Metal complex types

Levelling acid dyes and particularly 1 1 metal-complex types generally require an exceptionally low pH in order to promote exhaustion and levelling up to 3% o.w.f. sulphuric acid is most commonly used for levelling acid dyes, although hydrochloric, formic and phosphoric acids are also effective. In the case of conventional 1 1 metal-complex dyes it is essential to use a sufficient excess of acid over and above the typical 4% o.w.f. sulphuric acid normally absorbed by the wool, otherwise there may be a tendency towards tippy dyeings and lower wet fastness. The actual excess required depends on applied depth and liquor ratio [2] typical recommendations are given in Table 12.2. 

Unsymmetrical monosulphonated dyes of Mr 700-900. The presence of the ionic solubilising group reduces manufacturing costs and minimises the staining of adjacents in severe wet tests, but these dyes are more sensitive to dye-affinity differences than are the unsulphonated 1 2 metal-complex types. 

In their polynuclear metal complexes, Type 7 ligands mainly bind metals through the N—N single bonds in a trans form (mode 4) as shown in (Scheme 30). 

These two recent communications of a high-yielding catalytic asymmetric alkylation of a-imino esters provide access to a variety of non-natural a-amino acids as well as to precursors for natural products, and therefore should prove to be extremely useful. In addition they serve to set expand the palette of metal complex types and catalysis modes for future investigations in this young field. 

We also tested the reactivity and selectivity of mono metalated complexes (Type V). These catalysts, although reactive, were in general less selective than bimetal-ated compounds with head-to-tail configuration. Finally, preliminary studies of reactivity of doubly metalated compounds with the head-to-head configuration (Type Vllb) showed that these compounds are not promising catalysts for C-H insertion reactions. 

Uses Cheiating auxiliary suspending agent helps to disperse sodium silicate yielding softer goods after washing safe for use in dyebath with direct and reactive dyes, incl. metal-complex types... 

Pd-cataly2ed reactions of butadiene are different from those catalyzed by other transition metal complexes. Unlike Ni(0) catalysts, neither the well known cyclodimerization nor cyclotrimerization to form COD or CDT[1,2] takes place with Pd(0) catalysts. Pd(0) complexes catalyze two important reactions of conjugated dienes[3,4]. The first type is linear dimerization. The most characteristic and useful reaction of butadiene catalyzed by Pd(0) is dimerization with incorporation of nucleophiles. The bis-rr-allylpalladium complex 3 is believed to be an intermediate of 1,3,7-octatriene (7j and telomers 5 and 6[5,6]. The complex 3 is the resonance form of 2,5-divinylpalladacyclopentane (1) and pallada-3,7-cyclononadiene (2) formed by the oxidative cyclization of butadiene. The second reaction characteristic of Pd is the co-cyclization of butadiene with C = 0 bonds of aldehydes[7-9] and CO jlO] and C = N bonds of Schiff bases[ll] and isocyanate[12] to form the six-membered heterocyclic compounds 9 with two vinyl groups. The cyclization is explained by the insertion of these unsaturated bonds into the complex 1 to generate 8 and its reductive elimination to give 9. 

Section 14 14 Transition metal complexes that contain one or more organic ligands offer a rich variety of structural types and reactivity Organic ligands can be bonded to a metal by a ct bond or through its it system Metallocenes are transition metal complexes m which one or more of the ligands is a cyclopentadienyl ring Ferrocene was the first metallocene synthesized Its electrostatic potential map opens this chapter... 

In Section 8, the material on solubility constants has been doubled to 550 entries. Sections on proton transfer reactions, including some at various temperatures, formation constants of metal complexes with organic and inorganic ligands, buffer solutions of all types, reference electrodes, indicators, and electrode potentials are retained with some revisions. The material on conductances has been revised and expanded, particularly in the table on limiting equivalent ionic conductances. 

Mostly, positive-ion FAB yields protonated quasi-molecular ions [M -i- H]+, and the negative-ion mode yields [M - H]. In the presence of metal salts (e.g., KCl) that are sometimes added to improve efficiency in the LC column, ions of the type [M -i- X]+are common, where X is the metal. Another type of ion that is observed is the so-called cluster, a complex of several molecules with one proton, [M -i- H]+ with n = 1, 2, 3,. .., etc. Few fragment ions are produced. 

Polyatomic molecules cover such a wide range of different types that it is not possible here to discuss the MOs and electron configurations of more than a very few. The molecules that we shall discuss are those of the general type AFI2, where A is a first-row element, formaldehyde (FI2CO), benzene and some regular octahedral transition metal complexes. 

In contrast to metal complexes of OjoTydroxyazo types, these terminally metallized dyes derived from the o-hydroxy carboxyl stmctures undergo httie color change on metallization and exhibit Httie improvement ia lightfastness (49). 

Another class of metal complex dyes is derived from the formazan stmcture. These dyes are appHed to wool and nylon from a neutral or weakly acidic dyebath analogous to the 2 1 premetallized OjO -dihydroxyazo complexes. The bluish-gray dye Cl Acid Black 180 [11103-91-6] (61) (Cl 13710) is a 2 1 cobalt complex of the formazan type. 

The second type is comprised of 2 1 metal complexes of OjO -dihydroxy azo dyes which generally do not contain sulfo or other strongly hydrated groups as found ia the premetallized 2 1 complexes for wool. Thus their solubiUty ia esters, ketones, and alcohols is relatively iacreased. Cl Solvent Violet 1... 

Carbon monoxide [630-08-0] (qv), CO, the most important 7T-acceptor ligand, forms a host of neutral, anionic, and cationic transition-metal complexes. There is at least one known type of carbonyl derivative for every transition metal, as well as evidence supporting the existence of the carbonyls of some lanthanides (qv) and actinides (1) (see AcTINIDES AND THANSACTINIDES COORDINATION COMPOUNDS). 

Technetium-99m coordination compounds are used very widely as noniavasive imaging tools (35) (see Imaging technology Radioactive tracers). Different coordination species concentrate ia different organs. Several of the [Tc O(chelate)2] types have been used. In fact, the large majority of nuclear medicine scans ia the United States are of technetium-99m complexes. Moreover, chiral transition-metal complexes have been used to probe nucleic acid stmcture (see Nucleic acids). For example, the two chiral isomers of tris(1,10-phenanthroline)mthenium (IT) [24162-09-2] (14) iateract differentiy with DNA. These compounds are enantioselective and provide an addition tool for DNA stmctural iaterpretation (36). 

In contrast, chromium (ITT) and cobalt(III) form 2 1 dye metal complexes that have nonplanar stmctures. Geometrical isomerism exists. The (9,(9 -dihydroxyazo dyes (22) form the Drew-Pfitzner or y rtype (23) (A = C = O) whereas o-hydroxy—o -carboxyazo dyes (24) form the Pfeiffer-Schetty or fac type (25), where A = CO 2 and C = O. 

The solvated sulfenamides [Li2( BuNSC6H4Me-4)2(THF)n] (n = 2,4) have dimeric structures with a central Li2N2 ring. The coordination mode is determined by the extent of solvation of the Li" ions monosolvation allows for rj -N,S coordination whereas disolvation restricts the coordination mode to // -M Variable temperature NMR studies indicated that a dynamic exchange between these two structural types occurs in THF solution (Scheme 10.10). The dihapto coordination mode is observed exclusively in transition-metal complexes and the... 

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