Tetraruthenium carbonyl clusters

Since the late 1990s, new approaches to the dispersion of noble metal particles in polymer matrixes by means of chemical, photochemical and radiation-chemical reduction, the evaporation of metal atoms (including solvated ones) into different supports, etc. have been developed (see Section 8-1) [44]. Nevertheless, catalysts prepared from individual immobilized metal clusters have more definite, mostly predetermined, structures. For these purposes derivatives of Oss, It4, RU4, Rh4, Rh6, etc. clusters are most often used. Earlier studies [46] showed that the rate of ethylene hydrogenation promoted by tetrairidium or tetraruthenium carbonyl clusters bound to phosphynated polymers decreased with an increase of the number of donor... 

The r/oro-octahedral RU4C2 unit found in [Ru4( 4-7 7/ 7 7 -C2RR )(CO)i2] (hereafter [Ru4( 4-2 2 -C2RR )(CO)i2] compounds) is frequently encountered in tetraruthenium carbonyl cluster chemistry and several... 

Linear and cyclic diolefins form a variety of clusters with trirutheniumdodeca-carbonyl or the tetraruthenium carbonyl hydrides. These belong to the compound types H2Ru3(CO)9L [56] or HRu3(C0)gl/ [55]. Type [56] complexes are obtained from cyclopentadienes (27 7), cyclooctadienes (74), or bicyclooctadiene (146). 

The vacuum pyrolysis of [Ru3(CO)12] with PhSeSePh at 185°C affords the tetraruthenium cluster [Ru4(CO)n(/i,4-Se)2] (86) (Fig. 28) as the only isolable product.75 By contrast, the reaction of [Os3(CO)10(NCMe)2] with PhSeSePh under mild conditions produces [Os3(SePh)2(CO),0] (87). Apparently, only the Se-Se bond of PhSeSePh is cleaved in this process.7677 In the reaction with the kinetically more labile [Ru3(CO),2] (compared with [Os3(CO)i2]) and with the use of more-forcing pyrolysis conditions, the Se-Se and Se-C bonds rupture and fragmentation of the carbonyl cluster takes place. Isolation of 86 as the major component suggests that this may... 

---