Adamantane cage

The tetrameric zinc anion [Zn4(//-ScPh)r,(ScPh)4]2 has been structurally characterized as the first example of a Zn4Se4 adamantane cage-type structure.594 A further example was characterized by Bochmann and co-workers as part of a study of polymetallic zinc selenophenolates, in this case with chlorides replacing the terminal selenophenolates, [Zn4(/u-SePh)6Cl4]. Octameric zinc species were also characterized with either chloride or phosphine ligands resulting in anionic and neutral complexes respectively, [Zn8(/x-SePh)12Cl4]2 and Zn8(yu-SePh)12(SePh)2 (P Pr3)2.301... 

Dimeric (Me2AuCl)2 has been used to close the cationic adamantane cage of a bowl-shaped iVV-donor ligand with a [m-Me2Au]+ unit. The two chlorine atoms are accommodated in the [m-Me2AuGl2] counterion (Equation (7)).34... 

Reaction of CsOH, H2S and SnS2 in water yields the Cs+ salt of [Sn1004S2o]8"-303 In this cluster the Sn10S20 atoms are arrayed as in (10a), and the four O atoms are contained within the four adamantane cages, but closer to and bonded to the faces of the (Sn )6 octahedron. The O atoms are not bonded to Sn°. The Sn atoms have strongly distorted (ii3-0)3( r3-S)3 octahedral coordination. 

If the hydrocarbon radical cation has a definitive structure, proton loss occurs from one particular, well-defined position and these transformations are more selective than the alternative C-H abstractions from alkanes with radical reagents (Eq. 2). For example, C-H substitutions of the adamantane cage with radical reagents always give mixtures of 1 and 2-substituted adamantanes [2], As the adamantane radical cation (4) has one single structure, proton transfer from the radical cation to the solvent occurs highly selectively. Scheme 2 shows the geometry of 4 and the structure of the complex of the adamantane radical cation with acetonitrile (S) where the tertiary C-H bond is already half-broken. 

There are several (sometimes interconvertible) cyclo-phosph(III)azanes, illustrated in Scheme 47. Bicyclic, tricyclic, adamantane cage, and more complex structures can be obtained by minor variations of the reaction conditions, also depending on the nature of the substituents at phosphorus and nitrogen sites. For reviews see Reference 214. 

X-Ray structure analysis of 14a, 15a, and 15b has established the central adamantane cage which is characteristic of the unsolvated triamides [6, 8], Whereas there is little appreciable interaction between the periphery of the molecules in the structures of the t-butyl substituted species 15a and 15b, the two-coordinate Li-atoms are "internally solvated" by the phenyl groups in the chiral triamide 14a (Fig. 3). The orientation of the aryl rings towards the puckered six-membered (LiN)s-ring and the short contact between Li and C7 indicates a direct interaction between the metal atoms and the periphery. 

Figure 1.3.6 The highly distorted diamondoid net observed in the 2-fold interpenetrated structure of SbCI3(p-diacetylbenzene) with a diamondoid cage in black (W. A. Baker, D. E. Williams, Acta Crystallogr., Sect. B 1978, 34, 1111) (left). The observed diamondoid cage (center) is compared with the undistorted adamantane cage as in diamond (right).

Figure 1.3.8 The structures of diamond (dia) (left) and lonsdaleite (hexagonal diamond, Ion) (right) showing in grey the natural tile with 10 vertices for dia (adamantane cage) with transitivity [1111] and the two natural tiles with 8 and 12 vertices for Ion with transitivity [1222].

Pressure exerted on atom confined in an adamantane cage 302... 

The atoms of the adamantane cage are not totally enclosed. Their volumes v(C) and u (H), necessary for the calculation of the atomic pressures, are determined by the intersection of the 0.001 au density envelope with the interatomic surfaces bounding the atom. This volume contains 99.991% of the density of a methine carbon atom, for example. Contributions to the surface integrals vs X), beyond their intersection with the 0.001 envelope, should make negligibly small contributions to the atomic pressures. 

Me2SiCl2 which gives the cage compound 65 which, on heating above 120°C, dimerizes to the more stable adamantane cage of 58 (equation 62)78. 

A substituted triazaadamantane, 2,4,10-trinitro-2,4,10-triazaadaman-tane, was made a few years ago by Nielsen [18J. Its synthesis showed that a methine (CH) surrounded by nitramines in an adamantane cage is chemically stable, a matter that had previously been the subject of debate. There are four such groupings in HNZADA. Otheivvise. the local connections are much the same as in HMX and RDX. Molecular mechanics model-building shows that the nitramines are no more crowded than in HMX and RDX, so there is reason to expect that this target molecule will not be especially sensitive or readily subject to chemical deterioration. 

The observation of 1-t rt-butyladamantane in the superacid-catalyzed reactions of adamantane with butenes provides unequivocal evidence for the (j-alkylation of adamantane by the tert-huty cation. As this involves an unfavorable sterically crowded tertiary-tertiary interaction, it is reasonable to suggest that similar (j-alkylation can also be involved in less strained interactions with secondary and primary alkyl systems. Although superacid-catalyzed alkylation of adamantane with olefins occurs predominantly via adamantylation of olefins, competing direct cr-alkylation of adamantane can also occur. As the adamantane cage allows attack of the alkyl group only from the front side, the reported studies provide significant new insight into the mechanism of electrophilic reactions at saturated hydrocarbons and the nature of their carbocationic intermediates. 

The action of heat on P4(8iMe2)3 secures transformation to the adamantane-type compound, (Me28i)6P4 (9.238), as in Equation 9.231. It is stable up to 400°C. A similar adamantane cage with the 8i and P atoms reversed can be obtained as indicated in Equation 9.239 [31]. 

Figure 4 (a) Perspective views of the structure of a single adamantane cage with TUBA connections between cadmium ions, (b) View of the structure of 4d2DMF, showing the fourfold interpenetration of diamondoid networks. (Reprinted with permission from Ref 24. Copyright (2009) American Chemical Society.)... 

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