Negative and zero linear compressibility in copper dicyanamide and tricyanomethanide
Muzi Chen1,2, Hanna L B Boström3,4, Dominik Daisenberger5
1Department of Materials, Imperial College London, Royal School of Mines Exhibition Road SW7 2AZ London UK a.cairns@imperial.ac.uk muzichen@kofo.mpg.de Tel: +44(0)20 7594 9528.
Chemical Science
|January 5, 2026
Summary
Transition metal dicyanamides (dca) and tricyanomethanides (tcm) exhibit unique compression behaviors. Cu(dca)2 shows negative linear compressibility, expanding under pressure, while Cu(tcm)2 displays zero linear compressibility.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- Rutile-structured materials can exhibit negative linear compressibility (NLC) after ferroelastic phase transitions, expanding along one dimension under compression.
- Investigating NLC in transition metal dicyanamides (dca) and tricyanomethanides (tcm) provides insights into structure-property relationships.
Purpose of the Study:
- To explore the pressure-induced structural behavior of Cu(dca)2 and Cu(tcm)2.
- To understand the factors controlling negative and zero linear compressibility in these materials.
- To investigate the interplay between structural features, Jahn-Teller distortion, and compression behavior.
Main Methods:
- High-pressure diffraction studies were conducted on Cu(tcm)2 and Cu(dca)2.
- Anisotropic deformation upon compression was analyzed.
- The influence of network flexibility and interpenetration on compressibility was examined.
Main Results:
- Cu(dca)2 exhibited negative linear compressibility (NLC) of -6.5(10) TPa⁻¹ along the c-axis.
- Cu(tcm)2 displayed zero linear compressibility (ZLC) along the a-axis.
- Differences in compressibility were linked to the single rutile-like network of Cu(dca)2 versus the doubly interpenetrating structure of Cu(tcm)2.
Conclusions:
- The flexibility of dca⁻ linkers in Cu(dca)2 facilitates NLC, contrasting with the rigid tcm⁻ linkers in Cu(tcm)2.
- Structural characteristics, including network topology and linker rigidity, significantly influence compressibility.
- Jahn-Teller distortions play a role in modulating the compression behavior of these materials.
More Related Videos
13:34Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium
Published on: July 8, 2015
9.5K
12:05Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia
Published on: October 10, 2013
15.9K
Related Concept Videos
03:02Colors and Magnetism
13.9K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
13.9K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
47.9K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
47.9K
01:18Aromatic Hydrocarbon Cations: Structural Overview
3.6K
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group...
Removing one hydrogen from the intervening CH2 group...
3.6K
01:18Aromatic Hydrocarbon Anions: Structural Overview
3.5K
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous...
Due to the absence of continuous...
3.5K
02:42Valence Bond Theory
11.1K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
11.1K
02:11Conformations of Cyclohexane
15.1K
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
15.1K