Direct structural evidence for weak charge-transfer bonds in solids containing chemically saturated molecules

Hassel, O.; Rømming, Chr.

doi:10.1039/qr9621600001

Cited by 239 publications

(109 citation statements)

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“…in the mirror plane; the intermolecular S ... C1 distance, 3.41 A, is 0.24 A shorter than the sum, 3.65 A, of the van der Waals radii for sulphur and chlorine. As in other compounds where a similar intermolecular configuration with short intermolecular distances is observed (Hassel & Romming, 1962), the short S. • • C1 distance may be explained by charge transfer. The sulphur atom of the longer S-C1 bond has strong interaction with a nitrogen atom of a neighbouring molecule; the S. • • N distance, 3.01 A, is 0.34 A shorter than the sum of the van der Waals radii for nitrogen and sulphur.…”

Section: Determination Of the Structurementioning

confidence: 89%

The crystal structures of two sulphur-nitrogen compounds with (S–N)₃rings. II. Trithiazylchloride, (NSCl)₃, at –130°C

Wiegers¹,

Vos²

1966

Acta Cryst

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Section: Determination Of the Structurementioning

confidence: 89%

The crystal structures of two sulphur-nitrogen compounds with (S–N)₃rings. II. Trithiazylchloride, (NSCl)₃, at –130°C

Wiegers¹,

Vos²

1966

Acta Cryst

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“…The intermolecular O(1)...I distance is found to be 2.580 (6)A which is much shorter than the O...I van der Waals sum of 3.50A. Such O...halogen interactions have been observed in many other structures and have been analyzed in some detail (see Hassel & Romming, 1962, 1967Leser & Rabinovich, 1978;Cody & Murray-Rust, 1984;Murray-Rust & Motherwell, 1979;Ramasubbu, Parthasarathy & Murray-Rust, 1986). These O-..I interactions link the molecules to form zigzag chains (Fig.…”

Section: Table 2 Bond Lengths (A) Bond Angles (O) and Selected Torsmentioning

confidence: 97%

Structure of N-iodosuccinimide

Padmanabhan¹,

Paul²,

Curtin³

1990

Acta Crystallogr C Cryst Struct Commun

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“…Halogen bonding involves a favorable noncovalent interaction between a covalently-bonded halogen and a negative site, such as a lone pair. Such interactions were already known to experimentalists in the 19th century [3,4], and were studied extensively in the 20th [5][6][7][8][9][10], with crystallography playing a major role [10][11][12][13]. Nevertheless the basis for halogen bonding was not really understood.…”

mentioning

confidence: 99%

σ-Hole Interactions: Perspectives and Misconceptions

2017

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After a brief discussion of the σ-hole concept and the significance of molecular electrostatic potentials in noncovalent interactions, we draw attention to some common misconceptions that are encountered in that context: (1) Since the electrostatic potential reflects the contributions of both the nuclei and the electrons, it cannot be assumed that negative potentials correspond to "electron-rich" regions and positive potentials to "electron-poor" ones; (2) The electrostatic potential in a given region is determined not only by the electrons and nuclei in that region, but also by those in other portions of the molecule, especially neighboring ones; (3) A σ-hole is a region of lower electronic density on the extension of a covalent bond, not an electrostatic potential; (4) Noncovalent interactions are between positive and negative regions, which are not necessarily associated with specific atoms, so that "close contacts" between atoms do not always indicate the actual interactions.Keywords: σ-holes; noncovalent interactions; electrostatic potential; close contacts A Brief History of the σ-HoleThe σ-hole concept was introduced by Clark in the context of halogen bonding, at a conference in 2005 [1], although it did not appear in the chemical literature until 2007 [2]. Halogen bonding involves a favorable noncovalent interaction between a covalently-bonded halogen and a negative site, such as a lone pair. Such interactions were already known to experimentalists in the 19th century [3,4], and were studied extensively in the 20th [5][6][7][8][9][10], with crystallography playing a major role [10][11][12][13]. Nevertheless the basis for halogen bonding was not really understood. It was frequently rationalized as "charge transfer" from an electron "donor" (e.g., the lone pair) to an "acceptor" (the halogen), invoking the valence bond formalism of Mulliken [14] (which was later put in molecular orbital terms by Flurry [15,16]).However, the halogen is the most electronegative atom in each row of the periodic table, and a singly-bonded halogen atom is generally viewed as being negative in character. So why should it interact attractively with a donor of electronic charge? It was in fact pointed out long ago [7,17] that Mulliken's charge-transfer formalism was not intended to be an elucidation of the bonding in a ground-state noncovalent complex; it was purely a mathematical modeling of the transition of the ground-state complex to a low-lying excited state. The existence of halogen bonding was thus viewed by many as an enigma.The key to resolving the enigma was the molecular electrostatic potential. This is the potential V(r) that is created at any point r in the space of a molecule by its nuclei and electrons, given rigorously by Equation (1):Z A is the charge on nucleus A, located at R A , and ρ(r) is the molecule's electronic density. Regions in which V(r) is positive, indicating the dominance of the nuclear contribution, are attractive to

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Direct structural evidence for weak charge-transfer bonds in solids containing chemically saturated molecules

Cited by 239 publications

References 0 publications

The crystal structures of two sulphur-nitrogen compounds with (S–N)₃rings. II. Trithiazylchloride, (NSCl)₃, at –130°C

The crystal structures of two sulphur-nitrogen compounds with (S–N)₃rings. II. Trithiazylchloride, (NSCl)₃, at –130°C

Structure of N-iodosuccinimide

σ-Hole Interactions: Perspectives and Misconceptions

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Direct structural evidence for weak charge-transfer bonds in solids containing chemically saturated molecules

Cited by 239 publications

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The crystal structures of two sulphur-nitrogen compounds with (S–N)3rings. II. Trithiazylchloride, (NSCl)3, at –130°C

The crystal structures of two sulphur-nitrogen compounds with (S–N)3rings. II. Trithiazylchloride, (NSCl)3, at –130°C

Structure of N-iodosuccinimide

σ-Hole Interactions: Perspectives and Misconceptions

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The crystal structures of two sulphur-nitrogen compounds with (S–N)₃rings. II. Trithiazylchloride, (NSCl)₃, at –130°C

The crystal structures of two sulphur-nitrogen compounds with (S–N)₃rings. II. Trithiazylchloride, (NSCl)₃, at –130°C