75070-58-5Relevant academic research and scientific papers
Coupling of two ethyne molecules at rhodium versus coupling of two rhodium atoms at ethyne. 2. Implications for the reactivity. Catalytic and stoichiometric functionalization reactions of ethyne
Bianchini, Claudio,Meli, Andrea,Peruzzini, Maurizio,Vacca, Alberto,Vizza, Francesco
, p. 645 - 651 (2008/10/08)
The rhodacyclopentadiene complex [(triphos)RhCl(η2-C4H4)] (3) has been synthesized by treatment of [(triphos)RhCl(C2H4)] (1) in CH2Cl2 with an excess of ethyne (triphos = MeC(CH2PPh2)3). Complex 3 catalyzes under very mild conditions the cyclotrimerization of ethyne to benzene as well as the cyclocooligomerization of ethyne with acetonitrile to 2-picoline. A plausible catalysis cycle for both reactions is proposed on the basis of multiform experimental evidence. Complex 3 is a potential synthon for the preparation of a variety of heterocyclic compounds containing the C4H4 diene moiety. As an example, 3 reacts with dimethyl acetylenedicarboxylate, carbon disulfide, and cyclo-octasulfur, producing dimethyl phthalate, dithiopyrone, and thiophene, respectively. Carbon monoxide reacts with 3 in the presence of TlPF6, yielding [(triphos)Rh(η4-C4H4CO)]PF6 (10), which contains an unsubstituted cyclopentadienone ligand. By treatment with H2, 3 transforms into the η4-butadiene derivative [(triphos)Rh(η4-C4H6)]BPh4 (13). The chemistry of 3 has been compared to and contrasted with that of the related perpendicular μ-C2H2 complex [(triphos)Rh(μ-Cl)(μ-η2,η2-C 2H2)Rh(triphos)]Cl (2). From this study it is concluded that coupling of two or more metal centers at acetylene may lead to inactive complexes for catalytic transformations of acetylene.
Organorhodium(I) and -rhodium(III) complexes containing the ligand 1,1,1-tris((diphenylphosphino)methyl)ethane (triphos)
Johnston, Gregory G.,Baird, Michael C.
, p. 1894 - 1903 (2008/10/08)
Treatment of the complex [Rh(CO)2(triphos)]PF6 (triphos = MeC(CH2PPh2)3) with the ligands L (L = PMe3, PMe2Ph, PEt3, P(n-Bu)3, P(OMe)3, t-BuNC) resulted in the formation of complexes of the type [Rh(CO)L(triphos)]PF6. The analogous complexes of PPh3, ethylene, and propylene could not be prepared in this way but were synthesized by displacing molecular hydrogen from the complex [RhH2(CO)(trip-hos)]PF6, prepared by the photochemical oxidative addition of H2 to [Rh(CO)2(triphos)]PF6. The σ-bonded organorhodium(I) complexes RhR(CO)(triphos) (R = Me, Ph) were prepared by treating RhCl(CO)(triphos) with the appropriate alkyllithium reagent, and these compounds in turn were found to react readily with CO to form the acyl complexes Rh(RCO)(CO)(triphos). Addition of anhydrous HCl to the complex RhCl(CO)(triphos) resulted in the formation of a mixture of RhHCl2(CO)(triphos) and RhCl3(triphos), while addition of excess chlorine, bromine, or iodine to [Rh(CO)2(triphos)]PF6 resulted in the formation of the rhodium(III) complexes [RhX2(triphos)]PF6 (X = Cl, Br, I). These reacted in turn with methyllithium to form RhMe3(triphos), and with a variety of neutral ligands L to form the series [RhX2L(triphos)]PF6.
SOME RHODIUM(I) AND RHODIUM(III) COMPLEXES WITH THE TRIPOD-LIKE LIGANDS RC(CH2PPh2)3 (R=Me: triphos; R=Et: triphos-I) AND THE X-RAY CRYSTAL STRUCTURE OF
Ott, J.,Venanzi, L. M.,Ghilardi, C. A.,Midollini, S.,Orlandini, A.
, p. 89 - 100 (2007/10/02)
The syntheses of (8, triphos=CH3C(CH2PPh2)3) and the related compound (triphos-I=EtC(CH2PPh2)3) are described, and the X-ray crystal structure of the latter is reported.The crystals are monoclinic space group P21/a, a 15.985(6), b 19.683(7), c 11.900(4) Angstroem, β 103,73(6) degree, Z=4.The structure was solved by the heavy atom method and refined by full-matrix leastsquares to the conventional R factor value of 0.057 for 2649 observed reflections.The metal atom is octahedrally coordinated by three phophorus atoms and by three hydrogen atoms, each trans to one phosphorus.Complex 8 has been shown to react with CO to give (2).Compound 2 reacts with CH2=CHCO2Me to give only the branched insertion product .The complex has been re-investigated and was obtained in a single isomeric form which has been assigned a five-coordinate structure.The five-coordinate compounds (X=Br and I) are also described.
