Browsing by Author "Ristic Petrovic, Dusan"
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- ItemDouble activation of the geminal carbon−hydrogen bonds in 1,3-butadiene by a diiridium complex(2000) Ristic Petrovic, Dusan; Torkelson, Jeffrey R.; Hilts, Robert; McDonald, Robert; Cowie, MartinThe binuclear complex [Ir2(CH3)(CO)2(dppm)2][CF3SO3] (1) (dppm = Ph2PCH2PPh2) reacts with 1,3-butadiene at ambient temperature over a 48 h period to give the vinylvinylidene-bridged product [Ir2(CH3)(H)(CO)2(μ-H)(μ-CC(H)C(H)CH2)(dppm)2][CF3SO3] (2). At −55 °C the same reactants yield the 1,3-butadiene adduct [Ir2(CH3)(CO)2(μ-η2:η2-H2CC(H)C(H)CH2)(dppm)2][CF3SO3] (3), in which the diolefin binds in an s-trans geometry on one face of the complex. A proposal is advanced rationalizing the conversion of 3 to 2 upon warming.
- ItemRuthenium carbonyl complexes of the bridging tetradentate ligands Ph4P2N4S2 and Ph4P2N4S2Me(1995) Chivers, Tristram; Hilts, Robert; Parvez, Masood; Ristic Petrovic, DusanThe reaction of Ru(CO)4(C2H4) or Ru(CO)5 with 1,5-Ph4P2N4S2 in CH2Cl2-hexane at 23 °C produces the dimer [Ru(CO)2(Ph4P2N4S2)]2 (4) in 54% and 11% yields, respectively. The treatment of 4 with methyl triflate (1:1 molar ratio) in dichloromethane yields the mono(N-methylated) derivative [Ru2(CO)4(Ph4P2N4S2)(Ph4P2N4S2Me)][CF3SO3] (5) or, in a 1:2 molar ratio, the dimethylated derivative [Ru(CO)2(Ph4P2N4S2Me)]2[CF3SO3]2, which exists as a ca. equal mixture of two symmetrical isomers on the basis of 1H and 31P NMR, and IR spectra. The reaction of 4 with two equivalents of Me3NO in the presence of acetonitrile generates [Ru(CO)(CH3CN)(Ph4P2N4S2)]2, which is also formed as a mixture of isomers in a ratio of ca. 2:1 on the basis of 1H and 31P NMR, and IR spectra. The X-ray structure of 4•CH2Cl2 shows that the P2N4S2 ring is bonded to one ruthenium through two (geminal) nitrogen atoms and the remote sulfur atom while the second sulfur atom acts as a bridge to the other ruthenium. The crystals of 4•CH2Cl2 are triclinic, space group with a = 12.901(1) Å, b = 13.072(1) Å, c = 10.123(1) Å, α = 100.88(1)°, β = 98.90(1)°,γ = 67.50(1)°, V = 1542.4(3) Å3, and Z = 2. The final R and Rw, values were 0.040 and 0.027, respectively. The X-ray structure of 5 reveals that N-methylation does not significantly perturb the bonding between the heterocyclic ligand and ruthenium. The crystals of 5 are triclinic, space group with a = 12.912(6) Å, b = 13.435(7) Å, c = 9.948(3) Å, α = 105.04(3)°, β = 102.85(3)°, γ = 70.74(4)°, V = 1555(1) Å3, and Z = 2. The final R and Rw values were 0.063 and 0.071, respectively. Keywords: ruthenium, tetradentate ligand, P2N4S2 ring.