Insight into the Electron Density Distribution in an O,N-Heterocyclic Stannylene by High-Resolution X-ray Diffraction Analysis

In this paper we present the synthesis and results of a high-resolution single-crystal X-ray diffraction experiment on the O,N-heterocyclic stannylene (tBuAPSn) (1) containing the chelate ligand 4,6-di-tert-butyl-N-tert-butyl-o-amidophenolate. The experimental work is accompanied by a charge density study based on a topological analysis according to quantum theory of atoms in molecules (QTAIM) together with a NBO calculation of the crystal packing fragment containing a Sn-Sn bond. According to QTAIM, the Sn-Sn interaction is covalent ( backward difference (2)rho(r)<0, h(e)(r)<0). In the view of NBO analysis, there are two donor-acceptor bonding interactions between the tin atoms of adjacent molecules. The Sn-Sn bond energy evaluated by the Espinosa-Molins-Lecomte correlation is equal to - 9.1 kcal/mol. We carried out the investigation of source function not only in CP(3,-1) on the Sn-Sn bond but also on NCI-defined isosurface (lambda(2)<0). The source function shows that the electron density from the Sn basins extensively contributes to the formation of this Sn-Sn bond in 1.