Sökning: onr:"swepub:oai:research.chalmers.se:265b74b3-5524-44f8-9fa5-94166e4a8078" >
Conformational chiral polymorphism in cis-bis-triphenylphosphine complexes of transition metals
-
- Tshabang, Never (författare)
- University of Botswana
-
- Makgatle, Gaone P. (författare)
- University of Botswana
-
- Bourne, S. A. (författare)
- University of Cape Town
-
visa fler...
-
- Kann, Nina, 1964 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
-
- Evans, Jack D. (författare)
- Institut de Recherche de Chimie Paris,Technische Universität Dresden
-
- Coudert, François Xavier (författare)
- Institut de Recherche de Chimie Paris
-
- Öhrström, Lars, 1963 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
-
visa färre...
-
(creator_code:org_t)
- 2018
- Engelska.
-
Ingår i: CrystEngComm. - 1466-8033. ; 20:35, s. 5137-5142
- Relaterad länk:
-
https://research.cha... (primary) (free)
-
visa fler...
-
https://research.cha...
-
https://doi.org/10.1...
-
https://research.cha...
-
visa färre...
Abstract
Ämnesord
Stäng
- The structure of cis-[Mo(CO)4(PPh3)2] 1 was determined by F. A. Cotton, D. J. Darensbourg, S. Klein and B. W. S. Kolthammer, Inorg. Chem., 1982, 21, 1651-1655, with the space group P1. A second polymorph 2 is reported here, with the space group P21/c. The compounds differ in the interactions between the conformational chiral triphenylphosphine groups. In 1, there is π-π stacking between adjacent phenyl groups, whereas in 2, there are σ-π interactions instead. A search of the Cambridge Structural Database reveals that this is a relatively frequent occurrence in cis-bis-triphenylphosphine complexes and the phenomenon can be analysed by means of the C(ipso)-P-M-P torsion angles. The majority of compounds fall in the π-π stacking data area with torsion angles of 10-15° and 55-60°; however, for octahedrally coordinated metals, the optimum is a σ-π interaction at 40°/40°. This corresponds well to the values in 2: 46°/40°, but for 1, we instead find the torsion angles to be 11°/18°. There is indeed a small occurrence of these values as well in the data, and it appears that for 1, this conformation is stabilised by weak COH-C hydrogen bonds. Density functional theory (DFT) calculations indicate that 1 is the more stable polymorph by 72 kJ mol−1but that the strain of the complexes (the difference between a relaxed molecule in the respective conformation and the structure in the crystal) is larger for 1 than for 2, further indicating that a special intermolecular interaction is responsible for the stability of this polymorph. In both polymorphs, the triphenylphosphines have the same conformational chirality, consistent with single-molecule calculations that predict racemic conformations to be substantially higher in energy for both σ-π interactions (+17 kJ mol−1) and π-π stacking (+30 kJ mol−1).
Ämnesord
- NATURVETENSKAP -- Kemi -- Oorganisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)
- NATURVETENSKAP -- Kemi -- Teoretisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)