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Exploring secondary bonding in p-block chemistry – an experimental study of [GeX2{o-C6H4(PMe2)2}] using variable pressure single crystal X-ray diffraction

Exploring secondary bonding in p-block chemistry – an experimental study of [GeX2{o-C6H4(PMe2)2}] using variable pressure single crystal X-ray diffraction
Exploring secondary bonding in p-block chemistry – an experimental study of [GeX2{o-C6H4(PMe2)2}] using variable pressure single crystal X-ray diffraction
Secondary bonding interactions play a major role in governing the overall structures adopted. The low energy contributions from these weak interactions make structure prediction very difficult, hence there is a need for experimental techniques that contribute to understanding the interplay between different types of secondary bonding. Variable pressure single crystal X-ray diffraction studies on the homologous series, [GeX2{o-C6H4(PMe2)2}], X = Cl 1, Br 2, I 3, show that probing the different interfaces between layers of structural building blocks, rather than conventional molecular units, provides very valuable insights. 1 and 3 undergo a smooth compression as the pressure is increased, whereas a phase transition occurs for 2 at a pressure between 29 and 41 kbar. This is associated with an abrupt change in the beta angle (from 111.33(2)degrees to 92.24(8)degrees). The structural consequences are most evident in the aromatic. aromatic layer interface. Below the phase transition there is an edge-to-face C-H ···pi arrangement (like 1), with the angle between the planes of adjacent rings of similar to 75 degrees, whereas above the transition this interface has transformed to an offset-parallel face-to-face pi-pi stacking interaction (like 3). The GeX2 ··· X2Ge interface undergoes a concomitant, but smoother compression with increasing pressure. 2 also has the highest void volume at ambient pressure (11.9%), and as expected the phase transition results in a structure with much more efficient packing. This, the first such study involving p-block coordination complexes, reveals the subtlety and complexity of the interplay between the different forms of weak, secondary (supramolecular) interactions present. The results indicate that this type of experimental study can provide valuable additional information to help guide crystal structure prediction by computational methods, an important and very challenging target.
1466-8033
8169-8176
Allan, David R.
311ec351-bbfd-4e05-bfd4-c571b7cb5f21
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
George, Kathryn
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Jura, Marek
d145b3fa-eec4-47d8-b47c-61a2b616bc8f
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Wilson, Claire
6be18134-9a9f-4d19-8197-0593a648773f
Zhang, Wenjian
1f80ac5e-d4c2-4720-b19e-be700cd411e7
Allan, David R.
311ec351-bbfd-4e05-bfd4-c571b7cb5f21
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
George, Kathryn
1e9bf4f9-226e-446e-9ef3-dd61c7f7aa11
Jura, Marek
d145b3fa-eec4-47d8-b47c-61a2b616bc8f
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Wilson, Claire
6be18134-9a9f-4d19-8197-0593a648773f
Zhang, Wenjian
1f80ac5e-d4c2-4720-b19e-be700cd411e7

Allan, David R., Coles, Simon J., George, Kathryn, Jura, Marek, Levason, William, Reid, Gillian, Wilson, Claire and Zhang, Wenjian (2014) Exploring secondary bonding in p-block chemistry – an experimental study of [GeX2{o-C6H4(PMe2)2}] using variable pressure single crystal X-ray diffraction. CrystEngComm, 16 (35), 8169-8176. (doi:10.1039/C4CE00329B).

Record type: Article

Abstract

Secondary bonding interactions play a major role in governing the overall structures adopted. The low energy contributions from these weak interactions make structure prediction very difficult, hence there is a need for experimental techniques that contribute to understanding the interplay between different types of secondary bonding. Variable pressure single crystal X-ray diffraction studies on the homologous series, [GeX2{o-C6H4(PMe2)2}], X = Cl 1, Br 2, I 3, show that probing the different interfaces between layers of structural building blocks, rather than conventional molecular units, provides very valuable insights. 1 and 3 undergo a smooth compression as the pressure is increased, whereas a phase transition occurs for 2 at a pressure between 29 and 41 kbar. This is associated with an abrupt change in the beta angle (from 111.33(2)degrees to 92.24(8)degrees). The structural consequences are most evident in the aromatic. aromatic layer interface. Below the phase transition there is an edge-to-face C-H ···pi arrangement (like 1), with the angle between the planes of adjacent rings of similar to 75 degrees, whereas above the transition this interface has transformed to an offset-parallel face-to-face pi-pi stacking interaction (like 3). The GeX2 ··· X2Ge interface undergoes a concomitant, but smoother compression with increasing pressure. 2 also has the highest void volume at ambient pressure (11.9%), and as expected the phase transition results in a structure with much more efficient packing. This, the first such study involving p-block coordination complexes, reveals the subtlety and complexity of the interplay between the different forms of weak, secondary (supramolecular) interactions present. The results indicate that this type of experimental study can provide valuable additional information to help guide crystal structure prediction by computational methods, an important and very challenging target.

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Published date: 4 April 2014
Organisations: Organic Chemistry: Synthesis, Catalysis and Flow, Chemistry, Faculty of Natural and Environmental Sciences

Identifiers

Local EPrints ID: 369312
URI: http://eprints.soton.ac.uk/id/eprint/369312
ISSN: 1466-8033
PURE UUID: 1ffa5d1d-2dd0-469f-8160-3f0910a83411
ORCID for Simon J. Coles: ORCID iD orcid.org/0000-0001-8414-9272
ORCID for William Levason: ORCID iD orcid.org/0000-0003-3540-0971
ORCID for Gillian Reid: ORCID iD orcid.org/0000-0001-5349-3468

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Date deposited: 30 Sep 2014 13:41
Last modified: 04 Aug 2021 01:36

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Contributors

Author: David R. Allan
Author: Simon J. Coles ORCID iD
Author: Kathryn George
Author: Marek Jura
Author: William Levason ORCID iD
Author: Gillian Reid ORCID iD
Author: Claire Wilson
Author: Wenjian Zhang

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