Showing papers by "Louis J. Farrugia published in 2011"
TL;DR: The quantum theory of atoms in molecules (QTAIM) was used to investigate the extent of π-delocalization in the thioamide side-chain, which is virtually coplanar with the benzene ring, but the topological evidence and the atomic graphs of the oxygen atoms did not provide convincing evidence forπ-Delocalization involving the methoxy substituents.
Abstract: The charge density in 2,5-dimethoxybenzaldehyde thiosemicarbazone (1) has been studied experimentally using Mo-Kα X-ray diffraction at 100 K, and by theory using DFT calculations at the B3LYP/6-311++G(2d,2p) level. The quantum theory of atoms in molecules (QTAIM) was used to investigate the extent of π-delocalization in the thioamide side-chain, which is virtually coplanar with the benzene ring. The experimental and theoretical ellipticity profiles along the bond paths were in excellent agreement, and showed that some of the formal single bonds in the side-chain have significant π-bond character. This view was supported by the magnitudes of the topological bond orders and by the delocalization indices δ(ΩA, ΩB). An orbital decomposition of δ(ΩA, ΩB) demonstrated that there was significant π-character in all the interchain non-H chemical bonds. On the other hand, the source function referenced at the interchain bond critical points could not provide any evidence for π-delocalization, showing instead only l...
18 citations
01 Jan 2011
TL;DR: In this article, the authors focus on the use of a broad spectrum of QTAIM indicators in the context of interpreting the nature of chemical bonding and chemical reactivity in main group and transition metal compounds, including the classical bond critical point indicators ρ b and ∇ 2 ρb, as well as ones which are less dependent on local properties, such as the Valence Shell Charge Concentrations (VSCCs), the profiles of bond ellipticities e along the bond path, the delocalisation indices δ between atomic basins and the source function.
Abstract: This chapter focuses on the use of a broad spectrum of QTAIM indicators in the context of interpreting the nature of chemical bonding and chemical reactivity in main group and transition metal compounds. These indicators include the classical bond critical point indicators ρ b and ∇2 ρ b, as well as ones which are less dependent on local properties, such as the Valence Shell Charge Concentrations (VSCCs) on individual atoms, the profiles of bond ellipticities e along the bond path, the delocalisation indices δ between atomic basins and the source function. In the main, the chosen examples come from very recent work and have been selected to illustrate the use of the QTAIM indicators in providing a full picture of the chemical bonding and, where appropriate the reactivity.