Cubane, methyl

Figure 10-8 Sequential (tlypothcticaP nydrogcnation of Cubane to, T4-Di methyl hexane.

In the pursuit of new high-energy-density fuels, fuels with strained molecules have been developed and their combustion characteristics studied [1]. Fuels such as dihydrobenzvalene (CeHg) and methyl cubane ((C H7)CH3) are strained dur-... 

The strong preference for oxygen over carbon as a donor atom is shown by the rapid decomposition in water of most compounds with a covalent M—C bond or an ionic M+. .. C- interaction. The effect of the differences in electronegativity is shown in the structures of methyl lithium and methyl potassium. The methyl lithium tetramer, (39), has a cubane ... 

Wilier, R.L., and Stem, A.G. (1993) Manufacture of diethanolammonium methyl cubane nitrates for liquid gun propellants. US Patent 5,232,326 Chem. Abstr., (1994) 120 (8), 1953 . 

A different type of dynamic process involving a polynuclear metal system has been identified in [(CH C H,)ltRul)Sl(]2+, which has a distorted cubane-like structure with three Ru—Ru bonds in the crystalline state (Fig. 15.56). By following its methyl and ring proton resonances over a temperature range from +70 to —43 BC (Fig. 1537), the complex is shown to undergo a dynamic process involving the metal-metal bonds. At the low-temperature limit, the spectrum contains features predicted for the static structure two lines of equal intensity for the methyl protons... 

Cubylcarboxonium ions have been also studied by Prakash, Olah, and co-workers.579,580 The parent cation 281 prepared under superacid conditions was stable at low temperature but decomposed to cubylacylium cation 282 as a result of further protonation and dehydration [Eq. (3.71)]. In addition to cation 281, di- and tetra-carboxonium ions and the corresponding protonated methyl esters were also observed as long-lived species stable under superacidic conditions. Experimental evidence and theoretical data indicated that the strained cubyl system effectively stabilizes the carbocationic centers through C—C bond hyperconjugation (283). On the basis of 13C data, three conformers of protonated dimethyl cubane-l,4-dicarboxylate (284-286) could be identified. 

Methyl-3-heptanol, stereoselective preparation, 9, 12 Methylidyne cubane, via Ti(IV) complexes, 4, 407 <7-Methyl-(tj5-indenyl)chromium tricarbonyl, rearrangement,... 

Non-activated methyl groups are never attacked in these reactions toluene can be functionalized but isolation of the resulting benzyl halides from these PTC mixtures is difficult. Most remarkable is that strained hydrocarbons such as cubane (5) or 2,4-didehydroadamantane (6) can also be halogenated with conservation of the cage [27], in marked contrast with the halogenation reactions of these substrates with halogen radicals [40]. Dihalogenations with either the same or a differ-... 

Fig. 5. Methyl 3,4-difluorocubane-l-carboxylate difference density maps in various diagonal planes of the cubane cage. The maxima of the bond densities lie outside, implying that the cage bonds are bent (reproduced with permission from Imgartinger et al. [45]).

Recently the ultrafast radical-clock technique (kr = 5xl012 -1013 s 1) has been developed (Newcomb et al, 2000 and references therein). Two probes, trans, trans-2-methoxy-3-phenylmethyl cyclopropane and methyl cubane were used to study the... 

There is spectroscopic evidence for nickel-methyl complexes in CODH of anaerobic bacteria. Here the nickel center is linked to an Fe4S4 cubane cluster it is this, not Ni, which appears to act as the binding site for CO. In a subsequent step the methyl ligand is then transferred from Ni to the coordinated CO to generate the acetyl function of acetyl coenzyme A.28... 

L = PMes) to allow the use of rare, gaseous and solid alkanes. These studies show that methane gives the methyl hydride, cubane the cubyl hydride (without C—C bond breaking) and adamantane the secondary adamiuityl hydride. 

Cuban l-Carboxy-4-methyl- El7e, 324 (2-Br —keton-Ringvereng.) Cyclooctatetraen Methoxycarbonyl-IV/5a, 500 E17c, 2201 (7-COOR — bicyclo[4.2.0]ocia — 2,4,7-trien/hv)... 

Interestingly, there is one substrate that is predicted by molecular mechanics calculations to ionize still more slowly than 38. This compound is 39, a derivative of the hydrocarbon known as cubane, and in which the CCC bond angles are 90°. However, in contrast to 36, and especially 38, the ester 39 undergoes SN1 reaction in methanol much faster than expected. The product from 39 is the corresponding methyl ether 40 (see Eaton9). 

The structure of the Co4 molecule is shown in Fig. 10. The four Co and four oxygens from four hydroxy methyl pyridine ligands form a cubane like central C04O4 structure. The molecule has S4 symmetry. Our NRLMOL calculations confirmed the ferromagnetic ordering indicated by experiment. However, the magnetic anisotropy barrier was found to be 23 K. In the... 

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