Isolated octahedral clusters

Isolated octahedral clusters are scarce. There appears to be only one example, Cs2Lu[ CLu6 Cli8], in which not only the CLue cluster is isolated but also the [ CLu jClig] cluster complex unconnected. The most prolific families with isolated clusters are the so-called 7-12 and 6 10 type compoimds, halides of the compositions ZR6 Xi2R and ZR jXio. These are mostly iodides for the 6-10 type, bromides are equally fi equent, perhaps a packing problem. ... 

Isolated octahedral M6(p3-Q)82+ (Q=S, Se) clusters are found in a big family of Tc and Re ternary sulfides and selenides of general formula AxM6Qn+ ) where A is an alkali, Tl+, Cu+ (x=4) alkaline earth, Eu2+ or Pb2+ (x=2) ion, and y = 0, 1 or 2. These phases were discovered and thoroughly studied by Prof. W. Bronger s group. The cluster units contain regular M6 octahedra with M-M bond lengths of 2.60-2.65 A for Tc and... 

The chemical reduction of the higher Mo and W halides provides good yields of the octahedral clusters, but the mechanism is obscure. By contrast, chemical oxidation of zero-valent Mo and W leads to the bromo and iodo cluster species in poor yields but provides considerable insight into the formation of these cluster compounds. The reaction of the hexacarbonyls Mo(CO)6 or W(CO)6 with I2 at moderately low temperatures produces a mixture of metal halide phases (25, 16). In the reaction W(CO)6 with I2, lower nuclearity clusters have been isolated as reaction intermediates that lead to W6 species. The tri-, tetra-, and pentanuclear tungsten iodide species are obtained from W(CO)6 and I2 by varying reaction times and temperatures, and the... 

The previous structures, which contain distinct R octahedral clusters, necessarily have R/Z > 6. When R/Z > 4, we can find a finite number of these clusters condensed to give larger molecular units. For rare earth halide systems, only edge-sharing octahedra have been observed, as delineated in sect. 2, in which only two octahedra are involved and the interstitial moiety is a C2 dimer. Satpathy and Andersen (1985) applied the LMTO-ASA method to produce the energy DOS illustrated in fig. 43. Their model examined the interaction between an isolated GdioCljs cluster with two... 

Octahedral cluster iridiiam carbonyl derivatives have also been described (275), but these have been investigated in less detail than their cobalt or rhodium analogs. They are obtained by the alkali-metal reduction of Irit(C0)i2 in a manner somewhat similar to the preparation of octahedral cluster cobalt carbonyl derivatives by the alkali-metal reduction of Coit(C0)i2 Reaction of Irij(C0)i2 with sodium metal in tetrahydrofuTcin first gives the tetrahedral cluster anion Hirij (CX7) i" aind then the dark brown, octahedral cluster anion Ir0(CO)i5 , which can be isolated as its tetraethylammonixam salt (275). ... 

Only octahedral clusters TRs (= T,Rr with r/f=6.0) are known as being isolated in a sense that cluster atoms R are not shared with other clusters. 

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