Stereochemistry tris complexes

The dicyano complexes [Fe(bipy)2(CN)2]X and [Fe(phen)2(CN)2]X (X = C104, N03) are also low-spin with magnetic properties63 and Mossbauer spectra59 (Table 1) comparable with those of the tris complexes. Little or no tlg electron delocalization was apparent in the magnetic results. The stereochemistry of these mixed ligand complexes is presumably cis. 

Chiu Fan Liu, Nora C. Liu and J. C. Bailar, Jr., The Stereochemistry of Complex Inorganic Compounds. XXVII. Asymmetric Syntheses of Tris-Bipyridine Complexes of Ruthenium-(II) and Osmium(III), Inorg. Chem. 3 1197 (1964). 

Europium, tris(2,2,6,6-tetramethyl-3,5-heptanedione-quinuclidine)-stereochemistry, 1, 81 Europium complexes... 

Lead, tris(ethyldithiocarbonato)-stereochemistry. 1,82 structure, 1, 82 Lead bromide, 3.194 Lead bromide hydrate, 3, 195 Lead carboxylatcs, 3,222 Lead complexes, 3,183-223 r 6-arene, 3,220 bivalent... 

Niobium, tris(diethyldilhiocarbamato)oxy-stereochemistry, 1,82 structure, 1, 83 Niobium, tris(oxa ato)oxy-stereochcmistry, 1, 82 Niobium, tris(phcnylcncdirhio)-structure, 1, 63 Niobium alanate, 3, 685 Niobium complexes alkyl alkoxy reactions, 2, 358 amides, 2,164 properties, 2, 168 synthesis, 2, 165 applications, 6,1014 carbamicacid, 2, 450 clusters, 3, 672,673,675 hexamethylbenzene ligands, 3, 669 cyanides synthesis, 2, 9 p-dinitrogen, 3, 418 fluoro... 

Tellurium, tris(diethyldithiocarbamato)phenyl-stereochemistry, 1, 82 Tellurium complexes acetylacetone, 2, 370 heterocyclic... 

Tin, nitratodiphenyltris(dimethy) sulfoxide)-structure, 1,77 Tin, nitratotris(triphenyltin)-structure, 1, 47 Tin,tetrakis(acetato)-stereochemistry, 1,94 Tin, tetrakis(diethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetrakis(ethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetranitrato-stereochemistry, 1, 94 Tin, tri-n-butylmethoxy-, 3, 208 Tin alkoxides physical properties, 2, 346 Tin bromide, 3, 194 Tin bromide hydrate, 3,195 Tin carboxylates, 3, 222 mixed valence, 3, 222 Tin chloride, 3, 194 hydroformylation platinum complexes, 6, 263 Tin chloride dihydrate, 3,195 Tin complexes, 3, 183-223 acetyl ace tone... 

Titanium, tetrakis(trimethysilyl)oxy-, 3, 334 Titanium, tetranitrato-stereochemistry, 1,94 Titanium, triaquabis(oxalato)-structure, I, 78 Titanium, tris(acetylacetone)-structurc, 1,65 Titanium alkoxides oligomeric structure, 2,346 synthesis ammonia, 2, 338 Titanium chloride photographic developer, 6,99 Titanium complexes acetylacetone dinuclear, 2, 372 alkyl... 

Ytterbium, trinitratotris(dimethyl sulfoxide)-structure, 1, 97 Ytterbium, tris(acetylacetone)(4-ammo-3-penten-stereochemistry, 1,81 Ytterbium complexes acetylacetone, 2,373 dipositive oxidation state hydrated ions, 3,1109 polypyrazolylborates, 2,255 Ytterbium(III) complexes ethyl glycinate, diacetate... 

Heterocyclic nitrogen donors and their adducts with zinc chloride have been studied.623,624 A large number of other ligand systems have also been characterized, for example, zinc halide adducts of 2,2-dimethylpropane-1,3-diamine and hexamethylphosphoramide have been studied.625,626 The formation of mixed ligand complexes with chloride and substituted pyridines has been studied.627 The zinc tris(pyridyl) chloride anion has also been structurally characterized.628 Manganese(II) ions have been used to probe the stereochemistry in reactions of zinc halides with pyrazine.629... 

An easily accessible hexadentate derivative of tacn, namely 1,4, 7-tris(u-aminobenzyl)- 1,4,7-triazacyclononane (tabtacn), forms a 1 1 complex [Cd(tabtacn)](C104)2 0.5 H20 Pc2 njPna2, Z = 4) with a distorted trigonal prismatic CdN6 core. The Cd—N bonds to the N donors in both the tacn moiety and in the aniline pendant arms are very similar in a rather narrow range (rav(Cd—N) 237 pm).178 Both solution and solid-state H, 13C, and 113Cd NMR spectra have been measured and analyzed with respect to details of the stereochemistry and to dynamics in solution. 

We hope that this review of chiral sulfur compounds will be useful to chemists interested in various aspects of chemistry and stereochemistry. The facts and problems discussed provide numerous possibilities for the study of additional stereochemical phenomena at sulfur. As a consequence of the extent of recent research on the application of oiganosulfur compounds in synthesis, further developments in the field of sulfur stereochemistry and especially in the area of asymmetric synthesis may be expected. Looking to the future, it may be said that the static and dynamic stereochemistry of tetra- and pentacoordinate trigonal-bipyramidal sulfur compounds will be and should be the subject of further studies. Similarly, more investigations will be needed to clarify the complex nature of nucleophilic substitution at tri- and tetracoordinate sulfur. Finally, we note that this chapter was intended to be illustrative, not exhaustive therefore, we apologize to the authors whose important work could not be included. 

We have discussed in this chapter the thermal pyrolyses of a number of strained ring compounds. In most of the cases considered there is good evidence that the processes are unimolecular. Where possible we have tried to suggest plausible transition complexes, and reaction paths, based on a consideration of such factors as the kinetic parameters, stereochemistry of the reaction and effect of substituents. In reactions of this type, the description of the transition complex is fraught with difficulties, since the absence of such things as solvent effects (which can be so helpfrd in bimolecular reactions) limit the criteria on which such descriptions may be based. Often two types of transition complex may be equally good at accounting for the observed data. Sometimes one complex will explain some of the data while another is better able to account for the remainder. It is probable that in many cases our representation... 

Since the early times of stereochemistry, the phenomena related to chirality ( dis-symetrie moleculaire, as originally stated by Pasteur) have been treated or referred to as enantiomericaUy pure compounds. For a long time the measurement of specific rotations has been the only tool to evaluate the enantiomer distribution of an enantioimpure sample hence the expressions optical purity and optical antipodes. The usefulness of chiral assistance (natural products, circularly polarized light, etc.) for the preparation of optically active compounds, by either resolution or asymmetric synthesis, has been recognized by Pasteur, Le Bel, and van t Hoff. The first chiral auxiliaries selected for asymmetric synthesis were alkaloids such as quinine or some terpenes. Natural products with several asymmetric centers are usually enantiopure or close to 100% ee. With the necessity to devise new routes to enantiopure compounds, many simple or complex auxiliaries have been prepared from natural products or from resolved materials. Often the authors tried to get the highest enantiomeric excess values possible for the chiral auxiliaries before using them for asymmetric reactions. When a chiral reagent or catalyst could not be prepared enantiomericaUy pure, the enantiomeric excess (ee) of the product was assumed to be a minimum value or was corrected by the ee of the chiral auxiliary. The experimental data measured by polarimetry or spectroscopic methods are conveniently expressed by enantiomeric excess and enantiomeric... 

The very useful lanthanide shift reagents, which facilitate analysis of molecular stereochemistry because of their line-broadening characteristics in NMR spectra, were studied when bound as a chelate complex to thietanes. X-Ray analysis of the adduct 3,3-dimethylthietane 1-oxide with tris(dipivalo-methanato)europium(III) [Eu(dpm)3] revealed the structure of a seven-coordinate complex (271). ... 

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