Zirconium, tris structure

Zirconium, tetrakis(acetylacetonate)-stereochemistry, 32 Zirconium, tetrakis(acetylacetone)-stercochemistry, 94 Zirconium, tris(phcnylenedithio)-structure, 63 Zirconium chloride (ZrCl) structure, 27 2.r6Cli2 structure, 27 Zirconium iodide Zr6li2... 

Zirconium tris-neopentyl surface complex 1 was synthesized by the sublimation of tetra-neopentylzirconium complex onto the surface of partially dehydroxylated silica at 500°C [26, 27] and fully characterized by IR, NMR, EXAFS, elemental analysis, and gas quantification methods as well as chemical methods [3, 28, 29]. Furthermore, in order to confirm its surface structure, the grafting experiment was carried out with deuterated silica and tetra-neopentylzirconium. Evolution of 1 mol of deuterated neopentane per mole of grafted zirconium proved that there is a single bond between zirconium and oxygen. This monopodal surface structure was further confirmed by EXAFS experiment with 1. 

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

Zwitterionic structures with a borate anion covalently attached to a cyclopentadienyl donor can be obtained by a number of synthetic approaches. In the known compounds, the means by which the borate is tethered to the ring has a significant impact on the properties of the zwitterions. In particular, the length of the tether connecting the ring with the borate is crucial for the stability and intramolecular ion-ion contacts. For example tris cyclopentadienyl zirconium betaine complex in which boron atom is directly bonded to Cp can be generated from boron substituted cyclopentadienyl anion (equation 21). ... 

The pyrophosphate of uranium(IV) has been obtained and the structure determined to belong to the ZrP207-type structure. " Octahedral sites in the zirconium phosphates can accommodate U, as exemplified by the Na dizirconium tris(phosphate) structural family ([NZP]). An end member in this study was monoclinic KU2Zr(P04)3, which contains nine-coordinate Compounds of the general formula MU2(P04)3 have been reported for... 

The crystal structure of [(f-Bu3-CO)2ZrCl3 Li(OEt2)2] (295) is shown in Fig. 42, and consists of two chloride groups bridging lithium and zirconium atoms. The overall stereochemistry of the zirconium center is pseudotrigonal bipyr-amidal and the bulky tri-fm-butylmethoxide ligands occupy the least-crowded equatorial sites. 

The zwitterionic tris(cyclopentadienyl)zirconocene complex 1213 is obtained by treatment of Cp2ZrCl2 with the lithium, sodium salt of the B(C6F5)3-substituted borato-Gp dianion according to Scheme 286.930 The X-ray crystal structure of this complex reveals that the three 75-cyclopentadienyl ligands are in a nearly trigonal-planar coordination around zirconium with a pronounced Zr-F-G(aryl) coordination perpendicular to it this Zr-F-G(aryl) coordination is persistent in solution based on solution NMR studies. 

By treatment of 159 and 164 with methyllithium, Erker obtained 167 and 168 in 57% and 80% yield, respectively the latter was also characterized by X-ray-crystallography (Scheme 27). Treatment of 167 and 168 with 1 equiv of tris(pentafluorophenyl)-borane caused a methyl transfer with formation of cationic zirconium complexes 169 (91%) and 170 (95%) 169 was also structurally characterized. Addition of a second equivalent of the borane gave dicationic 171 in 93% yield. Treatment of 171 with dichloromethane resulted in an immediate reaction to give 172, which also was structurally characterized. The similar complex 173 was obtained by treatment of 164 with tris(pentafluorophenyl)borane (88%). Addition of acetonitrile to 171 gave 174 (89%), and with 2,6-dimethylphenylisonitrile, 175 was formed in 81% yield. Complexes 169, 170, and 172 show an interesting dynamic NMR behavior corresponding to... 

A completely different rationale for the stereochemical outcome of aldol additions relies on open-transition-state models. These involve anti-periplanar orientation of enolate and carbonyl group, in contrast with their syn-clinal conformation assumed in the six-membered cyclic transition states. Open-transition-state structures have been proposed to offer a rationale for those aldol additions that give predominantly syn products, irrespective of enolate geometry [90]. This outcome has been observed in aldol reactions of tin and zirconium enoiates and of naked enoiates generated from enolsilanes by treatment with tris(diethylamino)sulfonium difluoro-methylsiliconate [70]. As shown in Scheme 1.12, the driving force for the... 

The X-ray crystal structure of the tris( n4-naphthalene)zirconate(2-) anion as the bis[K(2,2,2-crypt)] salt has been determined, revealing a trigonal prismatic coordination geometry of local Csv symmetry about the zirconium atom, as defined by the mid-points of the C-C vectors of the coordinated diene units, similar to that eviously observed for the isoelectronic tris(ii i-butadiene)molybdenum complex. 

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