Triosmium complexes examples

In organometallic clusters, ligands frequently appear to move over the surface uf the metal framework. The triosmium complex. Os,(CO)10(mj-tj -CH3CH2C C-CH2CHj), in Fig. 15.54 provides an example in which the alkyne moves over the... 

The triosmium complex Os3(CO)9(/i-H)(jU3- j -Ci2H6) is accessible from the reaction between acenaphthylene and Os3(CO)io(NCMe)2. Further treatment with acenaphthylene at 160 °C leads to identification of four products, including two dinuclear species, 525 and 526, both of which share structural similarities with 523. A further analogous example is 527 (R = C=CFc), obtained from the reaction between (FcC Z )2 and Os3(CO)io(NGMe)2. ... 

Examples of O-alkylation have also been demonstrated for triruthenium and triosmium anionic clusters, as well as the tetrairon cluster Fe CO)] - (31-33). This reaction has considerable promise as an entry into many different methylidyne complexes through the replacement of the OR" group, eq. 20 (38). 

The relatively stable polymetallic Os3(CO)i2 (ref. 6) may be activated by conversion to anionic derivatives. Reduction of Os3(CO)j2 with potassium benzophenone gives the reactive, air-sensitive triosmium dianion [Osj(CO)i, ] . Generally, it is convenient to generate and use this complex immediately, without isolation Section B describes an example of this procedure... 

Coordination-dehydration reactions of propargyl alcohols have been followed in detail on triosmium clusters an example is given in Fig. 26.1 Protonation of triosmium clusters substituted with parallel alkynes leads to propargyl cationic derivatives which, in turn, can isomerize to allenylidene complexes. Fig. 27.1 ... 

The ability of sol-gel entrapped compounds to catalyze reactions that do not take place by the non-entrapped materials is even more pronounced when an alumina sol-gel matrix is used. For example, while dihydrogen treated of triosmium- and triruthenium dodecacarbonyls [i.e., H40s4(C0)i2 andH4Ru4(CO)i2] are poor hydrogenation catalysts (see e.g., Ma, 1990) their immobilized versions in alumina sol-gel are highly active catalysts for the reduction ofalkenes and nitro groups at 60°C under 20-25 atm, H2 (Schemes 24-27 and 24-28). The alumina sol-gel entrapped ruthenium carbonyl complex even catalyzes... 

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