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Molecular Design of Neutral Intramolecular Complexes Bearing Two Silicon Atoms Anchored by a Carbonyl Oxygen Atom: N , N ′‐Bis(silylmethyl)propylene Ureas
Author(s) -
Sidorkin Valery F.,
Belogolova Elena F.,
Pestunovich Vadim A.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500498
Subject(s) - electronegativity , intramolecular force , tetracoordinate , chemistry , atom (system on chip) , crystallography , silicon , molecule , oxygen atom , covalent bond , stereochemistry , organic chemistry , computer graphics (images) , computer science , planar , embedded system
B3LYP and MP2 computations have been performed on a variety of Si , Si ′‐substituted N , N′ ‐bis(silylmethyl)propylene ureas. According to electron‐density atoms‐in‐molecules (AIM) and electron localization function (ELF) quantum‐topological analyses, a transition from the unstable non‐chelate forms of these compounds to mono‐ and bis‐chelate forms results in the successive interaction of one and two tetracoordinate silicon atoms with the carbonyl oxygen and the formation, respectively, of one and two covalent, polar Si⋅⋅⋅O bonds. This previously unknown XSi←O→SiX type of bonding in isomers possessing an anchor structure may be classified as a five‐center, six‐electron (5c‐6e) bond. The factors that favor the existence of Si , Si ′‐substituted N , N′ ‐bis(silylmethyl)propylene ureas exclusively in the form of stable, bridged complexes (the size of equatorial ligands and the electronegativity of axial substituents at the silicon atom, change in the donor capability of the carbonyl group, and effect of the polar solvent) are discussed.