Single crystal X-ray structural analysis

From single-crystal X-ray structural analysis the ground-state conformation of (.S )-2-(4-meth-ylphenylsulfinyl)-2-cyclopentenone was shown to have the sulfoxide bond orientated anti to the carbonyl bond, as expected for minimization of electrostatic interactions13. 

We also performed a single-crystal X-ray structure analysis of this lead compound. The solid state structure of this compound depicted in Fig. 3-15 shows a half-boat-like ( sofa ) conformation with the 9-phenanthryl group in a quasi-axial or r/Mf/.v/-flagpole position, and the a, 3-unsaturated exocyclic ester in a s-cis conformation. This cleft-like conformation is advantageous for the creation of centers with a high recognition ability, since one enantiomer fits in better than the other thus leading to selectivity. 

The specific features of the cluster compounds of technetium are such, that practically each new compound must be studied using single crystal X-ray structural analysis, because their complex structures do not allow the interpretation of the results from other physico-chemical methods of investigation. Therefore, the synthesis of single crystals suitable for X-ray structural analysis is the main and most laborious chemical task. 

A single crystal X-ray structure analysis of 8 (Fig. 4) confirms the molecular constitution of the compound deduced by spectroscopic methods and shows further structural details. The molecule is dimeric with a Mn-C15 ( -carbyne) bond length of 1.857(2) A and a Mn-Mn bond distance of 2.565(1) A the latter one is typical for a Mn-Mn single bond [13]. The Mn-C15 (carbyne) bond is short compared to known Mn-C single bonds, for example that in (OC)4Mn-C(C00Et)C(HgBr)C(0Et)0 is found to be 2.051(26) A [13b], For the acyclic carbyne complex [Cp(CO)2Mn = C-CH=CPh2]+ BF4 the MnC distance is 1.665(5) A [14] comparable values for... 

Reaction of the carbonyl complex 26 with the mercury diazomethane 27 gives the highly reactive 17e intermediate carbyne complex 28 which dimerizes to form the / -biscarbyne complex 30. In this case, the intermediate terminal carbyne complex 28 has been trapped by reaction with the mercury diazomethane 29 to form the cyclic vinylidene complex 31. 31 was also characterized by a single crystal X-ray structure analysis. 

Bekiaris et al. have studied the reaction of fluorinated pentane-2,4-diones and phosphanes and have reported the formation of bicyclic compounds and phosphaadamantanes <1997CB1547>. Compounds 167 and 168 were formed in a diasteroselective manner (Scheme 13) and their structures were determined by single crystal X-ray structure analysis. 

The cluster anion, [Os3Ir(CO)i3], was prepared in 50% yield by reaction of Os3(CO)i2 with [Ir(CO)4]. The single-crystal X-ray structure analysis shows it to consist of a tetrahedral metal core with one of the 13 carbonyl ligands bridging. The catalytic activity for carbonylation of... 

Similarly, the (—)-menthyl substituted stannyl bromides 51 and 53, whose diastereomeric purity was confirmed by single crystal X-ray structure analysis, were found to slowly equilibrate to nearly 1 1 mixtures of diastereoisomers on standing in solution (equation 13)28. 

Recently, the successful generation of PCU-8-vinylidenecarbene (4a) via reaction of 8-(dibromo-methylene)-PCU (3) with n-BuLi hs been reported [15]. When this reaction is performed in the presence of an alkene trapping agent (i.e., cyclohexene), a cage-functionalized erro-methylenecyclopropane, 5, is the only product. Compound 5 subsequently was characterized via conversion to the corresponding substituted dichlorospiro(cyclopentane), 6 (Scheme 2) the structure was established unequivocally via single-crystal X-ray structural analysis [15]. 

The reaction of 4-(dibromomethylene)pentacyclo[6.3.0.0 .0 °.0 ]undecane (11) with n-BuLi resulted in the corresponding vinylidenecarbene, 12a, which could be trapped in situ by cyclohexene to obtain the corresponding cage-functionalized exo-methylenecyclopropane (i.e., 13, Scheme 4). Compound 13 subsequently was characterized via conversion into 14 (Scheme 4), which structure was established unequivocally via single-crystal X-ray structural analysis [18]. 

The corresponding cycloadduct, 21, which structure was established unequivocally via single-crystal X-ray structural analysis [22], was obtained by trapping 20 in situ by cyclohexene. 

The best method used in the conformational analysis of saturated six-membered heterocyclic rings in the solid state is single-crystal X-ray structural analysis. The conformation in solution is not always identical. For solutions, H NMR spectroscopic analysis has been employed widely in the field of conformational analysis. The following methods deserve special mention. 

The nature of the anomeric effect in the bicyclic /ra r-fused octahydro-l-methyl-l//-2,l-benzothiazine 2,2-dioxide 37 has been examined by single crystal X-ray structure analysis (Figure 5) <1998CJC164>. The crystal structure of 37 shows that the A -Me group assumes an axial position in the solid state. The authors suggest that this conformation is also the most stable in solution and propose that this hyperconjugation effect is >2.0 kcal mol . ... 

In this section the methods which have been used to gain structural information are briefly summarized. The term structure is used in this context in its broadest sense, including more qualitative observations concerning the skeleton of the bridging atoms. As a general rule, the hydroxo-bridged polynuclear complexes of chromium(III) and cobalt(III) can be isolated as well-defined crystalline salts and it is therefore quite natural that single-crystal X-ray structure analysis has... 

The incorporation of an amide bond in the substrate provided l,4-diazepin-2-ones as single diastereomers with the stereochemistry at C-5 determined by single crystal X-ray structure analysis, as depicted in Scheme 46 <2006OL3425>. 

Single crystal X-ray structural analysis was carried out for 4,7-bis(l,3-dithian-2-ylidene)-l,2,3,5,6-pentathiepane (see Section 13.17.7.13) <1995MI1>. 

Therefore, single-crystal X-ray structural analysis has hitherto been of limited use for structure elucidation of dendrimers. Most of the examples found in the literature [42 a] are actually single-crystal X-ray structural analyses of rigid, dimensionally stable (shape resistent) polyphenylene dendrimers [42 b] or of me-tallodendrimers [43] or polysilane dendrimers. 

A single-crystal X-ray structure analysis revealed that the intensely brown colored Pbio2- anion has a bicapped square-antiprismatic structure of nearly perfect Dm symmetry. 

The single crystal X-ray structure analysis of the trimethyltin-substituted ammonium salt [H2N(SnMe3)2][SnMe3Cl2] (115)247 was also reported. In compound 115 the anion... 

The solid is stable toward sunlight and moist air. A single-crystal X-ray structural analysis showed the P —Te —P group to be linear with P — Te bond lengths of 238.8 and 341.2 pm4. Mixtures of tri-/-butylphosphane telluride/tri-/-butylphosphane or tris[dimethylamino] phosphane telluride/tris[dimethylamino]phosphane in toluene were observed by NMR spectroscopic methods to form compounds with a P-Te-P group5. 

A single-crystal X-ray structural analysis of bis[ethylenethiourea]tellurium dithiocyanate showed the tellurium atom to be coordinated to four sulfur atoms with planar trans-arrangement of the ligands1. 

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