Structural chemistry cubane structure

Trinuclear Cuboidal and Heterometallic Cubane-Type Iron-Sulfur Clusters New Structural and Reacticity Themes in Chemistry and Biology R. H. Holm... 

In addition to analogs of known C-based structures, transition metals offer novel bonding possibilities having no known precedents in main-group chemistry. As a variation on the cubane-like cage motif of Fig. 4.26(c) built from tetravalent osmium, we can envision construction of the analogous naked metal cage compound Irg... 

A brief historical note on the structure of the iron-sulfur clusters in ferredoxins is relevant. After the first analytical results revealed the presence of (nearly) equimolar iron and acid-labile sulfur, it was clear that the metal center in ferredoxins did not resemble any previously characterized cofactor type. The early proposals for the Fe S center structure were based on a linear chain of iron atoms coordinated by bridging cysteines and inorganic sulfur (Blomstrom et al., 1964 Rabino-witz, 1971). While the later crystallographic analyses of HiPIP, PaFd, and model compounds (Herskovitz et al., 1972) demonstrated the cubane-type structure of the 4Fe 4S cluster, the original proposals have turned out to be somewhat prophetic. Linear chains of sulfide-linked irons are observed in 2Fe 2S ferredoxins and in the high-pH form of aconitase. Cysteines linked to several metal atoms are present in metallothionein. The chemistry of iron-sulfur clusters is rich and varied, and undoubtedly many other surprises await in the future. 

The formation of tetrameric aggregates with a hetero-cubane structure is a structural motif that is observed for several alkylzinc alkoxides in the solid state (Figure 80). In these structures the alkoxy group is -bonded with its oxygen atom to three zinc atoms. The structural elucidation of [MeZnOMe]4 (152) represented the first example of such a structural motif in organozinc alkoxide chemistry . Later, similar structures were observed for alkylzinc alkoxides containing other alkoxy groups (153, = f-... 

Abstract. Geometrical parameters, total energy, heat of formation, energies of HOMO and LUMO orbitals, density of one-electron states (DOS) are determined by using of semi-empirical quantum chemistry PM3-method for isolated molecules Cn, dimers (Cn)2 and cuban-like clusters (Cn)8 for n = 20, 24, 28, 32. The results of calculations allow assuming the existence of polymerized cubic crystal structure on base of all considered small fullerenes. 

Prismane is an example of another interesting strained compound. Because it contains three-membered rings fused with four-membered rings, it should be even more strained than cubane. Prismane was prepared in 1973. It is a liquid that is stable at room temperature but explosive under some conditions. In toluene at 90°C its half-life (the time it takes for one-half of the compound to decompose) is 11 h. Note that prismane is isomeric with benzene. In fact, it was one of the structures proposed for benzene in the early days of organic chemistry. 

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