Titanium Transition metal ions

Magnesium reacts slowly at lower temperatures to give the amide, as do all active metals this reaction is catalyzed by transition metal ions. Aluminum nitride [24304-00-5] AIN, barium nitride [12047-79-9] Ba2N2, calcium nitride [12013-82-0] Ca2N2, strontium nitride [12033-82-8], Sr2N2, and titanium nitride [25583-20-4], TiN, may be formed by heating the corresponding amides. 

Li3(BN2) have already demonstrated the decomposition of (BN2) ions into boron nitride. The remaining nitride can lead to the formation of a binary metal nitride or reduce the transition metal ion under the formation of N2. Both mechanisms have been obtained experimentally, depending on the stability of the metal nitride. For instance niobium pentachloride forms NbN, titanium trichloride forms TiN, and nickel dichloride forms Ni, plus BN and nitrogen, respectively, in reactions with Li3(BN)2 (at 300-600°C) [24]. 

Organic hydroperoxides have also been used for the oxidation of sulphoxides to sulphones. The reaction in neutral solution occurs at a reasonable rate in the presence of transition metal ion catalysts such as vanadium, molybdenum and titanium - , but does not occur in aqueous media . The usual reaction conditions involve dissolution of the sulphoxide in alcohols, ethers or benzene followed by dropwise addition of the hydroperoxide at temperatures of 50-80 °C. By this method dimethyl sulphoxide and methyl phenyl sulphoxide have been oxidized to the corresponding sulphone in greater than 90% yields . A similar method for the oxidation of sulphoxides has been patented . Unsaturated sulphoxides are oxidized to the sulphone without affecting the carbon-carbon double bonds. A further patent has also been obtained for the reaction of dimethyl sulphoxide with an organic hydroperoxide as shown in equation (19). 

Hi. Zeolites exchanged with transition metal ions. In the first row, scandium-, titanium-, cobalt-, and nickel-exchanged zeolites have been the most studied. Cobalt-exchanged zeolites are discussed in Section IV,E since they lead to oxygen adducts on adsorption of oxygen. There are several cases where copper and particularly iron ions are found as impurity cations which affect the oxygen adsorption properties of the zeolite. 

Ti ion-implanted titanium oxides exhibited no shift, showing that such a shift is not caused by the high energy implantation process itself, but to some interaction of the transition metal ions with the titanium oxide catalyst. As can be seen in Fig. 10-1 ((b)—(d)), the absorption band of the Cr ion-implanted titanium oxide shifts smoothly to visible light regions, the extent of the red shift depending on the amount and type of metal ions implanted, with the absorption maximum and... 

Change in the selectivity patterns of transition metal ion/H+ systems has been encountered with the amorphous and anatase types of hydrous titanium oxides with different crystallinities [24]. Potassium titanate, KjO nXi02 (n = 2-4), in particular, exhibits a layered structure. Fibrous titanic acid, H2Ti409 nHjO, is obtained by acid treatment of fibrous K2Ti409 nH20 and shows higher selectivity for K, Rb and Cs than the amorphous titanic acid [206]. 

Transition metal ions, in particular, titanium (IV) and iron (III)... 

Anhydrous AI2O3 occurs naturally as the extremely hard, high-melting mineral corundum, which has a network structure. It is colorless when pure, but becomes colored when transition metal ions replace a few Al + ions in the crystal. Sapphire is usually blue and contains some iron and titanium. Ruby is red due to the presence of small amounts of chromium. 

The third principal application of the electron spin resonance technique is to the study of paramagnetic transition metal ions in biochemical systems. Most examples are complexes of copper, iron, manganese, chromium, cobalt and molybdenum. Other metals such as titanium, vanadium and nickel are sometimes employed as structural probes. Only four of these ions, Cu ", Mn, Gd " and VO ", are seen in ESR spectroscopy at room temperature under virtually all conditions. Therefore, they are of special importance. 

In anaerobic soils, the individual chemistry of the ions is more distinctive. The transition metal ions in the middle of each period of the periodic table—chromium, manganese, iron, nickel, cobalt, and copper—can reduce to lower oxidation states, while the end members—scandium, titanium, and zinc—have only one oxidation state. The lower oxidation states are more water soluble but still tend to precipitate as carbonates and sulfides, or associate with organic matter, thus reducing their movement but increasing then plant availability. 

Electron Configurations of Transition Metal Ions In contrast to most main-group ions, transition metal ions rarely attain a noble gas configuration, and the reason, once again, is that energy costs are too high. The exceptions in Period 4 are scandium, which forms Sc ", and titanium, which occasionally forms Ti in some compounds. The typical behavior of a transition element is io form more than one cation by losing all of its ns and some of its (n — l)d electrons. (We focus here on the Period 4 series, but these points hold for Periods 5 and 6 also.)... 

A novel means of enzyme insolubilization involves chelation. " " Treatment of cellulose with titanium or other transition-metal ion activates the polysaccharide, which then reacts directly with enzymes. Presumably, in the activation, one of the water molecules in the octahedral, hexahydrated titanium (IV) ion becomes replaced by a polysaccharide hydroxyl group, and, in the second stage, another water molecule is displaced by an amino, carboxyl, or hydroxyl group of the enzyme. 

Acid catalysts, transition metal redox catalysts, and titanium zeolites are all known to be effective for phenol hydroxylation. Acid catalysis proceeds by an ionic mechanism involving an intermediate hydroxonium ion (H3O2+) whereas some transition metal ions promote the formation of hydroxyl radicals to effect substitution. However the introduction of a second hydroxyl substituent onto the aromatic nucleus tends to activate the molecule towards further reaction and this leads to the formation of unwanted, tarry by-products. The commercial solution is to use very low mole ratios of hydrogen peroxide to phenol and to recycle the unreacted phenol, ie. operate at low conversion. Some typical commercial methods are given in Table 1. 

---