Bonding in the two-dimensional copper-gallium layer of a calcium copper gallium, Ca2Cu2Ga, crystal

Kollmar, Christian; Hoffmann, Roald

doi:10.1021/ic00338a016

Cited by 8 publications

(5 citation statements)

References 11 publications

(17 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This leads to the formation of layers {CoB 2 } separated by W atoms. A different situation is observed in K 2 Au 3 and Ca 2 GaCu 2 . , The Au2 and Cu atoms form a continuous chain along [010] with alternating short and long distances, d 1 (Au2–Au2) = 2.68 Å, and the longest distance is d 2 (Au2–Au2) = 2.76 Å, respectively. In Ca 2 GaCu 2 , these two distances are 2.70 and 2.78 Å, respectively.…”

Section: Resultsmentioning

confidence: 99%

Mg₃Pt₂: Anionic Chains in a Eu₃Ga₂-Type Structure

et al. 2021

View full text Add to dashboard Cite

The binary phase Mg 3 Pt 2 was prepared by direct reaction between the elements or by spark-plasma synthesis starting with MgH 2 and PtCl 2 . The compound crystallizes in the monoclinic space group C 2/ c with a = 7.2096(3) Å, b = 7.1912(4) Å, c = 6.8977(3) Å, and β = 106.072(3)° and is isotypic to Eu 3 Ga 2 . Analysis of the electron density within the quantum theory of atoms in molecules shows a significant charge transfer from Mg to Pt in agreement with the electronegativity difference. Further study of the chemical bonding with the electron localizability approach reveals the formation of Pt chains stabilized by a complex system of multicenter interactions involving Mg and Pt species. The metallic character of Mg 3 Pt 2 is confirmed by electronic structure calculations and physical measurements.

show abstract

Section: Resultsmentioning

confidence: 99%

Mg₃Pt₂: Anionic Chains in a Eu₃Ga₂-Type Structure

et al. 2021

View full text Add to dashboard Cite

show abstract

“…As an alternate view, we have the classic example of the extended‐Hückel MO study of the parent Ca 2 Cu 2 Ga by Kolimar and Hoffmann ,36 in which the pair‐wise distortions of the infinite copper chains are relatively small, only 0.08 Å. We have carried out three such calculations for the platinum analogue, as shown in Figure 3: (a) the Pt–Pt chain alone (two atoms per cell), (b) the two‐dimensional Pt 2 Cd layer, and (c) the three‐dimension structure with calcium.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Structure, and Bonding Analysis of the Polar Intermetallic Phase Ca₂Pt₂Cd

Samal

Corbett

2012

Zeitschrift anorg allge chemie

View full text Add to dashboard Cite

Cd. -The title compound is prepared from the elements (Ta containers, 900 C, 12 h; annealing at 600 C for 4 d). Ca 2 Pt 2 Cd crystallizes in the orthorhombic space group Immm with Z = 2 (single crystal XRD). The structure contains infinite, planar networks of [Pt 2 Cd] 4-groups, which can be described as tessellation of six-and four-membered rings of the anions. The Ca 2+ cations are located between the anionic layers. The Pt chains show a substantial long-short distortion of 0.52 Å. LMTO-ASA calculations reveal that the new compound is metallic in nature, and the overall bond populations are dominated by Ca-Pt bonds. -(SAMAL, S. L.; CORBETT*, J. D.; Z. Anorg. Allg. Chem. 638 (2012Chem. 638 ( ) 12-13, 1963Chem. 638 ( -1969 7-Double-Chain. -The title compound is prepared by reaction of Ca with Si(NH) 2 and Li 3 N using Li as a flux (sealed Ta ampule, 900 C, 12 h). The compound crystallizes in the monoclinic space group C2/c with Z = 8 (single crystal XRD). The structure contains [Si 2 ] double chains of corner-and edge-sharing SiN 4 tetrahedra. The Li atoms are situated in strands along the crystallographic b axis. The compound is further characterized by 29 Si and 7 Li MAS NMR spectroscopy. -(LUPART, S.; SCHNICK*, W.; Z. Anorg. Allg. Chem. 638 (2012) 12-13, 2015-2019, http -Yellow single crystals of the title compound are prepared by solid state reaction of a stoichiometric mixture of anhydrous Na 2 Se, Sb, and Se in a 3:2:3 ratio (evacuated silica ampule, 723 K, 10 weeks). Na 3 SbSe 3 crystallizes in the cubic space group P2 1 3 with Z = 4 (single crystal XRD). The structure contains trigonal SbSe 3 pyramids, which act as mono-, bi-, and tridentate ligands to sodium. There are three different Na sites, which are all coordinated by six Se atoms, providing a strongly distorted octahedral environment. NaSe 6 octahedra of identical type share common vertices. Na 3 SbSe 3 exhibits temperature dependent Na + conductivity above 380 K. The compound is further characterized by Raman spectroscopy. -(POMPE, C.; PFITZNER*, A.; Z. Anorg. Allg. Chem. 638 (2012) (1200 C, 8 h) and characterized by powder XRD and photoluminescence spectroscopy. Excitation and reflectance spectra of this phosphor show broad band excitation and absorption in the 240-470 nm near UV region, indicating its potential application in near UV diode based white-light LEDs. With the optimal Eu 2+ doping concentration of 0.01 mol, the phosphor exhibits strong yellow emission centered at 512 and 606 nm. It may have potential applications as a yellow-emitting near UV convertible phosphor in fabricating warm white-light LEDs with excellent color rendering index. 3 , Ta 2 O 5 , and Na 2 C 2 O 4 using urea as complexing agent and fuel (600 C, 4 h). The band gaps of the Bi 2 O 3 /Bi-NaTaO 3 samples can be tuned to effectively absorb visible light and induce visible light photocatalytic activity by varying the bismuth concentration. Photoluminescence studies confirm that the optimum amount of Bi effectively suppresses the recombination rate of...

show abstract

“…In the last two groups, the metal pairs are aligned linearly, in a manner that is reminiscent of a Peierls distortion, but the extent of the pairing distortion is always larger in the orthorhombic W 2 CoB 2 -type than in the monoclinic Gd 2 AlGe 2 -type structure. Nevertheless, analysis of the bonding in Ca 2 Cu 2 Ga has concluded that Peierls -type distortion mechanism is very unlikely in the system . Thus, the exact mechanism of the pairing distortion was still unclear.…”

Section: Introductionmentioning

confidence: 99%

Linear Metal Chains in Ca₂M₂X (M = Pd, Pt; X = Al, Ge): Origin of the Pairwise Distortion and Its Role in the Structure Stability

et al. 2014

View full text Add to dashboard Cite

A series of four new analogue phases Ca 2 M 2 X (M = Pd, Pt and X = Al, Ge) were prepared by direct combination of the respective elements in stoichiometric mixtures at high temperature in order to analyze the impact of valence electron count (vec) and electronegativity differences (Δχ) on the structure selection and stability. Their crystal structures, as determined from single-crystal X-ray diffraction data, correspond to two different but closely related structure types. The first compound, Ca 2 Pd 2 Ge (I), is an unprecedented ternary ordered variant of the Zr 2 Al 3 -type (orthorhombic, Fdd2). The three other phases, Ca 2 Pt 2 Ge (II), Ca 2 Pd 2 Al (III) and Ca 2 Pt 2 Al (IV), adopt the Gd 2 Ge 2 Al-type structure (monoclinic, C2/c). All title structures feature linear chains of the noble metals (Pd or Pt). The Pd linear chains in I are undistorted with equidistant Pd···Pd atoms, whereas the metal chains in II-IV are pairwise distorted, resulting in short connected {Pd 2 } or {Pt 2 } dumbbells that are separated by longer M···M contacts. The occurrence and magnitude of the pairing distortion in these chains are controlled by the vec and the Δχ between the constituent elements, a result which is supported by analysis of the calculated Bader effective charges. The metal chains act as charge modulation units, critical for the stability and the electronic flexibility of the structures by an adequate adjustment of the metal-metal bond order to both the vec and the degree of charge transfer. Thus, Ca 2 Pd 2 Ge (28 ve/f.u) is a Zintl-like, charge optimized phase with formally zerovalent Pd atoms forming the undistorted metal chains; semimetallic properties are predicted by TB-LMTO calculations. In contrast, the isoelectronic Ca 2 Pt 2 Ge is predicted to be a good metal with the Fermi level located at a local maximum of the DOS, a fingerprint of potential electronic instability. This is due to greater charge transfer to the more electronegative Pt atoms forming the metal chains and probably to packing frustration in the well packed structure that may prevent a larger distortion of the Pt chains. However, the instability is suppressed in the aliovalent but isostructural phases Ca 2 M 2 Al (27 ve/f.u) with an enhancement of the pairing distortion within the metal chains but lower M-M bond order. Further reduction of the vec as in Ca 2 M 2 Cd (26 ve/f.u) may induce a transition toward the more geometrically flexible W 2 CoB 2 -type with a low dimensional structure, to create more room for a larger distortion of the metal chain as dictated by the shortage of valence electrons. ABSTRACT: A series of four new analogue phases Ca 2 M 2 X (M = Pd, Pt and X = Al, Ge) were prepared by direct combination of the respective elements in stoichiometric mixtures at high temperature in order to analyze the impact of valence electron count (vec) and electronegativity differences (Δχ) on the structure selection and stability. Their crystal structures, as determined from single-crystal X-ray diffraction data, correspond to two ...

show abstract

Bonding in the two-dimensional copper-gallium layer of a calcium copper gallium, Ca2Cu2Ga, crystal

Cited by 8 publications

References 11 publications

Mg₃Pt₂: Anionic Chains in a Eu₃Ga₂-Type Structure

Mg₃Pt₂: Anionic Chains in a Eu₃Ga₂-Type Structure

Synthesis, Structure, and Bonding Analysis of the Polar Intermetallic Phase Ca₂Pt₂Cd

Linear Metal Chains in Ca₂M₂X (M = Pd, Pt; X = Al, Ge): Origin of the Pairwise Distortion and Its Role in the Structure Stability

Contact Info

Product

Resources

About

Bonding in the two-dimensional copper-gallium layer of a calcium copper gallium, Ca2Cu2Ga, crystal

Cited by 8 publications

References 11 publications

Mg3Pt2: Anionic Chains in a Eu3Ga2-Type Structure

Mg3Pt2: Anionic Chains in a Eu3Ga2-Type Structure

Synthesis, Structure, and Bonding Analysis of the Polar Intermetallic Phase Ca2Pt2Cd

Linear Metal Chains in Ca2M2X (M = Pd, Pt; X = Al, Ge): Origin of the Pairwise Distortion and Its Role in the Structure Stability

Contact Info

Product

Resources

About

Mg₃Pt₂: Anionic Chains in a Eu₃Ga₂-Type Structure

Mg₃Pt₂: Anionic Chains in a Eu₃Ga₂-Type Structure

Synthesis, Structure, and Bonding Analysis of the Polar Intermetallic Phase Ca₂Pt₂Cd

Linear Metal Chains in Ca₂M₂X (M = Pd, Pt; X = Al, Ge): Origin of the Pairwise Distortion and Its Role in the Structure Stability