Structure of the oxalate ion

Dewar, Michael J. S.; Zheng, Yi

doi:10.1016/0166-1280(90)85053-p

Cited by 33 publications

(23 citation statements)

References 13 publications

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“…Ab initio calculations reported in several publications [5][6][7][8] have shown the free (C 2 O 4 ) 2À anion with torsion angle equal to 90 to be 0.274-0.294 eV/molecule lower in energy than a corresponding planar isomer. Staggered oxalate anions were recently observed in the structure of Cs 2 C 2 O 4 and in one of the two polymorphs of Rb 2 C 2 O 4 at ambient conditions [9], as well as in a few high-temperature polymorphs of Rb 2 C 2 O 4 , Cs 2 C 2 O 4 , K 2 C 2 O 4 [4].…”

Section: Introductionmentioning

confidence: 99%

Effect of hydrostatic pressure on the crystal structure of sodium oxalate: X-ray diffraction study and ab initio simulations

Boldyreva¹,

Ahsbahs²,

Чернышев³

et al. 2006

Zeitschrift Für Kristallographie - Crystalline Materials

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Effect of hydrostatic pressures up to 8 GPa on the crystals of Na 2 C 2 O 4 (sp. gr. P2 1 /c) was studied in situ in the diamond anvil cells a) in neon, b) in methanol-ethanol mixture by high-resolution X-ray powder diffraction (synchrotron radiation, l ¼ 0.7 A, MAR345-detector). Below 3.3-3.8 GPa, anisotropic structural distortion was observed, which was similar to, but not identical with that on cooling. At 3.8 GPa, a reversible isosymmetric first-order phase transition without hysteresis occurred. The orientation of the oxalate anions changed at the transition point by a jump, and so did the coordination of the sodium cations by oxygen atoms. Ab initio simulations based on the generalized gradient approximation of density functional theory have reproduced the main features of the structural changes in the crystals of sodium oxalate with increasing pressure. The theoretical pressure for the isosymmetric phase transition is 3.65 GPa, close to the experimental value; in agreement with experiment the transition was predicted to be reversible. Ab initio calculations gave a pronounced hysteresis for this transition, and have also predicted a further isosymmetric phase transition at 10.9 GPa, also with a hysteresis. The role of temperature in the pressure-induced phase transitions in sodium oxalate is discussed.

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Section: Introductionmentioning

confidence: 99%

Effect of hydrostatic pressure on the crystal structure of sodium oxalate: X-ray diffraction study and ab initio simulations

Boldyreva¹,

Ahsbahs²,

Чернышев³

et al. 2006

Zeitschrift Für Kristallographie - Crystalline Materials

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“…Interesting to notice is the fact that the HC O\ group, like the C O\ group, is almost planar. From a theoretical study (12), it was expected that in salts with rather bulky cations, the orthogonal conformer might be the preferred form, although the calculated energy di!erence between the two coformers was quite low (&1.6 kcal mol\).…”

Section: Discussionmentioning

confidence: 98%

Structure Determination and Refinement of Acid Strontium Oxalate from X-Ray and Neutron Powder Diffraction

Vanhoyland

Bourée

Bael

et al. 2001

Journal of Solid State Chemistry

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“…1 4 compounds of molybdenum and tungsten. 2,3,[14][15][16][17][18] It is, however, known that the oxalate anion in water has a twisted D 2d structure and calculations by Dewar and Zheng predicted that the gas-phase structure of 19 There is no formal C-C π bond and the C-C distance of 1.57(1) Å seen in K 2 C 2 O 4 ·H 2 O is very long. 20,21 However, complexation to metal ions as in oxalate complexes of Cr(III) or Al(III), which have D 3 symmetry, favors planar oxalate by virtue of the formation of five-membered chelate rings.…”

Section: Dimers Of Dimersmentioning

confidence: 99%

Electronic coupling between molybdenum and tungsten quadruple bonds in molecular squares and extended chains linked by oxalate, acetylenedicarboxylate, and perfluoroterephthalate bridges

Bursten

Chisholm

Hadad

et al. 2001

Israel Journal of Chemistry

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The electronic structures of dicarboxylate-bridged complexes containing dimolybdenum and ditungsten quadruple bonds have been investigated using density function theory (gradient corrected and time-dependent), which reveals the consequences of strong mixing of M 2 δ and oxalate π orbitals within extended chains and cyclic structures. Where the bridge is oxalate, acetylene dicarboxylate, and perfluoroterephthalate (PFT), the M 2 centers are in all cases strongly coupled through M 2 δ to bridge π-conjugation. In the case of the chain compounds, this is strongly mediated by torsion angles along the chain. For the squares, only when the bridge is PFT is there a dependence on the orientation of the phenyl ring.

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Structure of the oxalate ion

Cited by 33 publications

References 13 publications

Effect of hydrostatic pressure on the crystal structure of sodium oxalate: X-ray diffraction study and ab initio simulations

Effect of hydrostatic pressure on the crystal structure of sodium oxalate: X-ray diffraction study and ab initio simulations

Structure Determination and Refinement of Acid Strontium Oxalate from X-Ray and Neutron Powder Diffraction

Electronic coupling between molybdenum and tungsten quadruple bonds in molecular squares and extended chains linked by oxalate, acetylenedicarboxylate, and perfluoroterephthalate bridges

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