Borowce jako centra kwasów Lewisa w oddziaływaniach międzycząsteczkowych : porównanie z wiązaniami wodorowymi
Journal Title: Wiadomości Chemiczne - Year 2017, Vol 71, Issue 7
Abstract
The triel bonds are analyzed and compared with the hydrogen bond interaction. The triel bonds belong to the class of interactions that are named as the σ-hole and π-hole bonds. The σ-hole bond is an interaction between the σ-hole characterized by the positive electrostatic potential and the electron rich regions such as lone electron pairs, π-electron systems, in other words, centers paying a role of Lewis bases. The σ-holes may be observed for elements of the 14–18 groups of the periodic system and the corresponding interactions with Lewis bases are named; tetrel, pnicogen, chalcogen, halogen and aerogen bonds, respectively. On the other hand, π-holes also characterized by the positive electrostatic potential are observed for centers in planar molecules or planar fragments of molecules in regions above those planes. π-holes may be attributed to triel centers (13th group of the periodic system). The boron and aluminium trihydrides and trihalides are examples of molecules where triels are characterized by π-holes. The mechanism of the triel bond formation is very similar to the mechanism of the formation of the hydrogen bond. It is the Lewis acid – Lewis base interaction where the electron charge transfer from the base unit to the acid one is observed. Next there is outflow of the electron charge from the triel center to the other parts of the Lewis acid unit; in other words the positive charge of the triel center increases as a result of complexation. The triel bonds are often very strong and often they possess characteristics of typical covalent bonds; this is confirmed by the QTAIM (Quantum Theory of Atoms in Molecules) and NBO (Natural Bond Orbital) approaches. For example, for the triel bonds the bond paths between the triel center and the Lewis base center are observed with the bond critical points (BCPs) attributed to those paths. Similarly for the A-H…B hydrogen bonds the H…B bond paths are observed. The parameters of those BCPs often indicate the covalent character of the triel bonds and analogously those characteristics for H-bonds may also indicate the covalent character of the latter interactions. It is very interesting that the triel bonds are observed experimentally in the real systems; for example in crystal structures. The triel center which is trivalent and possesses the trigonal configuration is hypovalent; it means that the octet rule is not obeyed here because of the valence electrons´ deficiency (the triel center possesses six valence electrons in such species). Thus it may interact with one Lewis base ligand reaching rather stable octet and tetrahedral configuration. If the trivalent triel center interacts with two Lewis base ligands thus it may lead to the configuration of the trigonal bipyramid with the hypervalent and pentavalent triel center. These kinds of the triel species occur in crystal structures that are described here.
Authors and Affiliations
Sławomir Janusz Grabowski
Keywords
Related Articles
- EP ID EP569849
- DOI -
- Views 132
- Downloads 0
Jędrzej Śniadecki i ruten
brak
Wpływ montmorylonitu na właściwości reologiczne wodnych dyspersji karboksymetyloskrobi
Water dispersions are usually a colloidal system in which one of the phases is highly dispersed in a second of a continuous nature, called a dispersion medium (in this case it is water). Dispersal is also called the proc...
Projekt Avogadro (IAC) i redefinicja jednostki liczności materii
The paper presents the International Avogadro Coordination (IAC ) and the problem of redefinition of the unit of amount of substance (the mole) in the context of a comprehensive reform of the international system of unit...
Nowe technologie on-line w dydaktyce chemii
The development of on-line technologies in the last years provided us with a possibility for the efficient video teaching in e- or blended- chemistry learning [1–10]. In this publication we reviewed materials which are a...
Biomateriały stosowane w inżynierii komórkowej i medycynie regeneracyjnej
Tissue engineering is a very rapidly developing domain of science. There is a huge interest in the biology of stem cells, especially in their proliferation, differentiation and spreading in the response to different fact...