Tetranuclear mixed-metal

For some reviews, see (a) Majoral J-P (2007) Influence of cationic phosphorus dendrimers on the surfactant-induced synthesis of mesostructured nanoporous silica. New J Chem 31 1259-1263 (b) Puntoriero F, Nastasi F, Cavazzini M et al (2007) Coupling synthetic antenna and electron donor species a tetranuclear mixed-metal Os(II)-Ru(II) dendrimer containing six phenothiazine donor subunits at the periphery. Coord Chem Rev... 

Taking advantage of both aurophilicity and argentophilicity, tetranuclear mixed-metal complexes which contain pairs of Au and Ag atoms have been prepared, as shown in Fig. 19.6.3. In the preparation of mixed gold/silver polynuclear complexes, aurophilicity and argentophilicity have been utilized to promote cluster formation. Figure 19.6.4 shows the cores of several mixed gold-silver clusters. 

H. Stoeckli-Evans, M. Hemy, G. Laurenczy, R. Roulet, Amphiphilic organoruthenium oxomolybdenum and oxovanadium clusters. Polyhedron 17 2817 (1998) c) L. Plasseraud, H. Stoechli-Evans, G. Siiss-Fink, [(Ti6-p-Pr C6H4Me)2Ru2Mo206(OMe)4]-A new tetranuclear mixed-metal 0x0 cluster presenting a cube-based chair structure, Inorg. Chem. Commun. 2 44 (1999). 

The mixed-metal tetranuclear derivatives that have been prepared are H2Re2Ru2(CO)i6, CReRu3(CO)16] , HMnOs3(CO)16, and HReOs3(CO)18 (238). All the complexes result from the reaction of the carbonyl, M3(CO)i2, with the related anion, [Mn(CO)5]- or [Re(CO)s]. The ruthenium anion [ReRu3(CO)16] was isolated as its tetramethylammo-nium salt. The infrared spectrum was complex, but consistent with... 

In mixed metal clusters, redistributions can occur in the mass spectrometer so that the highest observed peak arises from such a product. This is clearly exemplified by the heterometallic dodecacarbonyls containing metals of the cobalt triad. The thermal stability of this series of clusters decreases as the rhodium content increases and facile redistributions result in the formation of tetranuclear species containing less rhodium the very thermally stable Q I CO) does not rearrange184. ... 

The First Effective Light-Harvesting Antenna The Mixed Metal Os-Ru Tetranuclear Dendrimer... 

As the energy of the excited states and the redox levels of each metal-polypyridine unit depend on metal and ligands in a predictable way, the simultaneous presence of different metals in a dendritic structures gives rise to intramolecular energy transfer processes as well to different redox patterns with multielectron processes. In particular, the tetranuclear [Os(2,3-dpp)3 (2,3-dpp)Ru(bpy)2 3]8+ (OsRu3) shown in Fig. 5.3 has been designed to achieve an efficient antenna effect. This species can also be considered a first-generation mixed-metal dendrimers.31... 

D. PLANAR TETRANUCLEAR CLUSTERS WITH MIXED-METAL CORES, MiMo2(Ti5-C5H5)2(CO)6(PPh3)2 M =Pd or Pt... 

Bi- and tetranuclear, three-center two-electron gold(I) complexes have been prepared containing polyfluorophenyl groups (129). The binuclear complexes are of the type discussed previously, [Ar(AuL)2]X and [Ar Au2(dpe) ]BF4, whereas the diarylaurates reacted to give tetranuclear compounds [Eq. (35)] suggested to be of the same type as the mixed metal complexes discussed above. 

Table I. Fragmentation of Mixed-Metal Tetranuclear Clusters with Carbon Monoxide at 1 Atmosphere Pressure (17)...

Most of the reported reactions between tetranuclear clusters and alkynes involve mixed-metal cluster species. In these systems hydride and carbon monoxide substitution generally occurs [Eq. (11)] (194-200), although in some cases Me3NO has been used to activate the starting material (201, 202), and in still others cluster breakdown takes place even under mild reaction conditions (203). Rh4(CO)12 (204) and Ir4(CO)12 (205) retain their nuclearity in reactions with alkynes, but in the latter case the metal framework geometry is altered (Fig. 7). The use of [Ir4(CO)11Br] instead of Ir4(CO)12 in reactions with alkenes produces alkene-substituted tetranuclear complexes (189), as shown in Fig. 7. Few other homonuclear clusters have been found to react with alkynes (206-208). In the reaction between the tetranuclear cluster Cp2W2Ir2(CO) 0 and diphenylacetylene two independent processes... 

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