Orange cationics

When the solution is wanned to room temperature, the orange cation radical... 

Whereas in acetonitrile the rate limiting step is an opening of the solvent shell of a reactant, in benzonitrile the back reaction of (5) between the protonated acridine orange cation (BH ) and the 3-methyl-4-nitrophenolate ion (A ) to form the ion pair is diffusion controlled (although the overall reaction to the neutral molecules is an endothermic process). Because of its lower dielectric constant than acetonitrile, the electrostatic interactions between reactants in benzonitrile outweigh specific solvent effects. In other words, in benzonitrile a rate limiting coupling of proton transfer to the reorientation of solvent dipoles does not occur and the measured rates are very fast. The ion recombination (I) + (II) in benzonitrile has a diffusion controlled specific rate (theoretical) k = 9 -1 -1... 

For the N-alkylated acridine orange cation on colloidally dispersed mont-morillonite (199) and zirconium phosphate (200) in aqueous systems, the orienta-... 

The binding of acridine orange to heparin is stabilized by dye-dye and dye-polymer interactions and by entropic factors. The predominant interaction appears to be electrostatic, between the acridine orange cation and the heparin polyanion. 

Lead ll) oxide, PbO, exists in two forms as orange-red litharge and yellow massicot. Made by oxidation of Pb followed by rapid cooling (to avoid formation of Pb304). Used in accumulators and also in ceramics, pigments and insecticides. A normal hydroxide is not known but hydrolysis of lead(II) oxyacid salts gives polymeric cationic species, e.g. [Pb OfOH) ] and plumbates are formed with excess base. 

If triphenylmethyl chloride in ether is treated with sodium, a yellow colour is produced due to the presence of the anionic spiecies PhsC". Alternatively, if triphenylmethyl chloride is treated with silver perchlorate in a solvent such as THF, the triphenylmethyl cation is obtained. More conveniently, triphenylmethyl salts, PhsC X", can be obtained as orange-red crystalline solids from the action of the appropriate strong acid on triphenylcarbinol in ethanoic or propanoic anhydride solution. The perchlorate, fluoroborate and hexafluoro-phosphate salts are most commonly used for hydride ion abstraction from organic compounds (e.g. cycloheptatriene gives tropylium salts). The salts are rather easily hydrolysed to triphenylcarbinol. 

Calcium, strontium and barium produce characteristic flame colours like the Group 1 cations (calcium, orange strontium, red barium, green) and flame photometry can be used for their estimation. All give insoluble carbonates in neutral solution. 

Plutonium(III) in aqueous solution, Pu " ( 4)> is pale blue. Aqueous plutonium(IV) is tan or brown the nitrate complex is green. Pu(V) is pale red-violet or pink in aqueous solution and is beUeved to be the ion PuO Pu(VI) is tan or orange in acid solution, and exists as the ion PuO. In neutral or basic solution Pu(VI) is yellow cationic and anionic hydrolysis complexes form. Pu(VII) has been described as blue-black. Its stmcture is unknown but may be the same as the six-coordinate NpO (OH) (91). Aqueous solutions of each oxidation state can be prepared by chemical oxidants or reductants... 

Basic Orange 1 (130) (aniline coupled to 2,4-diamiaotoluene) and Basic Orange 2 (22) (aniline coupled to y -phenylenediamiae) are examples of amine salt type cationic azo dyes. The cation is formed by protonation under acidic conditions. Under neutral or alkaline conditions, these dyes behave more like disperse dyes. In 1988 the U.S. production of Cl Basic Orange 2 amounted to 132 tons. 

The dichromate(VI) salts may be obtained by the addition of acid to the chromate(VI) salts. However, they are better prepared by adding one-half the acid equivalent of a metal hydrate, oxide, or carbonate to an aqueous solution of CrO, then removing the water and/or CO2. Most dichromates(VI) are water-soluble, and the salts contain water(s) of hydration. However, the normal salts of K, Cs, and Rb are anhydrous. Dichromate(VI) compounds of the colorless cations are generally orange-red. The geometry of Ci2 is described as two tetrahedral CrO linked by the shared odd oxygen (72). 

The first X-ray crystal structure of a species containing an S-I bond was of the curious and unexpected cation [87 ]+ which was found in the dark-orange compound [S7l)+[SbF6] formed when iodine and sulfur react in SbF5 solution.The structure of the cation is shown in Fig. 15.22a and features an 87 ring with alternating 8-8 distances and a pendant iodine atom the conformation of the ring is the same as in 87, 8g, and 8sO (p. 696). The same cation was... 

The yield is almost quantitative and the orange-yellow Cr cation can be reduced to the neutral species with aqueous dithionite ... 

LCo(H20)6] ion, and bidentate /V-donor ligands such as cn, bipy and phen form octahedral cationic complexes [Co(L-L)3] , which are much more stable to oxidation than is the hexaammine [Co(NH3)6l . Acac yields the orange [Co(acac)2(H20)2] which has the tram octahedral structure and can be dehydrated to [Co(acac)2l which attains octahedral coordination by forming the tetrameric species shown in Fig. 26.3. This is comparable with the trimeric [Ni(acac>2]3 (p. 1157), like which it shows evidence of weak ferromagnetic interactions at very low temperatures. fCo(edta)(H20)] is ostensibly analogous to the 7-coordinate Mn and complexes with the same stoichiometry, but in fact the cobalt is only 6-coordinate, 1 of the oxygen atoms of the cdta being too far away from the cobalt (272 compared to 223 pm for the other edta donor atoms) to be considered as coordinated. 

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