| 1. |
- Carlson, Stefan, et al.
(författare)
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On the structure of Na5Mn3F14
- 1995
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Ingår i: Zeitschrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 210, s. 489-493
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of the sodium manganese(III) fluoride compound, Na5Mn3F14, has been reinvestigated. The previous structure model, assuming the non-centrosymmetric space group symmetryPna21, has been transformed to the centrosymmetric symmetryPnam. Least squares refinements, based on new collected single crystal X-ray diffraction data, converged smoothly with the new structural model and yielded anR-value of 0.022. The general structural features described earlier, as the structural relations to the chiolite structure, still applies. However, the changed space group symmetry introduces new symmetry constraints to e.g. some of the coordination polyhedra in the structure.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Feuerbacher, M., et al.
(författare)
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The Samson phase, β-Mg2Al3, Revisited
- 2007
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Ingår i: Zeitschrift für Kristallographie. - 0044-2968. ; 222:6, s. 259-288
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Feuerbacher, Michael, et al.
(författare)
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The Samson phase, β-Mg2Al3, revisited
- 2007
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 222:6, s. 259-288
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Forskningsöversikt (refereegranskat)abstract
- The Al-Mg phase diagram has been reinvestigated in the vicinity of the stability range of the Samson phase, β-Mg2Al3 (cF1168). For the composition Mg38.5Al61.5, this cubic phase, space group Fd3̄m (no 227), a = 28.242(1) Å, V = 22526(2) Å3, undergoes at 214°C a first-order phase transition to rhombohedral β′-Mg2Al3, (hR293), a = 19.968(1) Å, c = 48.9114(8) Å, V = 16889(2) Å3, (i.e. 22519 Å3 for the equivalent cubic unit cell) space group R3m (no 160), a subgroup of index four of Fd3̄m. The structure of the β-phase has been redetermined at ambient temperature as well as in situ at 400°C. It essentially agrees with Samson's model, even in most of the many partially occupied and split positions. The structure of β′-Mg 2Al3 is closely related to that of the β-phase. Its atomic sites can be derived from those of the β-phase by group-theoretical considerations. The main difference between the two structures is that all atomic sites are fully occupied in case of the β′-phase. The reciprocal space, Bragg as well as diffuse scattering, has been explored as function of temperature and the β- to β′-phase transition was studied in detail. The microstructures of both phases have been analyzed by electron microscopy and X-ray topography showing them highly defective. Finally, the thermal expansion coefficients and elastic parameters have been determined. Their values are somewhere in between those of Al and Mg.
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| 7. |
- Gemmi, Mauro, et al.
(författare)
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Scanning reciprocal space for solving unknown structures : energy filtered diffraction tomography and rotation diffraction tomography methods
- 2013
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 228:1, s. 51-58
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Tidskriftsartikel (refereegranskat)abstract
- Structure solutions of CaFe2O4 from energy filtered and unfiltered precession electron diffraction tomography and rotation electron diffraction tomography data, collected on two different microscopes, are reported. The collected data are analysed with three available software packages (ADT3D, PETS and EDT-PROCESS) and the obtained results are compared. In all cases the structure solution is successfully achieved. Energy filtered precession electron diffraction tomography, performed here for the first time, gives sharper diffraction peaks and less background compared to the unfiltered data and the final recovered model is closer to the X-ray refinement. Simultaneously the first crystal structure solution obtained from the rotation electron diffraction tomography data is reported.
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| 8. |
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| 9. |
- Karmakar, Anirban, 1983, et al.
(författare)
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A two-dimensional metal organic network with 1,3,5-benzenetricarboxylate and cobalt (II) ions: synthesis, structure and topology
- 2013
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Ingår i: Zeitschfrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 228:7, s. 330-334
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Tidskriftsartikel (refereegranskat)abstract
- We herein report the synthesis and structure of a two dimensional (2D) metal-organic coordination polymer (or metal-organic network) which extends in two dimensions via Co2+ and 1,3,5-benzenetricarboxylate ions. The hydrothermal reaction of (2R,2'R,2 '' R)-2,2',2 ''-(benzenetricarbonyltris(azanediyl))tripropanoic acid (parent ligand) with cobalt nitrate in the presence of pyridine lead to the decomposition of the parent ligand producing 1,3,5-benzenetricarboxylate, which in turn reacted with cobalt ions to afford a 2D network [Co-1.5(BTC3-) center dot (pyridine)(3) center dot (H2O)](H2O)(0.26) center dot (MeOH) (1). This network was characterized by single crystal X-ray diffraction and IR spectroscopy. The topological study indicated that the framework is a 3,4-connected binodal net.
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| 10. |
- Karpus, Vytautas, et al.
(författare)
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Optical response of si-ZnMgHo quasicrystal
- 2009
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Ingår i: ZEITSCHRIFT FUR KRISTALLOGRAPHIE. - : Walter de Gruyter GmbH. - 0044-2968. ; 224:1-2, s. 39-41
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Tidskriftsartikel (refereegranskat)abstract
- The results of room-temperature optical study of single-grain simple icosahedral ZnMgHo quasicrystals are presented. The dielectric function epsilon(omega) of the quasicrystals was measured by spectroscopic ellipsometry technique in the spectral range of 0.1 - 7 eV. The si-ZnMgHo optical response is a superposition of the free-electron Drude-type contribution and that of the interband transitions. The experimental epsilon(omega) spectra are well simulated within a framework of the band structure hypothesis. The deduced parameters of the si-ZnMgHo electron energy spectrum are close to their values determined previously in an analysis of the si-ZnMgHo photoemission data.
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| 11. |
- Klingstedt, Miia, et al.
(författare)
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Exit wave reconstruction from focal series of hrtem images, single crystal xrd and total energy studies on sbxwo3+y (x similar to 0.11)
- 2012
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968 .- 2194-4946. ; 227:6, s. 341-349
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Tidskriftsartikel (refereegranskat)abstract
- A new tungsten bronze in the Sb-W-O system has been prepared in a solid state reaction from Sb2O3, WO3 and W metal powder. The average structure was determined by single crystal X-ray diffraction. SbxWO3+y (x similar to 0.11) crystallizes in the orthorhombic space group Pm2(1)n (no. 31), a = 27.8135(9) angstrom, b = 7.3659(2) angstrom and c = 3.8672(1) angstrom. The structure belongs to the (n)-ITB class of intergrowth tungsten bronzes. It contains slabs of hexagonal channels formed by six WO6 octahedra. These slabs are separated by three layers of WO6 octahedra that are arranged in a WO3-type fashion. The WO6 octahedra share all vertices to build up a three-dimensional framework. The hexagonal channels are filled with Sb atoms to similar to 80% and additional 0 atoms. The atoms are shifted out of the center of the channels. Exit-wave reconstruction of focal series of high resolution-transmission-electron-microscope (HRTEM) images combined with statistical parameter estimation techniques allowed to study local ordering in the channels. Sb atoms in neighbouring channels tend to be displaced in the same direction, which is in agreement with total energy calculations on ordered structure models, but the ratio of the occupation of the two possible Sb sites varies from channel to channel. The structure of SbxWO3+y exhibits pronounced local modulations.
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| 12. |
- Langer, Vratislav, 1949, et al.
(författare)
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Crystal and electronic structure of aqua(N-salicylidene-methylester-L-glutamato)Cu(II) monohydrate
- 2004
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Ingår i: Zeitschfrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 219:2, s. 112-116
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Tidskriftsartikel (refereegranskat)abstract
- The absolute structure of the title compound, CuNC13H17O7, has been determined. The crystal structure consists of the molecular units Cu(N-sal-5-met-L-glu)(H2O) connected by a three-dimensional network of hydrogen bonds. The coordination polyhedron in the complex is approximately square-pyramidal with a pentacoordinated Cu(II) atom. The base of the pyramid is formed by nitrogen and oxygen atoms belonging to the molecule, while the apex of the pyramid contains a weakly bonded oxygen atom of the carboxylic group of another molecule. The B3LYP/SVP method and basis set in Gaussian98 was used for quantum chemical calculation of the nature of CuX (X = O, N) bonds. While the calculated dissociation energy of the weakly bonded crystalline water is only 17.2 kJ/mol, the bonding energy of the water molecule coordinating to the Cu atom is 62.3 kJ/mol.
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| 13. |
- Liu, Leifeng, et al.
(författare)
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Structure determination of [3Fe2S] complex with complicated pseudo-merohedric twinning
- 2012
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 227:4, s. 221-226
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Tidskriftsartikel (refereegranskat)abstract
- A route of solving crystal structures from complicated pseudo-merohedric twinning crystals was described. The structure of a [3Fe2S] complex was solved and refined in the space group of P42/n to R1 factor of 0.1789. Consequently, by deleting one of the two disordered groups in the structure, a space group of Aea2 for the absolute structure was found. The new absolute structure with four twinning components was refined to R1 about 0.1171. At the final stage, the disorder was again added to the structure. The structure in space group Aea2 with both twinning and disorder was refined to R1 of 0.0722, which implies the special structure feature.
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| 14. |
- Lundberg, Daniel, et al.
(författare)
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On the coordination chemistry of the dimercury(I) ion with O-donor ligands
- 2012
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Ingår i: Zeitschrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 227, s. 683-687
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Tidskriftsartikel (refereegranskat)abstract
- An overview of published crystalline dimercury(I) hydrates, solvates, and complexes/compounds with other O-donor ligands shows that there is virtually no correlation between the Hg-Hg bond distance and the overall Hg-O bonding conditions. Additionally, many structures feature a different Hg-O bonding situation for the different halves of the dimercury(I) ion, Hg22+. To supplement these findings, the crystal structures of the perchlorate salts of hydrated and dimethylsulfoxide (dmso) solvated mercury(I), [Hg2(H2O)2](ClO4)2 (1) and [Hg10(OS(CH3)2)16](ClO4)10 (2), respectively, have been determined by single crystal X-ray diffraction. In compound 1, the perchlorate ions act as bridges between the almost linear [Hg2(H2O)2]2+ units forming infinite chains. The Hg-Hg bond distance is 2.500(1) Å and the Hg-O distance to the water molecule is 2.231(19) Å, and with six additional much weaker Hg-O bonds to bridging perchlorate oxygens in the range 2.78-3.15 Å. Compound 2 consists of five separate entities where the [Hg-Hg]2+ units are solvated and bridged by dmso oxygens. These entities form chains through much weaker bridging perchlorate ions at longer distances, 3.0-3.3 Å, with a few remaining perchlorate ions isolated in the lattice. The mean Hg-Hg bond distance is 2.500(1) Å, while the Hg-Odmso bond distances are in the range of 2.15-2.92 Å. The dmso molecules display three kinds of coordination, strong κO-terminal, medium μ2O-bridging, or medium + weak μ3O-bridging, depending on which mercury(I) ion(s) in the entity they coordinate to.
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| 15. |
- Nimmermark, Anders, 1971, et al.
(författare)
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Metal-ligand bond lengths and strengths: are they correlated? A detailed CSD analysis
- 2013
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Ingår i: Zeitschfrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 228:7, s. 311-317
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Konferensbidrag (refereegranskat)abstract
- Structure data on metal-alkoxides, metal-alcohol, metal-carboxylates, metal-carboxylic acid, metal-azolate and metal-azole coordination compounds from the Cambridge Structural Database (CSD) were analysed in terms of bond lengths. In general the anionic ligands form shorter metal-ligand bonds by about 0.02-0.05 angstrom compared to neutral ligands, a clear indication of a charge contribution to the bonding interactions. This small difference is not, however, deemed as sufficient to generate two distinct classes of metal-ligand bonding. Instead, the anionic ligands can be viewed as having "charge assisted" metal-ligand bonding, corresponding to the same term used for "charge-assisted hydrogen bonding".
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| 16. |
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| 17. |
- Rashidi-Ranjbar, Parviz, et al.
(författare)
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Host-guest interaction in propeller-shaped molecules. Part one : Single crystal X-ray analysis of benzylidene-1,1 '-bis-2-naphthol solvent cocrystals
- 2009
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 224:10, s. 499-505
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Tidskriftsartikel (refereegranskat)abstract
- The structures of cocrystals of benzylidene-1,1'-bis-2-naphthol with methanol and ethanol have been studied by single crystal X-ray diffraction and H-1-NMR spectroscopy. The cocrystal structures are stabilized by intra-and inter-molecular hydrogen bonds with the stoichiometry of a 1 : 1 host: guest. The competition experiment in the solid-liquid biphasic system between pair of guests revealed that methanol is preferentially enclathrated over ethanol in all mole fractions.
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| 18. |
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| 19. |
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| 20. |
- Schellenberg, Inga, et al.
(författare)
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Structure and properties of the 5.5 K antiferromagnet EuAu2Ge2
- 2011
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Ingår i: Zeitschrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 226:3, s. 214-218
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Tidskriftsartikel (refereegranskat)abstract
- A well crystallized sample of EuAti(2)Ge(2) was synthesized by arc-melting of the elements. The structure was refined on the basis of single crystal X-ray diffractometer data: ThCr2Si2 type, 14/mmm, a = 447.3(1), c = 1034.0(4) pm, wR2 = 0.0575, 148 F-2 values and 9 variables. The gold atoms have tetrahedral germanium coordination (261 pm Au-Ge). These AuGe4/4 tetrahedra share four common edges, leading to layers which are connected via Ge-Ge bonds (247 pm). The europium atoms fill cages of coordination number 16 within the [Au2Ge2](delta-) polyanion. Temperature dependent susceptibility measurements show a magnetic moment of 7.79(1)mu(B)/formula unit. Together with the Eu-151 Mossbauer spectroscopic data (isomer shift of -11.43 mm/s at 77K), the magnetic data point to stable divalent europium. EuAu2Ge2 orders antiferromagnetically at T-N1 = 5.5(1) K, followed by a spin-reorientation at T-N2 = 3.5 K. A metamagnetic step occurs around 20 kOe in the 4 K magnetization isotherm.
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| 21. |
- Smrcok, Lubomir, et al.
(författare)
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Intramolecular hydrogen bond and proton transfer in 3-(2-benzimidazolylthio)-2,4-pentanedione. Crystallographic evidence and theoretical calculations
- 2002
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Ingår i: Zeitschfrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 217:5, s. 217-222
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Tidskriftsartikel (refereegranskat)abstract
- Crystal structure of the title compound is orthorhombic, Pbca, a=7.8689(2)Å, b=9.6519(3)Å, c=31.3579(9)Å. The structure was solved by direct methods and refined by a full-matrix least squares procedure to final R (all)=0.0682 for 2853 unique diffractions merged from 24459 measured at 183(2)K. The molecule is formed by two planar moieties joined through an atom of sulphur. The short intramolecular O...O contact is 2.430(2)Å, the intramolecular hydrogen bond is slightly asymmetric. Theoretical ab initio calculations done at B3LYP/SVP and ONIOM(MP2/SVP:B3LYP/SVP) levels showed that the experimental geometry of pentanedione pseudoring is close to the geometry corresponding to a transition state on the asymmetric potential energy curve. Calculated energy difference between two minima is only 4.72 kJ/mol and the energy barrier 6.02 kJ/mol, which agrees well to ~6.6kJ/mol found in microwave spectroscopic study of malonaldehyde.
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| 22. |
- Smrcok, L'ubomir, et al.
(författare)
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1,4-diazabicyclo[2.2.2]octane-1,4-diium dihydrogen phosphate monohydrate from X-ray and neutron data
- 2009
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 224:3, s. 174-178
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Tidskriftsartikel (refereegranskat)abstract
- The three-dimensional skeleton of the structure of the title compound is formed by the chains of the hydrogen phosphate units running approximately parallel to the c-axis. The units are coupled to the chains by three types of hydrogen bonds: strong symmetric O-H-O (O center dot center dot center dot O = 2.424(4) and 2.425(4) angstrom) and the moderate P-O-H center dot center dot center dot O-P and P-O center dot center dot center dot(H2O)center dot center dot center dot O-P, respectively. Molecules of the doubly protonated 1,4-diazabicyclo[2.2.2]octane moieties are placed in the voids and in addition for electrostatic interactions they are also hydrogen bonded to the chains of PO4 tetrahedra. The DC conductivity measured at the room temperature along the b-axis is very low (approximate to 7 x 10(-11) S cm(-1)), while in the perpendicular plane it is for more than two or three orders higher and the nonlinear current vs. potential dependence was registered.
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| 23. |
- Sun, Junliang, et al.
(författare)
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Structure determination of the zeolite IM-5 using electron crystallography
- 2010
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 225:03-feb, s. 77-85
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the complex zeolite IM-5 (Cmcm, a = 14.33(4) angstrom. b = 56.9(2) angstrom, c = 20.32(7) angstrom) was determined by combining selected area electron diffraction (SAED), 3D reconstruction of high resolution transmission electron microscopy (HRTEM) images from different zone axes and distance least squares (DLS) refinement. The unit cell parameters were determined from SAED. The space group was determined from extinctions in the SAED patterns and projection symmetries of HRTEM images. Using the structure factor amplitudes and phases of 144 independent reflections obtained from HRTEM images along the [100], [010] and [001] directions, a 3D electrostatic potential map was calculated by inverse Fourier transformation. From this 3D potential map, all 24 unique Si positions could be determined. Oxygen atoms were added between each Si-Si pair and further refined together with the Si positions by distance-least-squares. The final structure model deviates on average 0.16 angstrom for Si and 0.31 angstrom for O from the structure refined using X-ray powder diffraction data. This method is general and offers a new possibility for determining the structures of zeolites and other materials with complex structures.
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| 24. |
- Wallentin, Carl-Johan, et al.
(författare)
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Chirality, a never-ending source of confusion
- 2009
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Ingår i: Zeitschrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 224:12, s. 607-608
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this Discussion a few points of confusion concerning chirality are clarified. The term chirodescriptive is proposed for such space groups that lack inversion centres, reflection planes, glide planes or rotary-inversion axes and thus can contain enantiopure, chiral objects. It is pointed out that chiral compounds can (and often do) crystallise in non-chirodescriptive space group when they occur as racemates and in such cases there is no incompatibility between chirality and mirror planes or centres of inversions. We also propose the term raceomorphism to describe the relationship between a conglomerate and a collection of racemic crystals of the same compound.
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| 25. |
- Willhammar, Tom, et al.
(författare)
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Stacking disorders in zeolites and open-frameworks - structure elucidation and analysis by electron crystallography and X-ray diffraction
- 2013
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 228:1, s. 11-27
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Forskningsöversikt (refereegranskat)abstract
- Intergrowth and stacking disorders are often found in minerals and synthetic zeolites and inorganic open-frameworks. Structure elucidation of stacking disorders in these materials have been difficult and structure solution of stacking disorders in unknown zeolites and open-frameworks has been challenging. There exist no standard methods for structure analysis of such disordered materials. In this review we present various stacking disorders and intergrowth in a number of representative zeolite families containing stacking disorders. These include zeolite beta, SSZ-26/SSZ-33, ITQ-39, ABC-6, ZSM-48, SSZ-31, UTD-1, faujasite FAU/EMT, pentasil ZSM-5/ZSM-11, ITQ-13/ITQ-34, ITQ-22/ITQ-38 etc. Stacking disorders in open-frameworks containing mixed coordinations, including titanosilicates ETS-10 and ETS-4, and the silicogermanate SU-JU-14 are also described. Various crystallographic methods used for solving disordered structures are summarized. The methods include powder X-ray diffraction (PXRD), electron diffraction, high resolution transmission electron microscopy (HRTEM), and single-crystal X-ray diffraction. Examples of model building combined with simulations of PXRD and single crystal X-ray diffraction to verify the structure models are given.
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| 26. |
- Yamada, Tsunetomo, et al.
(författare)
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In-situ high-pressure X-ray diffraction on the Zn6Sc 1/1 periodic cubic approximant to a quasicrystal
- 2014
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 229:3, s. 230-235
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Tidskriftsartikel (refereegranskat)abstract
- The Zn6Sc 1/1 cubic approximant to a quasicrystal has been studied in-situ at high pressures by single-crystal X-ray diffraction. This phase can be described as a bcc packing of Tsai-type icosahedral clusters whose center is occupied by a disordered Zn-4 tetrahedron. At ambient pressure the Zn6Sc undergoes a structural phase transition at 159 K to a monoclinic superstructure in which the Zn-4 tetrahedra are orientationally ordered along the [101] direction of the high-temperature bcc phase. In the pressure range up to 35 GPa, two new superstructures have been observed. The second phase corresponds to a four-fold pseudo cubic superstructure, i.e. a very large unit cell with a lattice parameter of about 5.5 nm. The resulting pressure-temperature phase diagram is different from that of Cd6Yb, which was reported by Watanuki et al. (2006).
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| 27. |
- Yao, Qingxia, et al.
(författare)
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SUMOF-5 : a mesoporous metal-organic framework with the tbo topology built from the dicopper paddle-wheel cluster and a new tritopic linker
- 2013
-
Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 228:7, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- A mesoporous metal-organic framework Cu-3(PTB)(2)(H2O)(3) center dot guest (denoted as SUMOF-5) has been synthesized using a new tritopic linker pyridine-2,4,6-tribenzoic acid (H3PTB). SUMOF-5 is cubic with the space group Fm (3) over barm and a = 47.272(3) angstrom. The framework is built of the dicopper paddle-wheel secondary building unit (SBU) [Cu-2(OOC)(4)(H2O)(2)] and contains two different cavities of 1.22 and 2.33 nm in diameter, respectively. The framework topology follows the (3,4)-connected tbo net, and can be regarded as an extended version of Cu-3(BTC)(2)(H2O)(3) center dot guest (HKUST-1, BTC = benzene tricarboxylate). The structure of SUMOF-5 is compared to other MOFs built from dicopper paddle-wheels and tritopic linkers. SUMOF-5 has permanent porosity with a Langmuir surface area of 1733 m(2)/g and is stable in various organic solvents, which makes this material potentially useful as a crystalline carrier for loading molecular catalysts or drugs.
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| 28. |
- Zhang, Daliang, et al.
(författare)
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Collecting 3D electron diffraction data by the rotation method
- 2010
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Ingår i: Zeitschrift fur Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 225:2-3, s. 94-102
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Tidskriftsartikel (refereegranskat)abstract
- A new method for collecting complete three-dimensional electron diffraction data is described. Diffraction data is collected by combining electron beam tilt at many very small steps, with rotation of the crystal in a few but large steps. A number of practical considerations are discussed, as well as advantages and disadvantages compared to other methods of collecting electron diffraction data.
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| 29. |
- Öhrström, Lars, 1963, et al.
(författare)
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Network topology approach to new allotropes of the group 14 elements
- 2013
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Ingår i: Zeitschfrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 228:7, s. 343-346
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Tidskriftsartikel (refereegranskat)abstract
- The network topology approach has been a major driving force in the search for new metal-organic frameworks and coordination networks. In this work we demonstrate how this method not only generated the recently described "T12" allotrope of the group 14 elements, identical to the cdp topology found in the structure of CdP2, but also a number of other candidate structures for polymorphs of these network-forming elements. Data on such network structures have been compiled since the 1950's and is readily accessible through several internet based systems. The usefulness of topology for the classification of these allotropes is emphasised.
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