Volume 39, Issue 3

In this review, we classify and analyze the structural data of more than 80 monomeric platinum coordination complexes with an inner coordination sphere of PtP 4 in which only organophosphines are involved. On the basis of the coordination mode of respective organophosphines, these complexes can be divided into six subgroups: Pt(PL) 4 , Pt(PL) 2 (PL′) 2 , Pt(η 2 -P 2 L)(PL) 2 , Pt(η 2 -P 2 L) 2 , Pt(η 2 -P 2 L)(η 2 -P 2 L′) 2 , and Pt(η 4 -P 4 L). The chelating ligands forming wide varieties of metallocycles: (P=P), (PNP), (PCP), (PC 2 P), (PP 2 P), (PC 2 NP), (PNCNP), (PNPNP), (POHOP), (POBOP), (PCNCP), (PC 3 P), (PC 4 P), and (PC 2 OC 2 P). The effects of both steric and electronic factors reflect on the values of P-Pt-P chelate angles. The total mean values of Pt-P elongate in the order: 2.289 Å (tetradentate)<2.306 Å (monodentate)<2.320 Å (bidentate). The same order shows the respective covalent bond weaknesses.

The data concerning the formulation of the Periodic Law and certain graphic variants of its interpretation, proposed at different times for 150 years from the moment of the opening of this law, have been presented and discussed. It was stated that, despite the presence of a very significant (several hundred) number of these variants, only two tabular versions of the Periodic Table of chemical elements, namely, the so-called “short-periodic” proposed by Dmitri Mendeleev and the so-called “long-periodic” proposed by Alfred Werner (which was recommended in the fullness of time by the International Union of Pure and Applied Chemistry), received practical applications. A modification of the indicated tabular variants, aimed at overcoming their shortcomings, has been proposed. The question of the existence of the upper boundary of the Periodic System and the probable prospects for obtaining super-heavy elements with a nuclear charge of Z  > 110, in particular a new category of them – 5 g -elements, has been also discussed.

The present review focuses on a comparison and assessment of zeolite catalyst performance of dimethyl ether and light olefin production through methanol. Dimethyl ether is a clean fuel which needs diverse processes to be produced. Methanol to dimethyl ether is a very novel process which offers considerable advantages versus additional processes for the production of dimethyl ether. The corresponding fixed-bed reactors compose the most important section of such a process. Production of dimethyl ether by the mentioned process is of high importance since it can be catalytically transferred to a substance with the value of propylene. Furthermore, in case of capability to transfer low-purity methanol into dimethyl ether, less expensive methanol can be consequently achieved with higher value added. In the petrochemical industry, light olefins, for example, ethylene and propylene, can be used as raw materials for the production of polyolefin. The present review aims to produce dimethyl ether in order to reach olefin substances, initially conducting a compressive assessment on production methods of olefin substances.