Hydride complexes trinuclear

Other noteworthy trinuclear hydride complexes include HMn3(CO)10(BH3)2 121>, a rare cluster containing both M-H-M and M-H-B bridges (Fig. 25), and the com-... 

Following the development of group 2 complexes for the controlled polymerization of styrene, in 2006 Harder and coworkers reported the hydrosilylation of a series of activated alkenes with Ph SiH4 (n = 2 or 3) catalyzed by [ (Me2N-o-C6H4) CHSiMes 2M(THF)2] (M = Ca, Sr) and isolated the first calcium-hydride complex [ (ArNCMe)2CH Ca p-H)(THF)]2, a species relevant to the catalytic reaction [116, 117], In related studies, Okuda and coworkers have isolated a cationic trinuclear calcium hydride cluster and demonstrated its competency for the hydrosilylation of styrene with phenylsilane (Fig. 10) [118]. 

Reactions of hydrides are therefore similar to those of carbonyls, and by appropriate choice of reactants a product often can be made by either route, as is shown for the mercuration of trinuclear Ru complexes ... 

The tetranuclear and trinuclear clusters will only be observed at low pressures [8], but all other species are very common under hydroformylation conditions. Complex 4 is an ionic complex that is formed in polar solvents [9] and even hexa-solvated, divalent cobalt species may form as the cation. Under practical conditions both the dimers and the hydrides are observed, thus depending on the hydrogen pressure there will be more or less of the hydride present. 

The mechanisms of these reactions are probably complex but radical processes seem likely. The final products of insertion into the metal metal bond are actually trinuclear species. Insertion into terminal metal hydride or metal alkyl bonds could, in principle, generate mixed-metal dimers. In practice, aside from insertion into the metal halogen bond, such as that shown in equation (65), few such reactions have been reported. 

Known carbonyl hydrides of mthenium include the unstable HRu(CO)4, as well as the trinuclear H2Ru3(CO)n, tetranuclear H2Ru4(CO)i3 and H4Ru4(CO)i2, and complexes of even higher nuclearity, as well as substitution and deprotonation derivatives. A special feature of mthenium carbonyl chemistry is the existence of series of carbonyl... 

The trinuclear pentahydride complex [Cp Ru]3(/w-H)3(/x3-H)2 (105) in Scheme 26 consists of ruthenium centers tightly bound by bridging hydrides. Treatment of the pentahydride complex with excess butadiene in THF results in a trinuclear 1-methyl-1,3-dimetalloallyl complex [Cp"Ru]3(H)4[/x3- ] -C(Me)CHCH] (106). This interaction shows the cooperation of all three ruthenium centers as either coordination sites or activation sites. Similar results are found by treating (105) with isoprene. Treatment of (105) with five equivalents of cyclopentadiene results in bond cleavage of the cyclopentadiene to form a dark purple crystalline solid [Cp Ru(/u.-H)]3[/x3- j4-C(Me)=CHCH=CH] (107). In this complex, two of the ruthenium centers act as a coordination site, while the third is an activation... 

---