Crystal structure of αZn2P2O7

Robertson, B. E.; Calvo, C.

doi:10.1016/0022-4596(70)90002-2

Cited by 87 publications

(49 citation statements)

References 7 publications

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“…(7) Calvo (1965a). (8) Robertson & Calvo (1970). (9) The six Or atoms all have relatively small and comparable temperature factors, and there is no indication that the differences in P-O distances are due to librational effects.…”

Section: Discussionmentioning

confidence: 99%

The crystal structure of calcium pyrophosphate dihydrate

Mandel¹

1975

Acta Crystallogr Sect B

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Crystals of calcium pyrophosphate dihydrate, Ca2P207.2H20, are triclinic, space group P], with a= 7.365 (4), b= 8.287 (4), c= 6.691 (4) A, ~= 102.96 (I) °, fl= 72.73 (1) °, and y=95.01 (1) °. There are two formula units per unit cell. Data were collected on an automated diffractometer at 25 °C using Mo Kc~ radiation; the structural parameters were refined to an R index of 0-037 for 4685 reflections. The six P-Or (terminal) bond lengths range from 1.499 (1) to 1.538 (1) A, with an average of 1.517 A; the two P-On (bridge) lengths are equal at 1.623 (1)/~. Average angles are On-P-Or, 107 ~, and Or-P-Or, 112'; the P-On-P angle is 123-1 (1) ~. A survey of known pyrophosphate structures shows the pyrophosphate anion to be extremely flexible and capable of adopting varied conformations with different cations. The two water molecules form one inter-water hydrogen bond and three hydrogen bonds to the pyrophosphate oxygens. Both calcium atoms are seven coordinated at Ca--. O distances less than 2-7 A.

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Section: Discussionmentioning

confidence: 99%

The crystal structure of calcium pyrophosphate dihydrate

Mandel¹

1975

Acta Crystallogr Sect B

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“…Hawthorne and Calvo (1978) suggested that longer (V-Obr) bond lengths of the divanadate groups in a series of structures are generally associated with smaller V-Obr-V angles. The same geometrical character is perceived also in other rare mixed-anion silicates with single and triple tetrahedral clusters: ardennite (Donnary and Allmann, 1968) and Ho4[SiO4] [Si3010 ] (Felsche, 1972), and in some disphosphates: o/-CuzP207 (Calvo, 1967), c~-Zn2P207 (Robertson and Calvo, 1970) and SiPzO 7 (Bissert and Liebau, 1970). Such a relationship between the T-Obr distances and the T-Obr-T angles may be common to some groups of the crystal structures with two tetrahedra sharing a vertex (pyroanion, T20~-): pyrosilicates, pyrovanadates, pyrophosphates and so on.…”

Section: Discussionmentioning

confidence: 67%

The crystal structure of manganoan kilchoanite, Ca_2.33Mn_0.67Si₂O₇: a site-preference rule for the substitution of Mn for Ca

Kimata¹

1989

Mineral. mag.

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The crystal structure of a Mn-bearin~ kilchoanite, Ca2.33Mn0.67Si2OT, orthorhombic, I2cm, a = 11.356(2), b = 5.007(1), c = 21.817(1)A, Z = 8, was refined using single-crystal X-ray data to an R value of 3.1% for 1725 unique reflections. It is isostructural with kilchoanite, Ca3Si20 > and shows a partial disorder of Mn and Ca over the four octahedral sites. On a basis of occupancy refinement, the M3 site ((M3-O} = 2.307 ~) contains 0.508Ca and 0.492Mn, and the M4 site ((M4-O) = 2.346 ~) contains 0.822Ca and 0.178Mn, whereas the M1 and M2 sites (

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“…The phase-determining procedures used in the solution of the structure are extensions of those previously developed and applied successfully to displacive superlattices by Calvo and co-workers (16)(17)(18)(19). In each case an average structure was determined first, using only the sublattice reflections, and subsequently the superlattice reflections were used to derive the small displacements characterising the true structure.…”

Section: Discussionmentioning

confidence: 99%

“…The co-ordination polyhedra so formed were reduced to points on a sphere, and analysed in terms of the interfacial angles by a program described previously (19).…”

Section: Discussionmentioning

confidence: 99%

“…With regard to possible eight, nine, and ten co-ordinate polyhedra available to the K+ ions, an analysis in terms of ligand-ligand repulsions, such as that carried out previously by one of us (19), would suggest that a centrosymmetric polyhedron, even when possible, will not be the most stable for that co-ordination number. For eight co-ordination the lowest energy centrosyrnmetric arrangement is the cube, while the polyhedra normally found are the square antiprism, bisdisphenoid and bicapped trigonal prism.…”

Section: Discussionmentioning

confidence: 99%

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Nitrosodisulphonates and hydroxylamine-N,N-disulphonates. V. A potassium salt of hydroxylamine-N,N-disulphonic acid with a displacive superlattice structure

Rütherford¹,

Robertson²,

Guttormson³

et al. 1988

Can. J. Chem.

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and hydroxylamine-N,N-disulphonates. V. A potassium salt of hydroxylamine-N,N-disulphonic acid with a displacive superlattice structure. Can. J. Chem. 66, 655 (1988).The structure of the potassium salt of hydroxylamine-N,N-disulphonate, with the formula KsHN2S40a14.H20, has been determined by X-ray diffraction. The crystals are triclinic, a = 14.01 1 (6), b = 16.1 18(9), c = 1 1.867(6) A. a = 103.28(6), p = 106.76(3), y = 86.38(3)", PI with Z = 6. The integrated intensities of 8694 independent reflections were measured on a four-circle diffractometer, 5236 of which were used in the refinement to give a final least-squares weighted residual of 0.107 and a conventional R factor of 0.081.The structure forms a six-fold derivative lattice, which arises by small displacements (ca. 0.2 A) of the atom ositions from an average structure which is triclinic with Z = 1. This results in three very short H bonds, average length 2.46 1 , which link the three independent anion-dimers, being symmetry-free in this structure. Other bond lengths and angles in the anions are very similar to those in the Rb salt. The K' ions show 8 , 9 , and I0 coordination, in a number of different polyhedral types. The three independent water molecules are each coordinated to three totally distinct K+ ions, and are linked to the anions by weak H bonds. The structural complexity 'may be explained in terms of a Lewis acid-base "mismatch" of the cations and anions present.

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Crystal structure of αZn2P2O7

Cited by 87 publications

References 7 publications

The crystal structure of calcium pyrophosphate dihydrate

The crystal structure of calcium pyrophosphate dihydrate

The crystal structure of manganoan kilchoanite, Ca_2.33Mn_0.67Si₂O₇: a site-preference rule for the substitution of Mn for Ca

Nitrosodisulphonates and hydroxylamine-N,N-disulphonates. V. A potassium salt of hydroxylamine-N,N-disulphonic acid with a displacive superlattice structure

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Crystal structure of αZn2P2O7

Cited by 87 publications

References 7 publications

The crystal structure of calcium pyrophosphate dihydrate

The crystal structure of calcium pyrophosphate dihydrate

The crystal structure of manganoan kilchoanite, Ca2.33Mn0.67Si2O7: a site-preference rule for the substitution of Mn for Ca

Nitrosodisulphonates and hydroxylamine-N,N-disulphonates. V. A potassium salt of hydroxylamine-N,N-disulphonic acid with a displacive superlattice structure

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The crystal structure of manganoan kilchoanite, Ca_2.33Mn_0.67Si₂O₇: a site-preference rule for the substitution of Mn for Ca