Crystal structure at 100 K of bis[1,2-bis(diphenylphosphanyl)ethane]nickel(II) bis(trifluoromethanesulfonate): a possible negative thermal expansion molecular material

• Published in: Acta crystallographica. Section E, Crystallographic communications Vol. 74; no. 11; pp. 1678 - 1681
• Main Authors: Cano-Benítez, Cristian A., Metta-Magaña, Alejandro J., Duarte-Ruiz, Álvaro
• Format: Journal Article
• Language: English
• Published: International Union of Crystallography 01-11-2018
• Subjects: 100 K; crystal structure; dppe; Negative thermal expansion; NTE; square-planar geometry
• ISSN: 2056-9890; 2056-9890
• DOI: 10.1107/S2056989018014846

In the title salt, [Ni(C
26
H
24
P
2
)
2
](CF
3
SO
3
)
2
or [Ni(dppe)
2
]
2+
·(OTf
−
)
2
[dppe = 1,2-bis(diphenylphosphanyl)ethane and OTf
−
= trifluoromethanesulfonate], the Ni atom (site symmetry \overline{1}) has a square-planar geometry with the bidentate ligands chelating the metal. As a result of the steric hindrance of the phenyl rings, the counter-ions are blocked from the metal coordination sphere. The dynamic disorder of the anion existing at 296 K is reduced at 100 K and based on these two temperatures, negative thermal expansion behaviour is observed.