Single crystal analysis

The indazole alkaloid Nigellidine (269) (Scheme 88) which was described as a zwitterion, was detected in the seeds of Nigella saliva L. (Ranunculaceae) (95TL1993), which is an erect annual plant found in South Asia and is widely cultivated. The seeds are commonly believed to have carminative, stimulatory and diaphoretic properties (75PHA2759). An X-ray single crystal analysis was performed on the methyl chloride. It is... 

In the as-synthesized MFI-crystals the tetrapropylammonium (TPA) ions are occupying the intersections between the straight (parallel) and the sinusoidal channels of the zeolite, thus providing an efficient pore filling. The detailed structure of as-synthesized MFI-TPA has been elucidated by X-ray single crystal analysis (ref. 3). Also the combination tetrabutyl-Ztetraethylammonium can be applied as template in MFI-synthesis. A 1 1 build-in is found then (Fig. 1). When only tetrabutylammonium is available as template, the MEL (ZSM-11) lattice is formed with another distance between the channel intersections. 

X-ray single crystal analysis Data collection. Siemens SMART IK CCD. Diffractometer. Data collection by SMART (Siemens, 1995) cell refinement SMART data reduction SAINT (Siemens, 1995) program(s) used to solve structure SHELXS97 (Sheldrick, 1997) program(s) used to refine structure SHELXL97 (Sheldrick, 1997) molecular graphics XP in SHELXTL (Sheldrick,... 

We could identify that both phosphorous atoms stay coordinated to the metal (PP coupling among metal at 40,5 Hz). Crystallization of the complex in CHCls/hexane allowed an x-ray single crystal analysis that clearly demonstrates the coordination chemistry as shown above. 

For ruthenium, special precursors are required to synthesize defined bidentate diphosphine complexes. With Taniaphos for instance, it is possible to synthesize such complexes starting from unusual rathenium(ll) species. The complexes were characterized by NMR and single crystal analysis. 

Additionally, the authors wotrld like to thank Dr. Bats (University of Frankfurt am Main, Germany) for preparing x-ray single crystal analysis. 

The structure of dimer XI (X, where n = 2), obtained by x-ray single crystal analysis (Figure 1), shows that the desired skeletal stabilization based upon 1,4- condensation units has been achieved. 

Of special interest (see Table II) is the structure of compound XVI, obtained in a reaction with thermodynamic control, and its sulfide (XVII), as both molecules contain the P—H bond. Infrared, Raman, and NMR studies as well as dipole moment measurements showed that the P—H bond was axial in these compounds. In some cases the conclusions of NMR and dipole moment studies were verified by X-ray single-crystal analysis. 

N-benzyladamantyl-2-imines, and 2-methyleneadamantanes were studied (352, 353). In particular, X-ray single-crystal analysis confirmed the configuration of the oxathiazoline 185, resulting from the favored attack of nitrile oxide on the 5-fluoroadamantane-2-thione. 2-Silyl-substituted oxathiazole 186 was synthesized by the 1,3-dipolar cycloaddition reaction of phenyl triphenylsilyl thioketone with 4-chlorobenzonitrile oxide (354). 

Single crystal analysis of polysilanes is rare, since the structural variations in polymer samples usually preclude the formation of crystals of sufficient quality and size, although there are a few reports. The structure of l,6-bis[(i )-2-phenylpropyl]dodecapropylhexasilane, 5(R), with terminal chiral groups has been reported 15 the conformation is M-screw sense all-transoid with backbone dihedral angles in the range —172° to —177°, and was described as a 157 helix the structure is shown in Figure 21. 

In order to allow for a closer approach of the boron centers, the introduction of flat cyclic boryl moieties with reduced steric hindrance has also been pursued. Thus, the reaction of 26 with 9-chloro-9-borafluorene and 5-bromo-10,l 1-di-hydrodibenzo[b,f]borepin resulted in the formation of diboranes 31 and 32 which bear two different boryl moieties at the pen-positions of naphthalene (Scheme 13). " These diboranes have been characterized by multinuclear NMR spectroscopy and X-ray single-crystal analysis. In 31, the boron center of the borafluorenyl moiety is 7i-coordinated by the zp o-carbon of a mesityl group with which it forms a contact of 2.730(3) A (Fig. 8). As a result of this interaction, the boron center involved in this contact is slightly pyramidalized (Xangie = 355.7°). In the case of 32 (Fig. 9), the distance between the boron center of the boracylic moiety and the zpio-carbon of... 

Four monothioimides la-d were investigated for their solid-state photochemical behavior. All monothioimides except lb, which did not give available crystals, were subjected to X-ray single crystal analysis. Figure 1 shows the Ortep drawing of la (Fig. la), Ic (Fig. lb), and Id (Fig. Ic). 

Recrystallization of thioamides 24f-h gave colorless or slightly yellow prismatic crystals [49]. All three thioamides were subjected to X-ray single crystal analysis, and it was revealed that they prefer the same conformation 24-1 in which a benzyl group was placed close to the thiocarbonyl group, the same as the major isomer in solution. The alkenyl double bonds are perpendicular to the thioamide group, and twist in the range of 87.9° to 100.5°. 

Nd-Os-Sb. The crystal structure of the NdOs4Sbi2 compound was investigated by Braun and Jeitschko (1980). It was found to adopt the LaFe4Pi2 type structure, a = 0.92989 (X-ray powder diffraction). The purities of the starting materials and the experimental procedures were the same as for LaFe4Sbi2. These results were confirmed by Evers et al. (1995), a = 0.9300 from X-ray single crystal analysis. 

Cycloocta-1,3-diene or cycloocta-1,5-diene react with Re2(CO)l0 to give C8H9Re(CO)3, which has been shown by single-crystal analysis to be a... 

The absolute configuration of the /r -4-dicyanovinylthiochroman derivative 49 has been confirmed as, V at C-3 and R at the adjacent side-chain C atom <2006CC1563> and the (/. (-geometry of the alkene moiety of the heteroarotinoid 50 was established from a single-crystal analysis <2005PS(180)67>. 

Single crystal analysis of 2,6-diphenyl-4-methyloxazolo[5,4-6]pyridine (90) was used to confirm its structure, and the structure of several similarly substituted compounds <92JCS(Pl)70i>. 

Unsymmetrically en -substituted 1,8-diborylnaphthalenes have also been prepared and investigated as bidentate Lewis acids. The synthesis of such derivatives is non-trivial because it necessitates the sequential introduction of boryl moieties at the / en-positions of the naphthalene backbone. Thus far, this strategy has only been applied successfully on few occasions. The reaction of 1,8-dilithionaphthalene-tmeda with one equivalent of dimesitylboronfluoride results in the formation of dimesityl-1,8-naphthalenediylborate 26 as a monoborylated naphthalene product (Scheme ll).32 This derivative is the only example of an anionic 1,8-boron-bridged naphthalene derivative. However, it is important to note that Siebert has reported the synthesis and structure of a neutral 1,8-boron-bridged naphthalene derivative which features a (di-Ao-propylamino)boron moiety bridging the two naphthalene peri-carbon atoms.33 A single-crystal analysis carried out on 26-Li(py)4 confirmed... 

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