Cluster heptanuclear

In the families of heptanuclear clusters, two geometries are found the capped octahedron that is typical for 98-valence electrons, and the vertex-sharing open tetrahedral (butterfly) stmctures typical for 106-valence electrons. An example of the former is Osy(CO)22 (51) an example of the latter is [H2AuOsg(CO)2Q] (52). In the AuOs cluster anion, the gold atom is at the vertex-sharing position. 

Heptanuclear Trigonal Prismatic Clusters Stabilized by Monodentate Imidazole Ligand... 

The versatile binding modes of the Cu2+ ion with coordination number from four to six due to Jahn-Teller distortion is one of the important reasons for the diverse structures of the Cu-Ln amino acid complexes. In contrast, other transition metal ions prefer the octahedral mode. For the divalent ions Co2+, Ni2+, and Zn2+, only two distinct structures were observed one is a heptanuclear octahedral [LnM6] cluster compound, and the other is also heptanuclear but with a trigonal-prismatic structure. 

Scheme 4 Formation of the heptanuclear trigonal prismatic clusters 17-22...

Fig. 18 Heptanuclear trigonal prismatic clusters with amino acids as ligands...

Fig. 19 Possible structure of the mother species I,nNifi(gly)fi(p3 0n)3(n20)fi( j.2 OH2 )3 ]61 an

HEXACYANOMETALLATES AS TEMPLATES FOR DISCRETE PENTANUCLEAR AND HEPTANUCLEAR BIMETALLIC CLUSTERS... 

Heptanuclear clusters with Au-Fe [160, 306, 370-373, 394], Au-Ru [264, 319, 328, 374—390] and Au-Os bonds [327, 391-393] have also been reported. Most common structures are based on C-centered [160, 306, 374, 375] or B-centered [376-379] octahedral frameworks with a trigonal metal face capped by a gold atom, for example, in the anion of [NEt4][ (Me3P)Au MoFe5( j.6-C)(CO)17] 147 (Figure 4.39a) [160]... 

In the penta-, hexa-, and heptanuclear carbonyl hydride clusters, terminal hydrides are observed only in the less crowded species, and again no evidence for the presence of interstitial hydride is found. 

Fig. 7. Schematic representation of the molecular structures of the heptanuclear clusters.

Thermal reactions of a milder nature may also be employed. The use of partially substituted starting materials provides a means to enlarge medium size clusters. Thus, Os(CO)4H2 reacts to displace CH3CN ligands from Os6(CO)18- (MeCN) species to give heptanuclear clusters, Os7(CO) H2 ( = 20, 21, and 22). 

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