Cubane molecular structure

R. J. Butcher, A. Bashir-Hashemi, R. Gilardi, Network hydrogen bonding the crystal and molecular structure of cubane-l,35,7-tetracarboxylic acid dihydrate , J. Chem. Cryst., 1997, 27, 99-107. 

Figure 11.3 Molecular structure of the multicyclic compounds cubane, tetrahydrodicyclopenta-diene and adamantane...

Reactions of limited proportions of amine and phosphine Lewis bases with non-molecular copper and silver halides generate crystalline cubanes. Crystallographic determinations of molecular structure have been reported for at least 31 complexes with cf or d10 metal configurations, spanning the following types or homologous series of compounds. Compilations of data occur in references 157, 158 and 167. 

The iron-selenium cubane-type cluster [Fe4Se4(NO)4] has been shown (52) to adopt a molecular structure of almost exact Td symmetry, whereas in the corresponding anion [Fe4Se4(N0)4] the symmetry is lowered to D2a, just as for the sulfur analogs (37). Upon one-electron reduction the size of the Fe4 cage increases in the neutral molecule the Fe-Fe and Fe-Se distances are 2.703 and 2.342 A, but in the anion the... 

Fig. 2. Comparison of the molecular structures of the tellurium(IV) fluoride, chloride, and iodide types in the solid state. The selenium(IV) chlorides and bromides as well as tellurium(IV) bromide and one of the five forms of tellurium(lV) iodide are isostructural to the cubane-like Te4Cli6 molecules (244).

An obvious approach to render these rigid-rod polymers colorless is to synthetically alter their molecular structures so as to disrupt their conjugation systems. This modification is, of course, predicated on imposing little or no adverse effects on the other important properties of the polymers, for example, environmental survivability. Cage-like, aliphatic hydrocarbon molecules, such as adamantane, diamantane, cubane, etc., are thermally stable, and non-chromophoric due to the lack of 7t-electrons. Some of these cage molecules can be synthesized as difiinctionalized monomers that also satisfy the all-para molecular geometry requirement of rigid-rod macromolecules. 

Fig. 2. Schematic representation of the molecular structure of a cubane single-cluster Fd. The cluster ligands are labeled by both the conserved ligation sequence I-IV and the sequence position in /yFd, 11,14, 17 and 56, with position 14(11) occupied by Asp in WT P/Fd. The alternate oxidation states of the two Cys-21(V), Cys-48(VI) remote from the cluster, two free sulfhydtyl and a disulfide bond, are designated by the B and A form, respectively. [Reprinted from L. Calzolai, C. M. Gorst, K. L. Bren, Z.-H. Zhou, M. W. W. Adam, and G. N. La Mar, J. Am. Chem. Soc. 119,9341 (1997), with permission.]...

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