Triclinic polymorph

Olanzapine appears to exist in at least five polymorphic forms, and the structure of Form II has been reported [32]. Two molecules form centrosymmetric dimmers stabilized by a series of C—H - rc interactions, and the dimmers are connected by a system of intermolecular N—C—and C—H S hydrogen bonds. The structure of a monoclinic polymorph of isoxsuprine hydrochloride has been reported [33], The molecular conformation existing in the new monoclinic polymorph was found to be very similar to that existing in the known triclinic polymorph. 

The structure of a second polymorph of 4,5-diphenyl- lH-imidazole has been discussed, with the new form exhibiting significantly different phenyl/imidazole dihedral angles and mode of crystal packing relative to the known form [53], A new triclinic polymorph of 1,4-dibenzoyl-butane was found, differing from the monoclinic form in the torsional angles of the central chain [54], Two polymorphs of diphenyl-(4-pyridyl)methyl methacrylate have been found, where the molecules in the two forms contain weak C—H— n and C—H O/N contacts that lead to the existence of different conformations [55]. 

Thus, the triclinic polymorph formed a chain of pairs of trinudear units. The trinudear complexes associated through interactions at 3.2201(9) A and the interactions between pairs of molecules are longer, 3.583(12). 

In contrast to the previous case, only the triclinic polymorph was luminescent at room temperature, displaying a single emission at 654 nm (exc. 326 nm). The authors assigned this luminescence to the existence of shorter gold-gold contacts between adjacent trinuclear molecules. This result is also striking since it displayed a red shift... 

Figure 6.17 Drawing of the triclinic polymorph of [Au3(n-PentN = COCH3)3],...

Steinfink, H., 1958b. The crystal structure of chlorite, 2. A triclinic polymorph. Acta Cryst., 11 195-198. 

Fig. 15 Comparisons of the emission and excitation spectra of the polymorphs of Au 3(MeN = COMe)3 at 298 K A hexagonal polymorph B triclinic polymorph and C monoclinic polymorph. From [41]...

Fig. 19 The structure of the triclinic polymorph of Au MeN = COMe)3 showing A the molecular structure and B the intermolecular contacts. Only the locations of the gold(I) ions are given in B. From [41]...

Fig. 6.23 Normal incidence polarized reflection spectra of the two forms molecule 6-XVII (R = Et, R = OH). For each crystal modiflcation there are two spectra measured with the light polarized along each of the two directions (the so-called principal directions), as indicated in the upper right hand corner, which also shows the projection of the molecule(s) onto the crystal face studied, (a) Triclinic polymorph, (100) face (b) monoclinic polymorph, (100) face. (From Tristani-Kendra and Eckhardt 1984, with permission.)...

Figure 24. The structure of orthowalpurgite, Bi404[(U02XAs04)2](H20)2, projected along [010], at left projected along [100], at right, after [103]. Bismuth-centered distorted octahedra are striped. The triclinic polymorph walpurgite exhibits a very similar structure [103].

Structural and Physical Aspects. - The stability of the various conformers of the phosphines oxides (269)- 211) has received theoretical consideration. A new triclinic polymorph of triphenylphosphine sulfide has been structurally characterised, together with a related triclinic polymorph of triphenylphos-phine. Two reports of the solid state crystal structure of the phenolic phosphine oxide (272) have appeared. A crystallographic study has confirmed that the product of electrochemical oxidation of o-diphenylphosphinoben-zenethiol is the disulfide-bridged bis(phosphine oxide) (273). Solid-state structural studies of the dioxides (274), the (i )-(-I-)-isomer of (275), 1-hexynyl(diphenyl)phosphine oxide,tribenzylphosphine oxide, and tris(t-butyl)phosphine selenide," have also been reported. 

A new unsolvated form of pyrazine-2,3-dicarboxylic acid 100 was subjected to X-ray crystallography <04AX(E)1305>, as was an orthorhombic polymorph of A,A -bis(2-pyridyimethyl)pyrazine-2,3-dicarboxamide 101 <04AX(E)210> and two triclinic polymorphs of... 

The crystallographic data for the two forms are summarized in Table 11, while the crystal packing and molecular conformations are illustrated in Fig. 7. The molecule was found to adopt a planar conformation in the triclinic phase, but in the orthorhombic phase the phenyl rings were rotated by 24.8° about the N-phenyl and CH-phenyl bonds. Both structures may be described as being composed of blocks of molecules between two neighboring parallel planes. For the triclinic polymorph the blocks are stacked along the Z>-axis, while in the orthorhom-... 

There is a growing interest in the use of Raman spectroscopy for studying polymorphism and pseudopolymorphism [27]. The Raman technique has recently been used to distinguish two triclinic polymorphs of terephthalic acid [120] and, in combination with IR spectroscopy, to study the conformational polymorphism of 1-bromopentane [121]. 

The systems 5-amino-2-methoxypyridine ester amide of squaric acid ethyl ester and 2-[5,5-dimethyl-3-[2-(2,4,6-trimethoxyphenyl)vinyl]cyclo-hex-2-enylidene] malono-nitrile triclinic polymorph differ from the other two groups of similarity and occupy the position of outliers rather than belonging to a separate group. They indicate quite different intensities and impacts of the input parameters, and should be considered as individual cases with respect to their output signal and response to the experimental conditions. 

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