Osmium complexes, fragments

Fe-Heterocycles and iron complexes with heterocyclic ligands 93 JOM(457)63. Ruthenium and osmium complexes with heterocyclic ligands, clusters including Ru- and Os-heterocyclic fragments 93JOM(457)121. 

In contrast to the reaction with phenylacetylene, the treatment of 190 with 2 equiv of methyl propiolate leads to the alkenyl-alkynyl compound 200 (Scheme 55). The use of a 1 1 molar ratio of alkyne to osmium complex gives the same product along with unreacted dihydride-dihydrogen complex [79]. The addition of a toluene solution of HCl to a toluene solution of 200 produces the carbon-carbon coupling of the alkynyl and alkenyl fragments to give selectively the... 

Aspects of this area have been reviewed by Creutz/ A number of new binuclear ruthenium and osmium complexes which can exist in mixed-valence form have been reported/ " The ligand 2,2, 3,3 -tetra-2-pyridyl-6,6 -biquinoxaline allows attachment of up to four Ru(II)(bipy)2 fragments. The molecule appears to act as two independent subunits which can exist in mixed-valence forms. Intervalence transfer (IT) bands detected for these mixed-valence subunits allow calculation of an electron transfer rate of 1 X 10 s" between the metal centers 6.8 A apart. 

The X-ray structure determination of 107 reveals that the osmium-carbon bond length is increased by 0.07 A on going from the parent carbyne complex 79 to the silver adduct 107. This may be contrasted with the weaker interaction between the metal-carbon bond and the Aul fragment in Os(CH2AuI)Cl(NO)(PPh3)2 (see Section IV,C,1). 

Autoxidadon of Bare ruthenium( II) and osmium(II) porphyrins - A resonance Raman study of the intermediates formed during the reaction of Ru(TPP) (which was obtained according Scheme 1, paths — f, — j, — k) in toluene [258] proved the anticipated [205] reaction scheme of the inner-sphere autoxidation, the first step of which is the formation of a p-peroxobis[porphyrinato-ruthenium(III)] complex which is split into two oxoruthenium (IV) fragments. These species precede the formation of /r-oxobisruthenium(IV) porphyrins (reaction 16) for P = TPP, OEP for P = TMP, a disproportionation (17) is indicated, the resulting Ru(P) itself is further autoxidized. 

The addition of a phosphine group to the organic fragment has been studied in some detail in compounds with cluster-bound vinyl ligands. The zwitterionic adducts which are formed can then undergo nucleophilic addition reactions (411, 461, 462). A reaction of this type also occurs with amine-substituted alkynes coordinated to osmium and ruthenium complexes (117). 

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