Rhodium with cyclopentadienyls

Recently. Alvarado et al. reported a related set of active catalysts for quinoline hydrogenation, formed in situ by addition of pyrazolylborate ligands Tp, hydrotris(pyrazolyl)borate and Tp. hydrotris(3,5-dimethylpyrazolyl)borate -which are isolectronic with cyclopentadienyl ligands- to [M(COD)C1]2 (M = Rh, Ir, COD = 1,5-cyclooctadiene), [Ir(COE)Cll2 (COE = cyclooctenc), and RuCl2(NCMe)4. Again, rhodium turned out to be the most efficient metal, and the activity was related with the ease of formation of Tp or Tp complexes. No mechanistic details were provided [101]. 

Some rhodium complexes such as 88,89, and 90 with cyclopentadienyl ligands bearing a dimethylaminoethyl side-... 

Reaction of the cyclopentadienyl rhodium and iridium tris(acetone) complexes with indole leads to the species 118 (M = Rh, Ir) [77JCS(D)1654 79JCS(D)1531]. None of these compounds deprotonates easily in acetone, but the iridium complex loses a proton in reaction with bases (Na2C03 in water, r-BuOK in acetone) to form the ri -indolyl complex 119. This reaction is easily reversed in the presence of small amounts of trifluoroacetic acid. 

The rhodium cyclopentadienyl complex [T75-C5(CH3)5RhCl2]2, in the presence of base at 50 atm H2, also effects stereoselective catalytic hydrogenation of benzenes. Substrates with unprotected —OH or —C02H groups were not effectively hydrogenated, but aryl ethers, esters, and ketones and N,iV -dimethylaniline were all reduced, some-... 

Cyclopentadienyl rhodium silyl derivatives include Cp Rh(H)2(SiEt3)2, which has been used as a precursor to heterometallic clusters.257 The photolysis of CpRh(PPh3)(7]2-C2H4) with SiHR3 (R = Et, Pr1) results in oxidative... 

C7H704Rh, Rhodium(I), dicarbonyl(2,4-pentanedionato)-, 34 128 C7HgN4, Bis(l-pyrazolyl)methane, bpm, complex with nickel(ll), 34 139 CgH5FeKN20, Ferrate(ll), carbonyldicyano-(cyclopentadienyl)-, potassium, 34 172 CgH23Ns, Tetraethylenepentamine, tetren, complex with nickel(ll), 34 147, 148 CgH24B2N4, Diborane(4), tetrakis(dimethyl-amino)-, 34 1... 

The cyclopentadienyl group, or its substituted derivatives, might be expected to stabilize dioxygen complexes or to ultimately react with dioxygen under the influence of transition metal centers. In rare cases, other (uncharged) dienes can also be found to stabilize dioxygen complexes of rhodium. Also discussed here are some reports of metallaben-zene systems and their reactions with dioxygen. 

Protonation of dienol complexes (53) with hexafluorophosphoric acid in diethyl ether affords air-stable salts (55) in high yield [Eq. (27)] (206). While the iron derivatives (21) are rapidly hydrolyzed, the cyclopentadienyl rhodium and iridium salts (55) are much less reactive (207). 

Cyclopentadienyl(triisopropylphosphane)vinylidenerhodium reacted with tellurium in benzene to give a green ethenetellurolato-rhodium complex1. 

Cyclopentadienyl cobalt and rhodium complexes with 1,2-benzenedithiolate or S2C2R2 type ligands readily add unsaturated carbon molecules to form tridentate ligands exhibiting S2C donor sets. When nitrenes are added, dithio-lene derived ligands with S2N donor sets result. Scheme 3 shows examples of... 

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