Adamantane-like structures

The unexpectedly complex product was isolated as an almost colourless air-stable powder, and a single-crystal X-ray analysis showed that it had the molecular adamantane-like structure (5). This is very similar to the structure of the iso-electronic compound P4O10 (p. 504). 

Oxygen-centered phosphanides are accessible by hydrolysis of the phospha-nides as shown for the oxygen-centered phosphanide 73 of the formula [Sr40- P(SiMe2Prl)2 6] with an Sr4P6 adamantane-like structure as shown in Eq. (7) [74], The strontium atoms are coordinatively saturated by agostic interactions to the silicon-bonded alkyl substituents. 

P2O5 actually exists as P4O10, an adamantane-like structure. 

Binary oxides of phosphorus, arsenic and antimony are polycyclic compounds, e.g. E4O6 (E = P, As, Sb), with an adamantane-like structure. Monocyclic... 

The chemistry of hexamethylenetetramine, or hexamine (70), has been reviewed thoroughly (B-61MI22000, p. 688,59HC(13)1, p.545,79S161). The discussion below summarizes these reviews. Hexamethylenetetramine has a symmetrical adamantane-like structure, and is quite stable. It is hydrolyzed by hot mineral acid to formaldehyde and the appropriate... 

Tetrodotoxin, an extremely poisonous heterocycle present in Japanese puffer fish (various species of Spheroides), exerts its action by blocking the sodium ion channels in the peripheral nervous system. Chemically it has an adamantane-like structure, namely octahydro-12 - (hydroxymethyl) - 2 - imino-5,7,9,1 Oa-dimethano- 10aH-[ 1,3] -dioxo-cino-[6,5-d]pyrimidine-4,7,10,11,12-pentol. When chemically dehydrated, it rehydrates in dilute acid.73 Methanol, and ammonia, can add similarly. Because 2-amino-1,6-dihydropyrimidine forms the central part... 

Figure 20.4.5 shows the crystal structure of [Cu l,4-C6H4(CN)2 2]BF4. The nodes are the four-connected Cu atoms, each being coordinated tetrahedrally by N=C-C6H4-C=N ligands as rods. The adamantane-like structure unit is shown in Fig. 20.4.5(a), and repetition of such units along a twofold axis leads to fivefold interpenetration. The remaining space is filled by the BF ions. 

Left) Two interpenetrating networks in the crystal structure of ice-VII. (Right) Two views of an adamantane-like structural unit. 

The only monothiol studied, thiophenolate (PhS ), forms pink tetrahedral [Mn(SPh)4]2, isolated as [NR4]+ and [PPh4]+ salts,320,321 and a red-orange, tetrameric anion [Mn4(SPh)l0]2, which has the adamantane-like structure (125)320 (which is, of course, a small fragment of the zinc blende or diamond structure of ]3-MnS). Each of these species has parallels in the other transition metals. 

The sesquisulfides and sesquiselenides, are tetramers, (RSnXi.s)4, with adamantane-like structures.5 23> 24... 

Cyclization of organoaluminums proceeds via intermolecular and intramolecular exchange. The bis-hydroalumination product of McjAlC CH, (Me2Al)3CMe, can lose Me3Al leading to a sublimable compound with the composition Me5AlgC4Me4 and an adamantane-like structure ... 

Despite the greater thermal stability of the four-membered alkyl substituted cyclodisil-thianes, the cage compounds (RSi)4S6 are thought to possess the adamantane-like structure. The methyl derivative has such a structure (Si-S bond lengths 212.9 pm), Jike the germanium and tin derivatives36. 

If Mn(0104)2 is reacted with 1 in alkaline solution in the presence of air, a black precipitate of the oligomeric oxo-bridged species, [Mn4(L)206] (0104)4, forms. This unusual (Mn(IV) species has been assigned an adamantane-like structure. 

The reaction between GeBr4 and H2S in CS2 gives Ge4SeBr4 with the adamantane-like structure (16), similar to the isoelectronic P4O10. 

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