Ru3

Reductive carbonylation of nitro compounds is catalyzed by various Pd catalysts. Phenyl isocyanate (93) is produced by the PdCl2-catalyzed reductive carbonylation (deoxygenation) of nitrobenzene with CO, probably via nitrene formation. Extensive studies have been carried out to develop the phosgene-free commercial process for phenyl isocyanate production from nitroben-zene[76]. Effects of various additives such as phenanthroline have been stu-died[77-79]. The co-catalysts of montmorillonite-bipyridylpalladium acetate and Ru3(CO) 2 are used for the reductive carbonylation oLnitroarenes[80,81]. Extensive studies on the reaction in alcohol to form the A -phenylurethane 94 have also been carried out[82-87]. Reaction of nitrobenzene with CO in the presence of aniline affords diphenylurea (95)[88]. 

Synthesis. The most important starting material for the synthesis of mthenium compounds is the commercial trichloride ttihydrate. Other useful starting materials include [RuCl3(OH2)]2- [3187-84-2], [Ru30(00CCH3)3(0H2)3]00CCH3 [38998-79-7], and [Ru3(CO) 2] [15243-33-1]. 

Ru3(CO)i2, CO, 20 atm, 4 h, 100°. These conditions reduce the oxime to an imine that is easily hydrolyzed with water. Aldehyde oximes give low yields of nitriles. 

Reaction of diphenyl-2-thienylphosphine with Ru3(CO)l2 gives the tiVp) ti Ti C) coordinated species, 144, along with cluster 145 where two ligand molecules participate in coordination, one via the phosphorus atom and the C=C bond of the heteroring, and the other via the phosphorus atom only. P-Coordination in the products of such an interaction is known [95JOM(488)85]. Complex 144, the main product, interacts with carbon monoxide to yield the P-coordinated cluster, 146,... 

Ring opening of the heteroring (C—S bond cleavage), 300, or even ring opening with elimination of the heteroatom, 301 and 302, happens in the reaction of benzothiophene with Ru3(CO)l2 (94AGE1381). 

Clusters Ru3(CO)l2 and Os3(CO)l2 as well as their substitution products, e.g. [Os3(CO)lo(AN)2], activate pyrrole and its derivatives in many different ways. Thus, dihydrides 43 (R = H, Me) follow from triosmium dodecacarbonyl and pyrrole or 1-methylpyrrole [82JCS(D)2563 84P1175 86JOM(311)371]. Complex 43 (R = H) isomerizes as a result of proton transfer to the more stable species 44 and... 

Mercaptobenzothiazole with [Ru3(CO)i2l gives the cluster 41 (76TMC186, C192, 78IC2103). Two ruthenium atoms are bonded to the exocyclic sulfur site, while the third one is coordinated via the nitrogen heteroatom. 

The ruthenium analogue of 47 Ru(ri5-C5Ph5)(CO)2Br (48) is also available, when Fe(CO)5 is replaced by Ru3(CO)12 [68]. A wide range of substitution products were obtained through replacement of both carbonyl and bromide ligand against two-electron ligands L such as phosphines, phosphites, and ethylene. Electrochemistry of these derivatives were studied in some detail. 

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