Redetermination of the Crystal Structure of Calcium Cyanamide

Yamamoto, Yūzō; Kinoshita, Kyoji; Tamaru, Kenzi; Yamanaka, Teruko

doi:10.1246/bcsj.31.501

Cited by 12 publications

(6 citation statements)

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“…The interatomic distances of C-N, calculated from spectroscopic data (752), are close to those obtained by X-ray techniques (845) (1.255 and 1.25 A, respectively), thus favoring a symmetrical structure. The infrared spectra of cyanamide dihydrochloride and its deuterated form show that the compounds are ionic; in salt formation the protons of the acid are therefore transferred totally (or almost so) to the nitrogen.…”

Section: Physical Propertiessupporting

confidence: 71%

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Advances in the Chemistry of Carbodiimides

Kurzer¹,

1967

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Section: Physical Propertiessupporting

confidence: 71%

“…has been considered by many workers (38,147,287,314,333,648,752,845). In attempts to study this question more closely, the molecular structure of cyanamide has been examined by a number of physical methods, under various conditions.…”

Section: Physical Propertiesmentioning

confidence: 99%

Advances in the Chemistry of Carbodiimides

Kurzer¹,

1967

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“…18,19 Compounds with [NCN] 2ions have been known much longer than those with [NBN] 3ions. Examples of wellknown A 2 (CN 2 ) and AE(CN 2 ) compounds include alkali [20][21][22][23] and alkali earth [24][25][26][27][28][29][30] elements, with Ca(CN 2 ) 27 being presumably the most striking example, because of its applications, for example, in organic synthesis and in soil treatments. Compounds with analogous compositions to those of the alkali or alkali earth elements are known for group 11 and 12 elements, [31][32][33][34] and recently, Mn(CN 2 ) was reported to adopt the Ca(CN 2 ) structure.…”

Section: Introductionmentioning

confidence: 99%

Syntheses and Structural Properties of Rare Earth Carbodiimides

2006

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Crystalline samples of rare earth carbodiimides were synthesized by solid-state metathesis reactions of rare earth trichlorides with lithium cyanamide in sealed silica ampules. Two distinct structures were determined by single-crystal X-ray diffraction. The structure determined for Sm2(CN2)3 [C2/m, Z = 2, a = 14.534(2) A, b = 3.8880(8) A, c = 5.2691(9) A, beta = 95.96(2) degrees , R1 = 0.0267, and wR2 = 0.0667] was assigned for RE2(CN2)3 compounds with RE = Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, and the structure determined for Lu2(CN2)3 [R32, Z = 3, a = 6.2732(8) A, c = 14.681(2) A, R1 = 0.0208, and wR2 = 0.0526] was assigned for the smallest rare earth ions with RE = Tm, Yb, and Lu by powder X-ray diffraction. Both types of crystal structures are characterized by layers of [NCN](2-) ions whose arrangements can be derived from the motif of a closest packed layer of sticks. These layers alternate with layers of rare earth ions in a one-by-one sequence. Different tilting arrangements of the N-C-N-axes relative to the stacking directions (c) and different arrangements of RE3+ ions within metal atom layers account for the two distinct structures in which Sm3+ and Lu3+ ions adopt the coordination numbers 7 and 6, respectively.

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“…Phonon computations were conducted using the program PHONOPY based on the Hellmann–Feynman forces calculated using VASP. The supercells for the force calculations were set up by multiplying the unit cells in each direction such that the lattice parameters of the supercells were well above 10 Å. Thermodynamic potentials were obtained in the framework of the quasi-harmonic approximation. , The calculations were conducted for the crystal structures of all of the alkaline-earth metal carbodiimides, alkaline-earth metals, graphite, and crystalline nitrogen. ,,,− …”

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Melting Behavior of Alkaline-Earth Metal Carbodiimides and Their Thermochemistry from First-Principles

et al. 2019

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We present a combined experimental and theoretical investigation targeted at the thermochemical properties of a series of alkaline-earth metal carbodiimides. Their Gibbs energies and decomposition temperatures were calculated on the basis of phonons derived from density functional theory. The theoretical decomposition temperatures arrive at 1270, 1224, and 1185 K for CaNCN, α-SrNCN, and tetragonal BaNCN, respectively. Only the melt of tetragonal BaNCN is maintained at ∼1173 K, which is slightly below its calculated decomposition temperature. Experimentally, the melt of BaNCN did not decompose below 1273 K. On the contrary, both CaNCN and α-SrNCN partially decompose by forming a mixture of their carbides, metals, and nitrogen. The calculated Gibbs energies also show that the tetragonal phase of BaNCN is more stable than the rhombohedral one. We conclude that the melt of BaNCN is useful in the crystal growth of oxynitride perovskites such as BaTaO 2 N.

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Redetermination of the Crystal Structure of Calcium Cyanamide

Abstract: The crystal structure of calcium cyanamide has been studied by Dehlinger and Hanawalt, and later by Bredig1). Bredig reached the conclusion from his Debye-Scherrer X-ray analysis that the crystal structure of calcium cyanamide is based upon a rhombohedral lattice with

Cited by 12 publications

References 1 publication

Advances in the Chemistry of Carbodiimides

Advances in the Chemistry of Carbodiimides

Syntheses and Structural Properties of Rare Earth Carbodiimides

Melting Behavior of Alkaline-Earth Metal Carbodiimides and Their Thermochemistry from First-Principles

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