GENERAL ASPECTS OF THE CHEMISTRY OF DITHIOCARBAMATES, THEIR METALLIC COMPLEXES AND THEIR INTERACTIONS WITH IMPORTANTE ENZYMES – A BRIEF REVISION. Dithiocarbamates (DTCs) comprise a series of compounds included in the class of 1,1`dithiolates. The application of these organic molecules in the coordination chemistry of some metals is well explored in the last decades, along with their potential applications in medicinal chemistry. In view of our expertise in this field, the syntheses of new DTCS, their coordination chemistry towards various metallic cations and their biocide activities, we summarize in this manuscript the outcomes of some investigations registered in the literature, involving the interactions of DTCs or their complexes with some key enzymes such as carbonic anhydrases, superoxide dismutase, urease, tyrosinase, glutathione, caspases and dehydrogenases. It is provided with a brief introduction of the chemistry of DTCs, electrochemistry, the kinetics of formation, solubility and stability towards solvation. The next topics summarize the results of some experiments concerning the inhibition of these cited enzymes effected by DTCs and some of their coordination complexes. The final remarks and conclusion of the outcomes are provided at the end of the manuscript.

ORGANOMETALLIC COMPOUNDS OF TIN(II) - SOME MAIN GROUP METAL STANNYLS. This paper aims to summarise some chemical information about selected main group metal stannyl compounds. The number of these compounds in the literature are much fewer than those with transition metal cations. Most papers report details of stannyls containing Li(I), Na(I) and K(I), such as synthetic routes, spectroscopic results and their molecular structures. This review comprises not only information of stannyls containing these cations, but also some alkaline-earth species containing Mg(II), Ca(II), Sr(II), Ba(II), as well as Sn(II). In some compounds, the alkaline or alkaline earth cation is connected to the stannyl fragment through a Sn – M bond, evidenced by X-ray crystallographic data or by solution- or solid-state 119Sn NMR experiments. The introduction part of the paper summarizes the chemical aspects of these compounds and their importance in the organometallic chemistry of Sn(II) as a research area. The second part of this review is dedicated to a broad discussion of the syntheses and structural aspects of some Li(I), Na(I) and K(I) derivatives. The structure of some stannyl compounds of Mg(II), Ca(II), Sr(II), Ba(II) are displayed in the third part of this paper. Two rare examples of Sn(II)-based stannyl derivatives are shown in the final part of the review. This review also highlights how important it is to correlate X-ray crystallographic data with those obtained by solution- or solid-state 119Sn-NMR experiments in order to determine the degree of covalence in the Sn – M bond.

The slow process of the discovery of the elements led to a need to investigate their relations with one another; this was the path, which ultimately produced Mendeleev’s classification, the ancestor of the present Periodic Table. Once established, the Table, in its turn, became a guiding thread leading to the discovery of yet other new elements. This whole process can be likened to a two-way avenue, the first way leading to the establishment of the classification, whereas the latter, once established, inverted the traffic, completing our present 118-element Periodic Table. In this sesquicentennial year of its inception, it is appropriate to survey the fascinating history of the long and arduous path of the creation of what can be rightly called the most concise encyclopedia devised by the human mind.

Tin chemistry sometimes is considered boring, colourless and with irrelevant applications. Archaeological, historical and technological facts show otherwise. These facts demonstrate that tin became vital for man in a distant past and its importance lasts thereafter. In this paper, it is introduced some historical arguments that reveal the significance of tin or cassiterite as strategic materials in ancient tools, beginning from the Bronze Age. This paper shows as well the importance of this metal in current times. It also describes the importance of Brazil in this scenario, given the large reserves of cassiterite and its crucial participation in the world market. In addition, it provides a revision of the main classes of tin compounds {Sn (IV) and Sn (II), among other oxidation states}. Additionally, it summarises some main applications of tin compounds, such as PVC stabilizers, antifouling paint and in the manufacturing of foams and polymers, discussing its strategic role in modern technologies. Finally, it highlights the importance of tin in the preparation of Nb3Sn, a superconducting alloy with niobium, and in the synthesis of new materials, for example, a two-dimensional polymer, structurally similar to graphene.

This article provides a short review of the chemistry of stannylenes and their derivatives, including the preparation, spectroscopic properties, molecular structure and reactivity of the various species. The organometallic chemistry of Sn(II) is far less explored than that of its much more common Sn(IV) counterpart. Organometallics of main group metals have become increasingly important in recent years, which prompted us to present an overview of the situation regarding the case of Sn(II).

This paper provides a brief review of the chemistry of cyclopentadienyl Sn(II) derivatives which includes the preparation, the molecular structure and reactivity associated with such bis-sandwich tin(II) species. It is compared structural and spectroscopic results and it is also discussed how the nature of the cyclopentadienyl ring bonded to the Sn centre plays an important role in the structural and stability features of the derivatives. Bulk rings such as C5HPr i4- , C5Bz5-, C5Me4SiMe2Bu t- and C5Ph5- render air-stable and parallel ring-bonded compounds.