Orthorhombic space group

The iron-thiolato complex (Me4N)2[Fe4S4(SC6H5)4] crystallizes in this space group with Z = 4, and the asymmetric unit consists of two Me4N+ cations and 

Hexachlorocyclophosphazene, (PNC b, has Z = 4. Space group Pnma (no. 62) has special positions of site symmetry I and m clearly 1 can be ruled out, and the molecule has a mirror plane passing through a PCI2 group and an opposite N atom in the ring. The molecular and crystal structure are shown in Fig. 9.6.10. 

The Dewar benzene derivative l,8, 3,5-naphtho[5.2.2]propella-3,8,10-triene, Ci.sHu. also has Z = 4, and a crystallographic mirror plane passes through the central naphthalene C-C bond and the midpoints of the bonds C(8)-C(8 ), C(9)-C(9 ) and C(10)-C(10/). The measured bond lengths in the strained ring system and crystal structure are shown in Fig. 9.6.11. 

If the formula of orthorhombic black phosphorus is written simply as P, then Z = 8. The special positions of space group Cmca are 4(a) 2/m, 4(b) 2/m, 8(c) 1,8(d) 2, 8(e) 2, 8(f) m, and general position 16(g) 1. The independent P atom actually is located in 8(f), generating a continuous double-layer structure, which is a heavily puckered hexagonal net in which each P atom is covalently bound to three others within the same layer. In Fig. 9.6.12, two puckered layers in 

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Chatani42,43 has shown that if the hexagonal inclusion compounds are cooled many of them undergo a reversible transformation into a low-temperature form with the orthorhombic space group These phase transitions take place over a... 

Yet another type of canal structure has been reported for the urea inclusion compound of 1,4-dichlorobutane 51). Even though the canals are pseudo-hexagonal in dimension, there is a significant difference in their symmetry. The host lattice is orthorhombic, space group Pbcn. The difference lies in the directions of the six pseudo-3j helices of host molecules around the walls of each canal the sequence is cyc/o-RRRLLL, as opposed to cyc/o-RRRRRR in the hexagonal inclusion compounds and cvc/o-RLRLRL in the rhombohedral. This orthorhombic host structure probably occurs also in the urea inclusion compounds with 1,5-dichloropentane and 1,6-dibromohexane 51). 

DCA forms canal inclusion compounds, known as choleic acids, which most frequently have the orthorhombic space group P212121, or less frequently Pl l. In such crystals the DCA molecules hydrogen bond to each other to form an extended bilayer structure, thereby creating a hydrophobic canal between adjacent bilayers. The guest molecules present in these canals therefore tend to be non-polar or moderately polar molecules such as aromatic compounds, alkenes, ketones and certain carboxylic acids 92). Since the bilayers are held together only by van der Waals forces the canals are able to adopt different dimensions to accommodate the variety of... 

Unsolvated tri-o-thymotide (TOT) (20) crystallises in the orthorhombic space group Pna21 101 102) but forms inclusion compounds with an extremely wide range of organic materials (> 100) in different arrangements 103). 

This helical arrangement of amylose, known as the V-form, may be precipitated from certain solutions (e.g. in butanol or DMSO) of amylose. Either hydrated (Vh-) or anhydrous (Va-) amylose absorbs I2 vapour to produce the blue compound with the necessary I" being produced in situ. Alternatively the compound may be formed from iodine-iodide mixtures in solution which allows the V-form to be produced and stabilised as the polyiodide compound 141 The compound was reported 142) to have the orthorhombic space group 7>212121. 

Crystalline CrBr2-6py slowly loses pyridine after a few days when confined in an x-ray capillary. The crystals are orthorhombic, space group Pmma or Pmcv or Pma2, with a = 9.89, 6 = 15.4, and c = 18.8. With z — 4, the calculated density is 1.6 g./cm.3... 

Dicyanofuroxan (3,4-dicyano-l,2,5-oxadiazole 2-oxide), the precursor to the NCCNO (see structure 11) species, has been studied in the solid and gas phases to obtain both structural and electronic information. The solid-state structure determined by X-ray diffraction gives an orthorhombic space group PnaZ, with a= 10.2578(14), b = 10.8818(12), and c= 10.2259(15) A. There are two independent molecules with similar geometries in the asymmetric unit. The gas-phase molecule was characterized by Hel photoelectron, Hel and HLtti(3i7 photoionization, and IR spectroscopy. The... 

The ion-triple 37 crystallizes in the orthorhombic space group P2i2i2i. The dianion in 37 is remarkable, since the hydridic H atoms are evidently better donors toward Li ions than the As centers, and the DME molecule functions rather surprisingly as a monodentate ligand (Fig. 29) (07). The Al-As distances are unremarkable and in the range of other chair-shaped ARAS3 frameworks (03). 

M11AI3 0PI6O-M11AI3 type is orthorhombic, space group Pnma, a = 1480pm, b = 1240 pm, c = 1260 pm). 

CrB, oS8, structural type Orthorhombic, space group Cmcm, N. 63. 

CeCu2vs. KHg2 the original structural description as oil 2-CeCu2 type CeCu2, body-centred orthorhombic, space group Imma, N. 74. 

KHg2, body-centred orthorhombic, space group Imma, N. 74. 

Co2Si (PbCl2), oP12, and TiNiSi, oP12, structural types. Orthorhombic, space group Puma, N. 62. 

TiSi2> oF24, structural type Face-centred orthorhombic, space group Fddd, N. 70. 

The (3TiCu3 structure is orthorhombic, space group Pmmn, N. 59. 

Tm5Sb2Si2 Orthorhombic, space group Cmca, N. 64 (oS36-Eu5As4-derivative structure). 

The orthorhombic point symmetiy 222 comprises three intersecting twofold axes perpendicular to each other. It applies to the commonly observed orthorhombic space group P2,2,21. 

A positive evidence for a true cr-bonded organolanthanide complex is presented by Cotton et at. (32) in a crystal structure analysis of the anionic complex [Lu(III)-tetrakis-2,6-dimethylphenyl] . This anion crystaJUizes as [Li(I)-tetrakis-tetra-hydrofuran]+ salt, [Li(C4HgO)4]+ [Lu(C8H9)4] , in orthorhombic space group (P2i2i2i) with a = 15.093, 6 = 15.265 and c = 19.959 A and four formula units per unit cell. 

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