Cubane 1,2-substituted bonds

One bond in substituted cubanes was cleaved oxidatively by thionyl chloride to yield polycyclic derivatives of dichlorocyclohexanes in 86-92% yield.147... 

Thallium(I) ethoxide has been known for many years, and a series of related alkoxides can be prepared by methods which include Tl + ROH, TIOH + ROH and T120 + ROH.295 The ethoxide,296 and a number of other TIOR compounds,297 are tetrameric in solution, and an X-ray crystallographic study of (T10Me)4 shows that the structure is based on that of cubane,298 with no T1—T1 bonding interactions. The bonding in such molecules has been discussed.299 Phenoxide, and substituted phenoxides, can be prepared from PhOH + TlOH, while reaction... 

The most stable turned out to be the derivatives ofcarbinols (CF3)nHmMe3HMnCOH and fluorinated phenols. They are described for Li, Na, and Ba and are formed on interaction of metals, hydrides, or alkyls, MR , with alcohols. The cubane-shaped NaORp molecules of this kind are present not only in the solid state but even in gas. The temperatures of their sublimation decrease on substitution for Me and H with CF3-groups. The stability of the Na...F bonds is so high that the gas-phase decomposition of these compounds ( 300°C) yields NaF [1386]. The observed frequency corresponding to the vibration of the C-O bonds in... 

The last example is the acidity of the ethynyl-expanded cubane 3. Inspired by the synthesis of the methoxy-substituted buta-l,3-diynediyl expanded cubane 4, Bachrach examined some of the properties of its smaller homolog 3. Since the s-character of the C-H bonds of 3 should be large and its conjugate base 3cb can potentially delocalize the anion into three neighboring alkynyl units, 3 might be quite acidic. 

Reactions with carbomethoxy-substituted cubanes (23, R = COOR) were also examined. The reaction of 23 followed by triphenylphosphine addition 5delded the corresponding ketones resulting from insertion into bond-type a and bond-type b in 66% and 34% selectivity, respectively. This selectivity, moreover, parallels that for the catalytic process using... 

A series of heterobinuclear Ti/Ru complexes are obtained from the initial treatment of Cp2Ti(SH)2 with [Cp RuCl]2 and subsequent reactions with excess of triethylamine, [Cp2Fe][PF6], excess of HC1, and boiling 1,2-dichloroethane. Some cubane-type sulfido clusters are obtained. X-ray diffraction studies and extended Hlickel molecular orbital calculations are carried out suggesting the existence of Ru —> Ti dative bonds and weak Ti Ti interactions. Substitution of one of the Cp rings by a chloro ligand in boiling 1,2-dichloroethane is also observed (Scheme 708).1781... 

The transmetallation of [Sn()a3-PSi Bu3)]4 74 with barium metal produces the cubanes 76-78 (Scheme 2.2.17) in which one, two, or three tin atoms are replaced by barium, cf, the mixed Sn-Pb clusters 50-52." " The cubanes 76-78 are also accessible from the reaction of a mixture of Sn[N(SiMe3)2]2 and Ba[N(SiMe3)2]2 with H2PSi Bu3. The substitution of tin by barium in these clusters results in a very large high-field shift of the RP ligand bonded to three tin atoms (8 P = -529)." Another cluster type... 

Syntheses have been made of energetically substituted cubanes. For example, 1,3,5,7-tetranitrocubane [10] (shown in Fig. 26) has been synthesized. As noted previously, its density is 1.814 g/cc. Another is the flu-dinitroethy] ester of tetracarboxycubane [36] (Fig. 27). The density is 1.762 g/cc. An energetic ammonium perchlorate substitution of cubone has been made in the form of 1,4-bis-cubanediammonium perchlorate hydrate [40] (Fig. 28). The dashed lines in Fig. 28 represent some of the many hydrogen bonds that occur in the crystal whose density is 1.7S5 g/ce. An estimate of the dry density extrapolated from this work is 1.83 g/cc- It was obtained by subtracting the volume and mass of water from the unit cell contents. The volume of H2O was taken to be the same as that in liquid water. 

Another approach is to study compounds based on derivatives of bicyclo-[2.2.2]octane and cubane. The carbon atoms labeled 1 and 4 are essentially the same distance apart in the two parent compounds ( 0.01 A). There are three different three-bond paths connecting Cl and C4 in bicyclo[2.2.2]-octane, but there are six analogous three-bond paths in cubane. A series of 4-substituted cubanecarboxylic acids (92) and 4-substituted bicyclo[2.2.2]-octane-l-carboxylic acids (93) showed similar effects of a substituent X on the pfCa of each parent compoimd. 

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