Chromium complexes Group 8 metals

Mordant dyes have hydroxy groups in their molecular stmcture that are capable of forming complexes with metals. Although a variety of metals such as iron, copper, aluminum, and cobalt have been used, chromium is most preferable as a mordant. Alizarin or Cl Mordant Red 11 [72 8-0] (1) (Cl 58000), the principal component of the natural dye obtained from madder root, is the most typical mordant dye (see Dyes, natural). The aluminum mordant of alizarin is a well-known dye by the name of Turkey Red and was used to dye cotton and wool with excellent fastness. However, as is the case with many other mordant dyes, it gave way to the vat or the azoic dyes, which are applied by much simpler dyeing procedures. 

The reaction is catalyzed by a group VIII metal species, particularly that of rhodium or palladium. The initial metal species may be any variety of complexes (e.g., PdCl2 Pd acetate, etc.). A source of halide is necessary iodide is especially effective. The most convenient source is methyl iodide, since it is likely a reaction intermediate. In addition, an organic promoter must be included for catalytic activity. These promoters are generally tertiary phosphines or amines. Also, chromium complexes were found to have an important promotional effect. 

The supported chromium complex "CHRISS" was first reported by us in 1997 (Figure 6) [10]. It was shown to be stable to reaction conditions and an active catalyst for the oxidation of methylaromatics with air as the only consumable source of oxygen. The catalyst was prepared by first forming in solution a metal complex with pendant triethoxysilane groups which is then imprinted onto a silica gel surface. 

Interaction of metals with cyclopropenylidene to form stable complexes has been widely studied340 in the last two decades since the first reported synthesis of pentacarbonyl(2,3-diphenylcyclopropenylidene)chromium (see belowy4. Two groups of cyclopropenylidene metal derivatives may be distinguished neutral cyclopropenylidene complexes represented by two resonance forms, and the cationic cyclopropenylium transition metal complexes of groups 6 (Cr, Mo, W), 7 (Mn), 8 (Fe) and 10 (Pd, Pt), whereas the latter cationic cr-complexes are derived from both main group metals (Li, Mg) and group 10 (Pd, Pt) transition metals. 

In afterchroming the dye is allowed to go onto the fiber from an acid bath, and this is followed by treatment with dissolved alkali metal dichromate, which is reduced by the cystine group of the wool to trivalent chromium compounds. The chromium complex formed on the wool fiber contains two azo dye radicals for each metal atom (1 2 complex). 

Chromium Complexes Containing Sulfonic Acid Groups. The production of premetallized complex dyes began in 1912, when R. Bohn of BASF synthesized 1 1 chromium complexes and BA SF and CIBA introduced ranges of sulfonic acid containing 1 1 chromium complex azo dyes. No metal other than chromium is suitable for this class of dyes. 

Metal Complexes with Hydrophilic Groups. In 1949 the water soluble 1 2-chromium complex 10 [12218-94-9] was introduced [13],... 

Chromium Complexes with One Sulfonic Acid Group. By definition, l 2-metal complexes with one sulfonic acid group must be unsymmetrical, because only one of the two azo dye ligands bears a sulfonic acid group. In 1962 the first metal-... 

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