ-η:η′-1,3-dimesitylpropane)­{Rh­(η⁵-indenyl)}₂]­(SbF₆)₄ (<b>3</b>) starting from 1,3-dimesitylpropane. The structures of [<b>2e</b>]­(SbF₆)₂, [<b>2g</b>]­(SbF₆)₂, and [<b>3</b>]­(SbF₆)₄ were determined by X-ray diffraction. The last species has a sterically unfavorable conformation, in which the bridgehead carbon atoms of the indenyl ligand are arranged close to the propane linker between two mesitylene moieties. Experimental and DFT calculation data revealed that the benzene ligand in <b>2a</b> is more labile than that in the related cyclopentadienyl complexes [(C₅R₅)­Rh­(C₆H₆)]²⁺. Complex <b>2c</b> effectively catalyzes the reductive amination reaction between aldehydes and primary (or secondary) amines in the presence of carbon monoxide, giving the corresponding secondary and tertiary amines in very high yields (80–99%). This protocol is the most active in water