Iodine, crystal structure

Physical Properties. The absorption of x-rays by iodine has been studied and the iodine crystal structure determined (12,13). Iodine crystallizes in the orthorhombic system and has a unit cell of eight atoms arranged as a symmetrical bipyramid. The cell constants at 18°C (14) are given in Table 1, along with other physical properties. From the interatomic distances of many iodine compounds, the calculated effective radius of the covalendy bound iodine atom is 184 pm (15). 

The catalytic subunit then catalyzes the direct transfer of the 7-phosphate of ATP (visible as small beads at the end of ATP) to its peptide substrate. Catalysis takes place in the cleft between the two domains. Mutual orientation and position of these two lobes can be classified as either closed or open, for a review of the structures and function see e.g. [36]. The presented structure shows a closed conformation. Both the apoenzyme and the binary complex of the porcine C-subunit with di-iodinated inhibitor peptide represent the crystal structure in an open conformation [37] resulting from an overall rotation of the small lobe relative to the large lobe. 

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... 

With boron and an appropriate amount of some sort of alkaline metal halide present in the starting materials for the solid-state reactions, then we obtain zirconium cluster materials belonging to the 6-14 family. Single-crystal X-ray data of products from iodine-rich reactions were used to determine the crystal structures of Na[(Zr6B)Cl3.87(5)lio.i3], and Cs[(Zr6B)Cl2.i6(5)lii.84] [21]. Both phases... 

Fig. 5 Scatterplot derived from the CSD reporting the N- I-C angle (deg) vs. the N- I distance (A) for crystal structures containing intermolecular N- I contacts only error-free and non-polymeric structures containing single-bonded iodine atoms and showing no disorder with R < 0.06 are considered. The scatterplot clearly demonstrates the high directionality of the N- I XB...

An X-ray crystal structure determination of calciferol (vitamin D-2,71) showed that steric crowding in the s-cis diene system resulted in a twisted conformation with a dihedral angle of 53° [59], On irradiation with a mercury lamp, it was partially converted into ergosterol (72) and tachysterol (73) [60, 61]. When a solution of calciferol in light petroleum containing a trace of iodine was exposed to diffuse daylight, the vitamin was photoisomerized to (74) [62],... 

The compound 4(Ph3SbI)2OI2 is obtained by the addition of I2 in acetonitrile/water to a solution of triphenyl-antimony. The crystal structure contains a one-dimensional chain 53 and (Ph3SbI)20 molecules which are not coordinated to I2. In the ID chain, the distance between the iodine of the (Ph3SbI)20 molecule and the diiodine... 

Figure 7.19. A packing drawing of iodine molecules in its crystal structure.

The synthesis of the heterocyclic diiodides can be tricky (Scheme 8). Direct iodination of quinoline was reported by Kiamuddin et al. [59] to give 5,8-di-iodoquinoline. Their procedure did not furnish any products according to Bunz et al., but classical electrophilic iodination leads to a single product that was identified not to be the 5,8-isomer but 3,6-diiodoquinoline, according to the X-ray crystal structure of a diethynylated derivative [60]. 

In these latter compounds, the hypervalent iodine may be associated with oxyanions such as perchlorate, trifluoroacetate, and triflate, as verified by the crystal structure of the trifluoroacetate derivative (41). It seems likely that the mode of binding of... 

Shi et al. [68] have studied iodine adsorption on Ag using atomic-resolution electrochemical scanning turmehng microscopy (ECSTM) method. Distinctly different iodine adlayer structures and surface diffusion behavior were observed on mechanically polished pc-Ag in comparison with those obtained on single-crystal electrodes. 

Among the widely studied [AuX(PR3)] (X = halogen, PR3 tertiary phosphine) [AuBrL] (L = 2-methylphenylphosphine) crystallizes as a folded chain [65]. Chains of the tetrahydrothiophene and tetrahydroselenophene complexes [AuX(EC4H8)] (E = S, X = Cl, Br or I E = Se, X = I) [66, 67] exhibit different patterns. In the crystal structure of the tetrahydrothiophene compounds [AuX(SC4H8)] (X = Cl, Br) neutral units associate, whereas the structure of the iodine complexes consists of Aul2 and... 

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