Octanuclear

The anodic scans of the three related octanuclear anionic clusters Re7Pd(/4(,-... 

We also mention the octanuclear chromic wheels [CrF(02CCMe3)2]8 (41) and [Cr8(0H)8(02CPh)i6] (42), which contain eight Cr(III) ions anti-ferromagnetically coupled. 

Fig. 17. Ball and stick representations of the octanuclear rings (a) [Mo80i6(0CH3)8 (C204)]2-, (b) [Mo8S6016(OH)3(C204)]2 , (c) [V808(0CH.s)lti(C204)l2 (d) their common polyhedral representation.

Octanuclear molybdenum wheels incorporating a Mo(VI) (94) or a W(VI) (93) octahedron can also be prepared from a basic solution of the oxothio precursor containing a stoichiometric amount of molybdate or... 

Figure 25 Formation of an octanuclear ZrIV— Pd11 complex.

Figure 49 Cyclic sulfur-bridged octanuclear complexes [M2 Pd[Co(aet)3]2 2] ...

Several octanuclear gold cluster have been characterized and are of the type [Au8(PPh3)8]2+,3233,3234 [Au8(PPh3)7]2+,3235 or [Au8(PMes3)6]2+.2714 The structural skeletons for these compounds are different and are shown in Figure 29. 

Trinuclear zinc carboxylate structures of the form MZn2(MeCH=CHC02)6(quinoline)2 have been structurally characterized with M = Mn, Co, Ni, Zn, Cd, Mg, Ca, Sr. Structural variation is observed for the group 2 metals. The remaining complexes all show linear trimers with the central metal atom octahedrally coordinated and linked to each zinc by two bidentate and one mono-dentate carboxylate.377 A basic benzoate octanuclear structure with four vanadium(III) and four zinc atoms has been characterized, [VZnO(benzoate)3(TF[F)]4-2TnF.378... 

The arrangement of zinc and sulfur atoms in the Zn4S core is similar to the observed Zn40. Theoretical calculations demonstrated that the compound is a poor model of extended metal chalcogenide semiconductors (ZnS). Octanuclear zinc compounds have also been structurally characterized with this core. In the presence of an alkylammonium cation, a sulfide containing octanuclear zinc species was formed [BzEt3N]2[Zng(S)(SBz)i6].126 The complexes with benzylthiolate... 

In compliance with the nuclearity principle, polynuclear clusters are subdivided into a number of other subgroups, e.g. hexanuclear, octanuclear, etc. The binuclear clusters of technetium may be classified according to the electronic structure of their Tc-Tc2 bonds. Then, the d4-d4 complexes with quadruple M-M bonds are the father of all binuclear complexes with Tc-Tc bonds. The addition or removal of electrons from Tc-Tc bonds [1,11] should result in a decrease in the formal multiplicity of M-M bonds. Thus, for instance, the formal multiplicity of Tc-Tc bonds of d3-d3 and d5-d5 binuclear complexes equals3 3, that of d4 d5 and d4-d3 complexes equals 3.5, etc. 

Compounds (I), (II), (III), and (IV) (Table 2) have similar crystal and molecular structures (Fig. le), characterized by the following the crystals of these compounds are made of octanuclear cluster fragments [Tc8Br4(/(-Br8]"+... 

In compounds (II) and (III) (Table 2) a very short O-O distance is observed, which is due to the formation of strong hydrogen bonds in [H(H20)2] + cations, whereas in compound (I) the 0-0 distance is about 0.3 A longer (Table 1 and papers [44,73,74,101]). In compounds (I) and (II) in contrast to (III), the Brax atoms are simultaneously bonded by way of an electrostatic interaction with two octanuclear fragments, thus forming in the crystals of these compounds endless chains. 

Based on its method of synthesis and some of its spectroscopic properties, compound (X) belongs to the group of octanuclear clusters (I)—(IV). However, its exact structure is still undefined. According to most of its physico-chemical properties, compound (X) is similar to [Fe(C5H5)2]3 [Tc6(/j-C1)6C16]C12 and... 

B. Redox Disproportionation of Mixed-Valence Tetranuclear and Octanuclear Compounds... 

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