Syntheses, Vibrational Spectroscopy, and Crystal Structure Determination from X-Ray Powder Diffraction Data of Alkaline Earth Dicyanamides M[N(CN)2]2 with M=Mg, Ca, Sr, and Ba

Jürgens, Barbara; Irran, Elisabeth; Schnick, Wolfgang

doi:10.1006/jssc.2000.9036

Cited by 61 publications

(61 citation statements)

References 20 publications

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“…The spectra show broad signals belonging to CϵN and CϭN bonds which can indicate a further polymerization of the dicyanamide ions to extended C-N networks of unknown structure. Similar spectra were observed for the thermolysis products of the divalent dicyanamides M[N(CN) 2 ] 2 (M ϭ Mg, Ca, Sr, Ba, Pb, Co, Ni) [10,11,22]. Temperature-dependent Xray measurements were performed on a STOE Stadi P powder diffractometer (Mo-Kα 1 radiation) with a computer controlled STOE furnace.…”

Section: Thermal Behaviormentioning

confidence: 78%

“…Besides solvent containing complexes, the chemistry of solvent-free ternary dicyanamides was studied as well: The salts M II [N(CN) 2 ] 2 (M ϭ Mg, Cr, Mn, Co, Ni, Cu) were found to crystallize in a rutile-analogous structure type [7Ϫ10]. The structure of M II [N(CN) 2 ] 2 (M ϭ Ba, Pb) [10Ϫ12] derives from the cotunnite structure type (PbCl 2 ), whereas M II [N(CN) 2 ] 2 (M ϭ Ca, Sr) form a new structure type [10].…”

Section: Introductionmentioning

confidence: 99%

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Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)₂]₂

Jürgens¹,

Irran²,

Höppe³

et al. 2004

Zeitschrift anorg allge chemie

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Cadmium dicyanamide Cd[N(CN) 2 ] 2 was synthesized through aqueous ion exchange at room temperature. A reversible phase transition was detected by in situ X-ray powder diffractometry above 55°C. The crystal structures of both phases were determined by X-ray powder diffraction (β-Cd[N(CN) 2 ] 2 : T ϭ 22°C, a ϭ 621.60(3), b ϭ 748.76(4), c ϭ 770.21(5) pm, β ϭ 91.784(3)°, P2 1 /n (no. 14), Z ϭ 2, wR p ϭ 0.063, R p ϭ 0.050, R F ϭ 0.059; α-Cd[N(CN) 2 ] 2 : T ϭ 150°C, a ϭ 624.62(5), b ϭ 752.92(6), c ϭ 768.30(7) pm, Pnnm (no. 58), Z ϭ 2, wR p ϭ 0.083, R p ϭ 0.064,

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Section: Thermal Behaviormentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)₂]₂

Jürgens¹,

Irran²,

Höppe³

et al. 2004

Zeitschrift anorg allge chemie

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“…Thermolysis of the dicyanamides initiates oligomerization and polymerization processes, leading to extended C/N species. For example, thermolysis of M II [N(CN) 2 ] 2 (M = Mg, Ca, Sr, Ba, Pb) [38,47] or Ln III [N(CN) 2 ] 3 (Ln = La, Ce, Pr, Sm, Nd, Eu, Gd, Tb) [44,46] leads to amorphous products containing undefined polymeric C/N networks, whereas thermolysis of alkali metal dicyanamides (Scheme 1). [35,37,48] The tricyanomelaminates are built up from a planar s-tri-A C H T U N G T R E N N U N G azine ring system with three NÀCN cyanamide side arms connected to the carbon atoms of the ring.…”

Section: Introductionmentioning

confidence: 98%

Rare‐Earth Tricyanomelaminates [NH₄]Ln[HC₆N₉]₂[H₂O]₇⋅H₂O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy): Structural Investigation, Solid‐State NMR Spectroscopy, and Photoluminescence

Nag

Lotsch

Günne

et al. 2007

Chemistry A European J

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The rare-earth tricyanomelaminates, [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O (LnTCM; Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy), have been synthesized through ion-exchange reactions. They have been characterized by powder as well as single-crystal X-ray diffraction analysis, vibrational spectroscopy, and solid-state (1)H, (13)C, and (15)N MAS NMR spectroscopy. The X-ray powder pattern common to all nine rare-earth tricyanomelaminates LnTCM (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) indicates that they are isostructural. The single-crystal X-ray diffraction pattern of LnTCM is indicative of non-merohedral twinning. The crystals are triclinic and separation of the twin domains as well as refinement of the structure were successfully carried out in the space group P1 for LaTCM (LaTCM; P1, Z=2, a=7.1014(14), b=13.194(3), c=13.803(3) A, alpha=90.11(3), beta=77.85(3), gamma=87.23(3) degrees , V=1262.8(4) A(3)). In the crystal structure, each Ln(3+) is surrounded by two nitrogen atoms from two crystallographically independent tricyanomelaminate moieties and seven oxygen atoms from crystal water molecules. The positions of all of the hydrogen atoms of the ammonium ions and water molecules could not be located from difference Fourier syntheses. The presence of [NH(4)](+) ions as well as two NH groups belonging to two crystallographically independent monoprotonated tricyanomelaminate moieties has only been confirmed by subjecting LaTCM to solid-state (1)H, (13)C, and (15)N{(1)H} cross-polarization (CP) MAS NMR and advanced CP experiments such as cross-polarization combined with polarization inversion (CPPI). The (1)H 2D double-quantum single-quantum homonuclear correlation (DQ SQ) spectrum and the (15)N{(1)H} 2D CP heteronuclear-correlation (HETCOR) spectrum have revealed the hydrogen-bonded (N--HN) dimer of monoprotonated tricyanomelaminate moieties as well as H-bonding through [NH(4)](+) ions and H(2)O molecules. The structures of the other eight rare-earth tricyanomelaminates (LnTCM; Ln=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) have been refined from X-ray powder diffraction data by the Rietveld method. Photoluminescence studies of [NH(4)]Eu[HC(6)N(9)](2)[H(2)O](7)xH(2)O have revealed orange-red (lambda(max)=615 nm) emission due to the (5)D(0)-(7)F(2) transition, whereas [NH(4)]Tb[HC(6)N(9)](2)[H(2)O](7)xH(2)O has been found to show green emission with a maximum at 545 nm arising from the (5)D(4)-(7)F(5) transition. DTA/TG studies of [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O have indicated several phase transitions associated with dehydration of the compounds above 150 degrees C and decomposition above 200 degrees C.

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“…As might be expected for the double bond character of the C-N linkages, the distances also lie between the extremes found in calcium dicyanamide, Ca[N(CN) 2 ] 2 , which has bond lengths of 1.1152(7) and 1.1161(7) Å from C atoms to terminal N atoms and 1.321(7) and 1.335(6) Å to bridging N atoms in the [N(CN) 2 ] -anion. [34]. By comparison, the C-N bond length obtained from the refinement of the minor CaCN 2 phase in sample 1 is 1.223(1) Å which is identical within 1 r to the distances in the symmetric carbodiimide anion in 2 (and as compared to an N-N bond distance of 1.169 (15) in calcium azide) ( Table 4).…”

Section: Resultsmentioning

confidence: 90%

3D Nitride Frameworks with Variable Channel Sizes; Synthesis and Powder Neutron Diffraction Study of the Nitride Carbodiimdes, Ca4N2(CN2) and Ca11N6(CN2)2

2009

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The synthesis of powders of the calcium nitride carbodiimides, Ca 4 N 2 (CN 2 ) (1) and Ca 11 N 6 (CN 2 ) 2 (2) has been studied and the products characterised initially by powder X-ray diffraction. The latter phase (2) is unobtainable in pure bulk form and is always accompanied by the former compound. Nevertheless, definitive structures of the compounds were obtained from Rietveld refinements against time-of-flight powder neutron diffraction data. Each of the nitride carbodiimides are composed of Ca-N three dimensional networks built from edge-and vertexsharing NCa 6 octahedra arranged to create one-dimensional channels. The size of the channels is dependent on the Ca:C (host:guest) ratio and the larger channels in (1) are occupied by twice as many guest species as those in (2). Importantly, neutron diffraction data confirm that the identity of these guest species is carbodiimide (as opposed to isoelectronic azide), that neither the framework nor the channels therefore contain excess electrons and that the compounds are hence not ''nitride electrides'' as per the parent subnitride, Ca 2 N.

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Syntheses, Vibrational Spectroscopy, and Crystal Structure Determination from X-Ray Powder Diffraction Data of Alkaline Earth Dicyanamides M[N(CN)2]2 with M=Mg, Ca, Sr, and Ba

Cited by 61 publications

References 20 publications

Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)₂]₂

Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)₂]₂

Rare‐Earth Tricyanomelaminates [NH₄]Ln[HC₆N₉]₂[H₂O]₇⋅H₂O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy): Structural Investigation, Solid‐State NMR Spectroscopy, and Photoluminescence

3D Nitride Frameworks with Variable Channel Sizes; Synthesis and Powder Neutron Diffraction Study of the Nitride Carbodiimdes, Ca4N2(CN2) and Ca11N6(CN2)2

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Syntheses, Vibrational Spectroscopy, and Crystal Structure Determination from X-Ray Powder Diffraction Data of Alkaline Earth Dicyanamides M[N(CN)2]2 with M=Mg, Ca, Sr, and Ba

Cited by 61 publications

References 20 publications

Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)2]2

Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)2]2

Rare‐Earth Tricyanomelaminates [NH4]Ln[HC6N9]2[H2O]7⋅H2O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy): Structural Investigation, Solid‐State NMR Spectroscopy, and Photoluminescence

3D Nitride Frameworks with Variable Channel Sizes; Synthesis and Powder Neutron Diffraction Study of the Nitride Carbodiimdes, Ca4N2(CN2) and Ca11N6(CN2)2

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Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)₂]₂

Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)₂]₂

Rare‐Earth Tricyanomelaminates [NH₄]Ln[HC₆N₉]₂[H₂O]₇⋅H₂O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy): Structural Investigation, Solid‐State NMR Spectroscopy, and Photoluminescence