Adamantane structure

A unique feature of such DNA-directed self-assemblies is their site-selective immobilization, which makes it possible to construct well-defined nanostructures. On the other hand, the possibility of the introduction of a vast number of substitutes (like peptidic sequences, nucleoproteins, of hydrophobic hydrocarbon chains) to an adamantane core (adamantyl) makes such a process capable of designing steric colloidal and supramolecular conformations by setting hydrophobic/hydrophilic and other interactions. In addition, the rigidity of the adamantane structure can provide strength and rigidity to such self-assemblies [150]. 

The reaction of this LijP with Me2SiCl2 in a molar ratio of 1 2 progresses very slowly in DME. After 12 hours at 0°C the suspension of the reaction mixture still has a light brown color. It is only after a 4-hour heating at 84° C that this color slowly clears up. During the reaction, compound 10 (adamantane structure) is formed, as well as small quantities of by-products. There was no indication of the formation of P(SiMe2)3P. 

In addition, the butylated compounds ClEt2SiP(SiEt2)2—PSiEt2Bu and (SiEt2)4P3SiEt2Bu (the butylated derivative of 22), and trace amounts of 13 are formed. A compound with the adamantane structure corresponding to compound 10 or to its precursor 11 can be excluded with certainty. 

The adamantane structure is unique as it combines three annullated cyclohexane subunits in a nearly spherical overall shape and, as such, it can be regarded as a section of the diamond crystal lattice578. Due to this property, adamantane and other diamondoid molecules are popular as model compounds for synthetic and spectroscopic purposes579 780. 

Heterocyclic Compounds with Adamantane Structure Z. Kafka and V. Galik, Chem. Listy, 1978, 72, 509-542. 

Very recently it was possible to synthesize two basic adamantanes of the formula (HSi)4S6 and (HSi)4Se6. They were made by reacting HSiCl3 with (H3Si)2E (E = S, Se). An X-ray structure determination proved the expected adamantane structure for (HSi)4S6 and spectroscopic investigations left no doubt that (HSi)4Se6 has the same structure (94). 

Finally, there are polycyclic P—N compounds such as those shown in Fig. 10-14. Note that (a) which has an adamantane-type structure and (c) are isomers when R = Me, the adamantane structure is thermally stable, but when R = Me C, the (a) structure converts to the (c) structure on heating for 12 days at 157°C. 

The tetraphosphorus(III)hexaazaadamantane derivative, P4(NMe)6, is obtained from phosphorus trichloride and methylamine, and a tricyclic compound of composition P4(NPT)6 is formed from ClP(NPri )2PNPri SiMcs by elimination of Me3SiCl. It isomerizes on heating into the adamantane structure. Another tricyclic compound, P4(NBfr)6 with nonadamantane structure is formed by reacting [ClPNBfr]2 with [(LiNBu )PNBfr]2- ... 

With the exception of the Mn(IV) adamantane, all the macrocyclic complexes discussed above are at oxidation levels much below those likely to be present in functional OEC states. For this reason they are unlikely to mimic the spectroscopic properties of the active states unless they can be oxidized (an unfavorable process for seven-coordinate Mn(II) 248)). However, the variable and sometimes irregular geometries observed make these complexes valuable as calibrants for X-ray absorption studies 233, 239). The low symmetry observed in some of the macrocyclic tetramanganese structures and predicted for the OEC highlights that the differences among the four structural classes illustrated in Fig. 50 are not as great as it first appears and interconversions may be possible without major disruption of the coordination environment. The planar dimer-of-dimers structure, twisted or folded slightly, becomes a butterfly structure and if this is folded sufficiently a cubane results. The disposition of the Mn atoms in the cubane is identical to that in the adamantane structure. 

Cubane or adamantane structures were postulated 179) for compounds of stoichiometry Fe4X3(OCH3)g, the fits of magnetic data to a Heisen-... 

Structures of to date nonbiological Fe-S clusters (A) the thioprismane structure (B) basket-handle structure (C) monocapped prismatic structure (D) adamantane structure (E) circular FeigSso core unit. 

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