Crown center

Turning our attention to the Turret Room of Da ath, to the right of the eastern serpent-framed window, there is a purple pull-rope. It is used to lower or raise a trapdoor in the ceiling ornamented with the Prithivi-Prithivi symbol of the Mercury center, and from it comes a ladder that enables one to ascend to the battlements of the tower, which correspond to the crown center, the Sahasrara-padma, the thousand-petaled Lotus. 

Most of the liquid crystals discussed in this section bear a diaza[18]crown-6 40, a 4,4 -diaminodibenzo[18]crown-6 41, or a thia crown ether 42 in their center (Scheme 23). Substitution in 40 and 41 is conveniently feasible on the nitrogen atoms by formation of a Schiff base or an aza compound (in the case of 41) or by N-alkylation or -acylation (in the case of 41). O-Alkylation and -acylation of 42, which are difficult to obtain, open a path to thia crown centered liquid crystals. 

The hotel was renamed the Hyatt Regency Crown Center in 1987. It changed owners and was renamed the Sheraton Kansas City Hotel at Crown Center in December 2011. 

See Sheraton Kansas City Hotel at Crown Center, ... 

Federal Motor Carrier Safety Administration Two Crown Center 1745 Phoenix Blvd., Ste. 380 Atlanta, GA 30349 (678) 284-5130 Fax (678) 284-5146... 

Cone Up. Cone-up tank bottoms are built to have a high point in the center of the tank (Fig. 7b). This is accompHshed by crowning the foundation and constmcting the tank on the crown. The slope is limited to about 1—2 in. (2.5—5 cm) for every 10 ft (3 m) of mn. Therefore, the bottom may appear flat, but heavy stock or water tends to drain to the edge where it can be removed almost completely from the tank. 

Chelation itself is sometimes useful in directing the course of synthesis. This is called the template effect (37). The presence of a suitable metal ion facihtates the preparation of the crown ethers, porphyrins, and similar heteroatom macrocycHc compounds. Coordination of the heteroatoms about the metal orients the end groups of the reactants for ring closure. The product is the chelate from which the metal may be removed by a suitable method. In other catalytic effects, reactive centers may be brought into close proximity, charge or bond strain effects may be created, or electron transfers may be made possible. 

The elements of gear teeth common to all gears are tooth surface and profile, flank, top and bottom land, crown, root and pitch circle, gear center, line of centers, pitch point, line of action, line of contact, and point of contact. Figure 57.27 labels many of the common gear tooth elements. Figure 57.28 labels the common rack tooth elements. 

Zollinger and coworkers (Nakazumi et al., 1983) therefore supposed that the diazonium ion and the crown ether are in a rapid equilibrium with two complexes as in Scheme 11-2. One of these is the charge-transfer complex (CT), whose stability is based on the interaction between the acceptor (ArNj) and donor components (Crown). The acceptor center of the diazonium ion is either the (3-nitrogen atom or the combined 7r-electron system of the aryl part and the diazonio group, while the donor centers are one or more of the ether oxygen atoms. The other partner in the equilibrium is the insertion complex (IC), as shown in structure 11.5. Scheme 11-2 is intended to leave the question open as to whether the CT and IC complexes are formed competitively or consecutively from the components. ... 

In the first half of the nineties, there has been a continuing trend from synthetic studies of classical crown ethers towards the polyazamacromolecules and the introduction of multiple heteroatoms, including most recently the metal atom centers. 

The Fe6 rings have also been extensively studied. [Fe6(p2-OMe)12(dbm)6] (32,33) is a neutral species but in the solid state it crystallizes with NaCl to give [Na c Fe6(p2-OMe)12(dbm)6]+. The Na+ ion is trapped in the center of the iron wheel, which acts like a crown ether complexing an alkaline ion. 

Co2(CO)8 with HC1 gas in the presence of 15-crown-5 and water in toluene. This led to a complex species which included seven-coordinate pentagonal bipyramidal Co11 centers (98) which included the metal ion in the macrocyclic polyether.422... 

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