Adamantane-type structure

The phosphorus oxides, imides, their derivatives and their analogs usually have the adamantane-type structure shown in scheme 1. 

The compound CaHaBeMee is not a mdo-carborane, but has an adamantane-type structure 30a, 170a). 

Identical considerations suggest that the stabilities of the three isomers of CSB7H11 will decrease in the order XIII- > XIV- > XV-NlO. So also the C4BeHxo isomers should be less stable in the order XVII- 20, 165), XVTII-, XIX-NIO 14). Brown et al. 14a), at the University of Liverpool, have shown unequivocally that H4C4B0(CH3)e has an adamantane-type structure with sp boron rather than the carborane structure with sp boron. 

Advances in the Chemistry of Organic Ring Systems with Adamantane Type Structures ... 

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 reactions between (HsSOaE (E = S or Se) and H2SiCl2 or HSiCls (Scheme 47) afford an interesting series of compounds containing several Si to chalcogen bonds such as (HSi)4S6 (14), which was found to have an adamantane-type structure. ... 

Some carboranes have formulae compatible with both classically bonded and nonclassically bonded structures and exhibit valence isomerism. The tet-racarbaborane Me4C4B6Et6 is one such. As prepared by dimerization of the small closo carborane Me2C2B3Et3 [Eq. (3.2)], it has a classical adamantane-type structure, with its four CMe units linked through BEt units (1). However, when heated it isomerizes to the expected nido carborane structure (2) with a skeletal structure like that of decaborane. ... 

The condensed cage compound P4(PPh)g, forms a phosphorus pentoxide-type (adamantane-type) structure (Table 4.12). It can be made in high yields by reaction (6.714) which is carried out at -80 C in ether in the absence of air. The product is a yellow solid, very soluble in benzene, tetrahydrofu-ran, dioxane and so on, but insoluble in water and n-hexane. It is not oxidised in dry air but above 60°C it softens and converts to higher polymeric materials. The oxy derivative, P4(PPh)504, is made by a reaction similar to (6.714) using POCI3 instead of PCI3. 

The compound 2,8,9 trioxa-l-phosphaadamantane, mp=207°C, has a phosphorus pentoxide (adamantane)-type structure, and can be obtained by reacting -cis 1,3,5 cyclohexane triol with PCI3 or P(OMe)3 under completely anhydrous conditions. The corresponding oxide is obtained with POCI3 and an ozonide is known (6.980) [127]. Trimethyl phosphite reacts with another cyclohexane derivative to give a double-cage compound in low yield (6.981). 

The isopropyl derivative P4(NPr )e can have an alternative cage structure (7.289). On further heating this reverts to the more stable adamantane-type structure (7.287) [24]. 

The phosphido complex anion (Ph2P)4Cd( J,PPh2)6 has a P4O10 (adamantane)-type structure (Table 4.14) which can be compared with the similar (PhS)4Cd(SPh)g. 

HGXdlTIGthylenetetraiTline. Hexa, a complex molecule with an adamantane-type structure, is prepared from formaldehyde and ammonia, and can be considered a latent som-ce of formaldehyde. When used either as a catalyst or as a curative, hexa contributes formaldehyde-residue-type imits as well as benzylamines. Hexa [100-97-0] is an infusible powder that decomposes and sublimes above 275°C. It is highly soluble in water, up to ca 45 wt% with a small negative temperature solubility coefficient. The aqueous solutions are mildly alkaline at pH 8-8.5 and reasonably stable to reverse hydrolysis. 

---