Zirconium tetrakis

The thermogravimetric curves of several europium compounds and tetracosane are shown in Figure 3. The thermograms of some of the tris rare earth thd chelates and the tetrakis zirconium compound are presented in Figure 4, and those of the tris fod chelates are shown in Figure 5. 

Zirconium, tetrakis(acetylacetonate)-stereochemistry, 1, 32, 94 Zi rconium, tris(phenylenedithio)-structure, 1, 63 Zirconium alkoxides oligomeric structure, 2,346 Zirconium chloride... 

One method of solving the kinetics dilemma is well known in coordination chemistry that is, start with a labile metal ion and render it inert during the course of the synthetic reaction. We have accomplished this in the case of zirconium(IV) by starting with tetrakis(salicylaldehydo)zirconium(IV), which is quite labile, and polymerization with 1,2,4,5-tetraaminobenzene in a Schiff-base condensation reaction in situ (6). The polymeric product contains a "double-headed" quadridentate ligand, which is much more inert to substitution. However, 1,2,4,5-tetraaminobenzene has become very expensive. Therefore, the synthesis of a zirconium polymer with 3,3, 4,4 -tetraaminobiphenyl (commercially 3,3 -diami nobenzidine) with zirconium salicylaldehyde, Zr(sal)4 (7) has been undertaken as shown below ... 

Stanna[l]zirconocenes have been prepared by an alternative approach, taking advantage of the protic acidity of cyclopentadienylstannanes to bring about the acidolysis of tetrakis(dimethylaminyl)zirconium (Equations (119) and (120)).323... 

Gennamiun(II) sulfide, 4419 Goldail) sulfide, 0116 Iron disulfide, 4401 lron(ll) sulfide, 4400 lron(lll) sulfide, 4404 Manganese(ll) sulfide, 4706 Manganese(lV) sulfide, 4707 Merciuy(ll) sulfide, 4607 Molybdemun(lV) sulfide, 4719 Potassium sulfide, 4670 Rhenium(Vll) sulfide, 4891 Ruthenimn(lV) sulfide, 4895 Samarium sulfide, 4899 Silver sulfide, 0026 Sodimn disulfide, 4812 Sodimn polysulfide, 4813 Sodimn sulfide, 4811 Strontimn sulfide, 4901 Tantalum(lV) sulfide, 4903 Tetrakis(butylthio)uranimn, 3731 Thorium oxide sulfide, 4826 Tin(II) sulfide, 4900 Tin(IV) sulfide, 4902 Titaniiun(IV) sulfide, 4904 Uranium(IV) sulfide, 4905 Zirconium oxide sulfide, 4827... 

Stabilized compounds are inherently more stable then those compounds, which contain /1-hydrogens. Therefore, catalysts where the -positions are blocked, are preferred (8). Examples are zirconium tetrakis(trimethylsilylmethyl) or hafnium tetrakis(trimethylsil-ylmethyl). Catalyst supports are porous alumina with an amount of 0.5% of silica. 

Catalyst Zirconium tetrakis(trimethylsilylmethyl) a TS Tensile strength b SA Sand wheel abrasion... 

Figure 4 Structures of (a) tetrakis(l,3-diphenyl-l,3-propanedionato)zirconium(IV) and (b) tetrakis(2,4-pentanedionato)zirconium(IV). Dimensions of the coordination polyhedra are averaged in accord with approximate I>2-222 symmetry. Distortions of the square antiprisms involve slight folding of the quadrilateral faces about the indicated face diagonals (reproduced by permission from reference 226)...

Table 14 Averaged Metal-Oxygen Bond Lengths (A) in Tetrakis(oxalato) Complexes of Zirconium(IV)...

Zirconium(IV) forms a tetrakis chelate with the hydroxamate-related l-oxy-2-pyridonate... 

Zirconium(IV) and hafnium(IV) tetrakis(tetrahydroborates) M(BH4)4 are of interest as extremely volatile, covalent complexes that contain tridentate BH ligands and exhibit rapid intramolecular exchange of bridging and terminal hydrogen atoms. 4,615 These compounds were prepared initially from NaMF5 (M = Zr or Hf) and excess A1(BH4)3 (equation 53),616 but they are obtained more conveniently from the reaction of the anhydrous metal tetrachloride with excess lithium tetrahydroborate (equation 54), either in the solid state617,618 or in the presence of a small amount of diethyl ether.619... 

Tetrakis(acetylacetonato)zirconium, which has a square antiprism structure, shows marked smoke-retarding properties in poly(vinyl chloride)5 and it is effective as an accelerator in anhydride-cured epoxy resins.26... 

The first soluble Schiff base coordination polymer was reported by Archer et al. in 1985,31 which was prepared by condensation of 1,2,4,5-tetra-amino benzene (TAB) with tetrakis(salicyladehydato)zirconium(IV) (Zr(sal)4) in dry dimethyl sulfoxide (Fig. 15). The polymer has a number-average molecular weight of up to 4.9 X 104 based on inherent viscosity, gel permeation chromatography, and elemental analyses and shows no decomposition at temperature <500°C. 

High-coordination-number complexes of 0-keto-enolates continue to be obtained with the metals such as zirconium(IV),8 hafnium(IV),8 cerium(IV),9 and the lanthanons(III),10 the last being tetrakis anionic species. At least one example of a volatile tetrakis 0-keto-enolate salt has been reported,11 Cs[Y(CF3-COCHCOCF3)4]. The ionic charge on the 0-keto-enolate complex has been shown to produce12 a high field nuclear magnetic resonance for anions and low field shifts for cations, relative to the positions observed for the neutral species. 

Iodotris(2,4-pentanedionato) zirconium (IV) has been prepared by reaction of zirconium (IV) iodide with 2,4-pentanedione in isopropyl ether and by the ligand-exchange reaction between zirconium (IV) iodide and tetrakis(2,4-pentane-dionato)zirconium(IV) in tetrahydrofuran.7 The latter approach, which yields a higher-purity product, is described here. 

A solution of 3.81 g. (0.00636 mole) of anhydrous zirconium (IV) iodide in 250 ml. of tetrahydrofuran is prepared in a glass-stoppered Erlenmeyer flask equipped with a sidearm and stopcock (similar to flask B in Fig. 5). While a stream of argon.is passed through the stopcock and over the surface of the solution, 9.31 g. (0.0191 mole) of tetrakis(2,4-pentanedionato)zir-conium(IV) [zirconium(IV) acetylacetonate]19 is added. The solution is stirred for an hour at room temperature, and then... 

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