Zirconium complexes water

In particular, they found enhanced bonding between metal surfaces and resins such as acrylics (solvent- and water-based), epoxy chlorinated rubbers, silicones, and polysulphides. It was noted that titanium complexes caused colouration with phenolics, whilst zirconium complexes did not. 

Cationic P compounds exhibit several modes of reactivity, including coordination to Lewis acids oxidation by acids, water, and alkyl chlorides and substitution of the stabilizing phosphine ligands by stronger donors (Scheme 17). Some of these P and As cations have also been shown to be useful sources of P and As ions that provide zirconium complexes (12) containing unique square-planar Pn environments (equation 22). ... 

The zirconium and hafnium complexes of trifluoroacetyl-acetone are white crystalline solids, insoluble in water but soluble in benzene, cyclohexane, and carbon tetrachloride. The hafnium complex melts at 128 to 129° and the zirconium complex at 130 to 131°. The complexes have been subjected to gas-phase chromatography and may be sublimed at 115° at a pressure of 0.05 mm. The proton magnetic resonance spectra of the compounds dissolved in carbon tetrachloride show single peaks in the methyl and methylene regions. The peaks appear at 2.20 and 6.00 p.p.m. (5) relative to tetramethylsilane (internal reference) for the zirconium complex and at 2.20 and 5.97 p.p.m. for the hafnium complex. 

Zrrconocene, ZrCp2, generated in situ from zirconocene derivatives, mediates diverse ring-closures. Thus treatment of 2,4,4-trimethyl-l,6-heptadiene with butyllithium and Bu2ZrCp2 yields the zirconium complex 218, which gives 1,1,3,3,5-pentamethylcyclopentane on aqueous work-up (equation 111). The reaction of 1,7-octadiene with butyknagnesium chloride and a catalytic amount of zirconocene dichloride, followed by water, gives frons-l,2-dimethylcyclohexane (219) in excellent yield (equation 113) similarly, the diene ether 220 affords the cyclopentane derivative 221 (equation 113). ... 

OC H8, Furan, tetrahydro-, hafnium, niobium, scandium, titanium, vanadium, and zirconium complexes, 21 135-139 0H2, Water, cobalt complex, 21 123-126... 

The use of zirconium complexes derived from tartramides 3.19 in asymmetric epoxidation of homoallylic alcohols does not result in any improvement over the related to titanium analogs [808]. A zirconium complex prepared from Zr(Otert-Bu)4 and (S,S,S)-triisopropylam3ne 3.22 in the presence of water catalyzes the asymmetric ring opening of meso-epoxides by /-PiMe2SiN3 (ee 85%), while related titanium complexes are less efficient [805,831]. 

Aryne complexes of late transition metals are very reactive towards both nucleophiles (amines, alcohols, water) and electrophiles (iodine). They also undergo insertion reactions with CO, alkenes and alkynes,but while the behaviour of ruthenium complexes is somewhat similar to that of titanium or zirconium complexes, the reactivity of nickel complexes is rather different [6,8]. Examples of these reactions that are particularly interesting for the purposes of this chapter are shown in Schemes 8 and 9. Ruthenium complex 33 undergoes insertion of a molecule of benzonitrile,benzaldehyde or di(p-tolyl)acetylene to yield met-allacycles 40,41 and 42, respectively (Scheme 8). Further insertion of a second unsaturated molecule into these metallacycles has not been observed [25,27]. 

The reactivity of the side-on bound N2 ligand in the zirconium complex 19-Zr was further probed by addition of water. This leads to the rapid protonation of the [N2]" ligand to form hydrazine and a zirconocene bis (hydroxide) [(r] -C5Me4H)2Zr(OH)2] (Scheme 10). However, any attempts to observe intermediates along this reaction pathway by adding substoichiometric quantities of H2O failed. Addition of EtOH affords N2H4 and [(Ti -C5Me4H)2Zr(OEt)2] (Scheme 10). 

Yamashita Y, Ishitani H, Shimizu H, Kobayashi S. Highly anti-selective asymmetric aldol reactions using chiral zirconium catalysts. Improvement of activities, structure of the novel zirconium complexes, and effect of a small amount of water for the preparation of the catalysts. J. Am. Chem. Soc. 2002 124 3292-3302. 

Peshkova, V.M., Mel chakova, N.V., and Zhemchuzhin, S.G. (1961) Complex formation in the benzoyl-acetone [l-phenylbutane-l,3-dione]-zirconium-benzene-water system and the hydrolysis of zirconium ions. Russ. ). Inorg. Chem., 6, 630-634 (English translation). 

Kobayashi has reported a remarkable series of chiral Zr(IV) complexes as catalysts for enantioselective aldol addition reactions [136, 137]. These are readily prepared from 3,3 -dihalo-BINOL derivatives and Zr(OtBu)4. The putative zirconium complex 266 is reported to mediate the formation of anti aldol adducts with excellent diastereo- and enantioselectivity (Scheme 4.33). It is noteworthy that under optimal conditions, the reactions are carried out in aqueous propanol/toluene solvent mixtures. As such, the process is tolerant of and indeed thrives in, the presence of water. A demonstration of its use was reported in the synthesis of khafrefungin (269), an inhibitor of fungal sphingolipid synthesis [137]. 

The concentration of fluoride in drinking water may be determined indirectly by its ability to form a complex with zirconium. In the presence of the dye SPADNS, solutions of zirconium form a reddish colored compound, called a lake, that absorbs at 570 nm. When fluoride is added, the formation of the stable ZrFe complex causes a portion of the lake to dissociate, decreasing the absorbance. A plot of absorbance versus the concentration of fluoride, therefore, has a negative slope. 

Hydroxyl Compounds. The aqueous chemistry of zirconium is complex, and in the past its understanding was compHcated by differing interpretations. In a study of zirconium oxide chloride and zirconium oxide bromide, the polymeric cation [Zr4(OH)g (H20)jg was identified (189) the earlier postulated moiety [Zr=0] was discarded. In the tetramer, the zirconium atoms are coimected by double hydroxyl bridges (shown without the coordinating water molecules) ... 

In situ densitometry has been the most preferred method for quantitative analysis of substances. The important applications of densitometry in inorganic PLC include the determination of boron in water and soil samples [38], N03 and FefCNfg in molasses [56], Se in food and biological samples [28,30], rare earths in lanthanum, glass, and monazite sand [22], Mg in aluminum alloys [57], metallic complexes in ground water and electroplating waste water [58], and the bromate ion in bread [59]. TLC in combination with in situ fluorometry has been used for the isolation and determination of zirconium in bauxite and almnimun alloys [34]. The chromatographic system was silica gel as the stationary phase and butanol + methanol + HCl -H water -n HF (30 15 30 10 7) as the mobile phase. 

A particulate gel breaker for acid fracturing for gels crosslinked with titanium or zirconium compounds is composed of complexing materials such as fluoride, phosphate, sulfate anions, and multicarboxylated compounds. The particles are coated with a water-insoluble resin coating, which reduces the rate of release of the breaker materials of the particles so that the viscosity of the gel is reduced at a retarded rate [205]. 

ZnxZryFz. A fluoro complex of zirconium, ZrF62, and an ammine complex of zinc, ZnfNFF), have been used to grow ZnxZryFz films on silicon. The Zn/Zr/F ratio was 0.08/1/0.32, and the films contained hydroxyl groups and physisorbed water.128... 

Zirconium and hafnium tetraalkoxides are highly reactive compounds. They react with water, alcohols, silanols, hydrogen halides, acetyl halides, certain Lewis bases, aryl isocyanates and other metal alkoxides. With chelating hydroxylic compounds HL, such as j8-diketones, carboxylic acids and Schiff bases, they give complexes of the type ML (OR)4 these reactions are discussed in the sections dealing with the chelating ligand. 

Because K2HfF6 is —1.7 times more soluble in water than K2ZrF6,528 zirconium and hafnium can be separated by fractional crystallization of the hexafluorometallates. This approach is used on an industrial scale in the USSR.286 Conductance measurements on aqueous solutions of M2MF6 (M = K, Rb, or Cs) indicate very little hydrolysis of the [MF6]2- ions.529 Alkaline hydrolysis of potassium and ammonium fluorozirconates yields crystalline M ZrF3(0H)2-H20 complexes, which are easily dehydrated to M ZrF3(OH)2. 

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