Octanuclear complex

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

There are two types of octanuclear complexes one with a core structure [Mng(//3-0)4-(/U4-0)2(//2-Cl)(//4-Cl)(/u- 7, 7 -carboxylato)7] and others which are aggregates of the planar or butterfly tetranuclear complexes mentioned above connected by bidentate ligands, such as pic,29i,308 bpg 292 bmpc (Figures 2 and 17). ... 

In the presence of excess AgNOs, 5 forms an octanuclear complex [(en)Pt(UH)Ag]4(N03)8 4H2O (11), which from its partially resolved X-ray structure has been assigned a pinched cone conformation where four Ag centers bind to the uracil 0(2) donor atoms of the four uracil monoanions. On addition of NaCl, all four Ag dissociate to give 6. 

The nitrate salt of the analogous [ (en)PtnAg(UrH, A (7),A (5),(9(2), 0(4)) 4]8+ cation exhibits a different structure, which can be formally derived from that of the pinched-cone conformer of Fig. 15,a, by coordination of silver ions to the uracilate oxygens. In all the octanuclear complexes, two metal units, Pt(en) and M, represent each corner of the boxes. These results demonstrate that, irrespective of the 120° angle between the Pt-N(l)... 

Thus the conclusion is that tetranuclear complexes are likely to be the active species in the reduction of N2 to hydrazido derivatives, and then to hydrazine, by reaction with solvent in protic media, whereas octanuclear complexes (or transition states) are needed to transform N2 species into two ammonia molecules. 

Reactions of Cp 2Ti(Me3SiC2SiMe3) (Cp = Cp, Cp ) with triazine afford binuclear chelate complexes. Reactions with pyrazine display varied behavior and trinuclear and tetranuclear complexes are formed. The reaction with pyrimidine gives octanuclear complexes. C-C coupling reactions are observed in these reactions. Some molecular structures of these products have been determined by X-ray diffraction (Scheme 582).1514... 

Very recently, a new structural type has been found that involves an eight-membered Pt4(OH)4 cycle stabilized by coordinatirai of each platinum(ll) center to two silver(T) ions (Scheme HE) [28], The octanuclear complex [ft(C6Cl5)2(li-OH) (p-Ag)]4 is formed by reacting the dinuclear complex [ft(C6Cl5)2(p.-OH)]2 ... 

Strontium, cadmium, and hafnium are present in the remarkable trimetallic octanuclear complex [Sr2Cd2Hf4(OPr )24] (Fig. 4.61). °° This centrosymmetric molecule has... 

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