X-ray crystallography complex

Reactions of c -[Ru(bpy)2Cl2] with ligands (86) or (87) (X = CH2) in EtOH(aq) lead to [Ru(bpy)2(86)] + and [Ru(bpy)2(87, X = CH2)] respectively. When X = 0 in ligand (87), the product is the pyridine carboxylate complex [Ru(bpy)2(pyC02)], the structure of which is confirmed by X-ray crystallography. Complexes of the type [Ru(bpy)2L] " in which L represents a series of mono- and dihydrazones have been prepared and characterized by spectroscopic methods (including variable temperature H NMR) and a structure determination for L = biacetyl di(phenylhydrazone). When L is 2-acetylpyridine hydrazone or 2-acetylpyridine phenylhydrazone, [Ru(bpy)2L] + shows an emission, but none is observed for the dihydrazone complexes. The pyrazoline complex [Ru(bpy)2L] (L = 5-(4-nitrophenyl)-l-phenyl-3-(2-pyridyl)-2-pyrazoline) can be isolated in two diastereoisomeric forms. At 298 K, these exhibit similar MLCT absorptions, but at 77 K, their emission maxima and lifetimes are significantly different. ... 

Studies have been made of the photochemical reactions of vinyloxiranes with iron carbonyl. The four diastereoisomers of 2,4-hexadienemonooxirane take part in photochemical reactions that are stereospecific. The structure of the iron complex has been determined by x-ray crystallography. Complexes formed from dienemonooxiranes with iron carbonyl can be oxidized to lactones. ... 

The reaction of 1,2,3-triphenylcyclopropenylium ion 28 with sodium dicarbonyl(// -cyclopen-tadienyl)ferrate afforded the tr-complex, dicarbonyl(f -cyclopentadienyl)(l,2,3-triphenylcy-cloprop-2-enyl)iron (29), whose structure was determined by X-ray crystallography." Complex 29 was transformed into the original cyclopropenylium ion or its dimer by various reagents."... 

The conformation of derivatives of bicyclo[3.3.1]nonane has been the subject of many studies, based on proton nuclear magnetic resonance ( H-NMR), C-NMR, infrared (IR) and Raman spectroscopy, dipole measurements, X-ray crystallography, complexation experiments and various types of computational studies. Most of this work has been reviewed in detail (26,118, 119), and here we only report a summary of the general aspects. 

The tantalum(IV) hydrides [TaH2Cl2(PMe3)4] (51) and [TaH2Cl2(dmpe)2] (50) were characterized by low temperature X-ray crystallography. Complex (51) adopts a distorted dodecahedral geometry in the solid state, wlule (50) is better described as a distorted square antiprismatic complex. The hydrogen atoms have been located. 

From this point of view the understanding of methylidene decomposition and stability is important for designing a more stable catalytic system. Usually, the catalyst destruction was studied based only on kinetic experiments without isolation and identification of products of decomposition [8,10,11]. Recently, Grubbs and coworkers isolated the major product formed after heating of (6a) in benzene solution (Eq. 2) [9]. The structure of (7) was proved by x-ray crystallography. Complex (7) was isolated with yield 46%. It has been shown that this complex is responsible for the C=C double bond isomerization [9]. 

R = H), and coniine (12) were isolated (16) (Table 1). But, because the science was young and the materials complex, it was not until 1870 that the stmcture of the relatively simple base coniine (12) was estabUshed (17) and not until 1886 that the racemic material was synthesized (18). The correct stmcture for strychnine (13, R = H) was not confirmed by x-ray crystallography until 1956 (19) and the synthesis was completed in 1963 (20). 

The maridomycin complex of seven factors (40), Type II in Table 5, was obtained from culture broths of S. hjgwscopims (182—188). The principal difference from the leucomycins is a 12,13-epoxide. Confirmation of stmcture was obtained from x-ray crystallography and spectroscopy of 9-0-acyl derivatives of maridomycin III (188,189). 

The stmcture of the blue material was not elucidated until 1934, when it was shown to be the iron complex of (67). The new material was christened phthalocyanine [574-93-6] reflecting both its origin from phthaUc anhydride and its beautihil blue color (like cyanine dyes). A year later the stmcture was confirmed by one of the first uses of x-ray crystallography. 

These interesting results have been quoted by Sokolov (79RCR289) and by Acheson and Elmore (78AHC(23)263). However, they proved to be erroneous, as to both structure (348) (a fluoroborate, not a complex) and structure (349) (for which (350) represents the correct structure established by X-ray crystallography (83T2193)). 

X-ray crystallography, 3, 623 Ruscodibenzofuran synthesis, 4, 698, 709 Ruthenacyclobutane, 3-cyano-synthesis, 1, 667 Ruthenium complexes with pyridines, 2, 124 triazenido, 5, 675 Rutin... 

Bahar et al. [46] have used this kind of approach to predict the B-factors of 12 X-ray structures. Elements in the Hessian corresponding to atom pairs separated by a distance of less than 7 A are set to zero, and the remainder have the same value dependent on a single adjustable parameter. Generally B-factor predictions for the a-carbons compare very well with the B-factors measured by X-ray crystallography. Figure 1 shows the result for the subunit A of endodeoxyribonuclease I complexed with actin. 

In the two complexes studied by x-ray crystallography, the interactions between TBP and the DNA, as well as the deformation of the B-DNA structure, are very similar, and we will illustrate some of these details for the yeast structure. Minor details of the two complexes vary due to differences in some of the side chains and nucleotides that are present in the interaction areas. 

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