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13 results on '"Pérez-Torrente, J. J."'

1. Reactivity of [TiM2] (M = Rh, Ir) and [TiIr3] early-late heterobimetallic sulfido-bridged clusters

Author

Casado, M. A., Ciriano, M. A., Lahoz, F. J., Oro, L. A., and Pérez-Torrente, J. J.

Abstract

Treatment of heterobimetallic sulfido-bridged complexes Cp(acac)Ti(µ3-S)2(M(cod))2] (M = Rh (1), Ir (2)) with the organic acids CX3COOH (X = F, H) forms the corresponding acetate derivatives Cp(CX3COO)Ti(µ3-S)2(M(cod))2] (X = F, M = Rh (3), Ir (4); X = H, M = Rh (5), M = Ir (6)). While complex 3 was easily isolated, compounds 4-6 establish in solution the corresponding equilibria with the starting complexes 1 and 2. Treatment of 1 with a hydrochloric acid solution in THF generates the heterohexanuclear cationic cluster (CpTi(µ3-S)2(Rh(cod))2)2(µ-OH)]Cl] (7), which is deprotonated with weak bases affording the oxo derivative (CpTi(µ3-S)2(Rh(cod))2)2(µ2-O)] (8). Cluster 8, and the analogous with the ligand methylcyclopentadienyl ((CpMe)Ti(µ3-S)2(Rh(cod))2)2(µ2-O)] (9), can be synthesized from reaction of the respective complexes Cp2Ti(SH)2] and (CpMe)2Ti(SH)2] with the methoxo-bridged dinuclear complex (Rh(µ-OMe)(cod))2] in the presence of water. A preliminary study of the molecular structure of 9 confirmed the formation of an almost linear array of the "Ti-O-Ti" subunit, in which each titanium atom supports two "Rh(cod)" moieties through two sulfido bridges. Further, the heterotetranuclear cluster CpTi(µ3-S)3Ir3(µ2-CO)(CO)3(PMe3)3] (10) reacts with alkynes at the triiridium metallic triangle. The reactions with activated alkynes, such as dimethyl acetylenedicarboxylate (or diethyl acetylenedicarboxylate) afford clusters CpTi(µ3-S)3Ir3(µ2-¿1-RO2CCCCO2R)(C(O)RO2CCCCO2R)(CO)3(PMe3)3] (R = Me (11), Et (12)), which incorporate two molecules of alkyne. The X-ray molecular structure of 11 shows that one alkyne is cis-metallated to the metal-metal bonded iridium centres whereas the other is taking part of a iridacyclobutenone moiety resulting from the CO migratory insertion into a iridium-alkyne bond at the third iridium centre. However, reaction of 10 with phenylacetylene stops at the cluster CpTi(µ3-S)3Ir3(µ2-¿1-PhCCH)(CO)3(PMe3)3] (13), which contains only a cis-metallated olefin to two metal-metal bonded iridium atoms. The X-ray molecular structure of CpTi(µ3-S)3Ir3(µ2-¿1-PhCCH)(H)(CO)3(PMe3)3]BF4] (14), the product resulting from protonation of 13 with HBF4·OEt2 shows that the TiIr3] core remains intact and that the olefin is indeed cis-metallated to the two metal-metal bonded iridium atoms, while the third iridium atom from the metallic triangle becomes protonated.

Published
2016

13. Synthesis of paramagnetic tetranuclear rhodium and iridium complexes with the 2,6-pyridinedithiolate ligand. Redox-induced degradation to diamagnetic triiridium compounds.

Author

Casado MA, Pérez-Torrente JJ, López JA, Ciriano MA, Alonso PJ, Lahoz FJ, and Oro LA

Subjects
Crystallography, X-Ray, Electrochemistry, Electron Spin Resonance Spectroscopy, Indicators and Reagents, Magnetics, Oxidation-Reduction, Spectrophotometry, Infrared, Chelating Agents chemistry, Iridium chemistry, Pyridines chemistry, Rhodium chemistry
Abstract

The tetranuclear complexes [M4(mu-PyS2)2(diolefin)4] [PyS2 = 2,6-pyridinedithiolate; M = Rh, diolefin = cod (1,5-cyclooctadiene) (1), tfbb (tetrafluorobenzo[5,6]bicyclo[2.2.2]octa-2,5,7-triene) (2); M = Ir, diolefin = cod (3), tfbb (4)] exhibit two one-electron oxidations at a platinum disk electrode in dichloromethane at potentials accessible by chemical reagents. The rhodium tetranuclear complexes were selectively oxidized to the monocationic complexes [Rh4(mu-PyS2)2(diolefin)4](+) (1(+), 2(+)) by mild one-electron oxidants such as [Cp2Fe](+) or [N(C6H4Br-4)3](+) and isolated as the PF6(-), BF4(-), and ClO4(-) salts. Silver salts behave as noninnocent one-electron oxidants for the reactions with the rhodium complexes 1 and 2 since they give sparingly soluble coordination polymers. The complex [Ir4(mu-PyS2)2(cod)4](+) (3(+)) was obtained as the tetrafluoroborate salt by reaction of 3 with 1 molar equiv of AgBF4, but the related complex 4(+) could not be isolated from the chemical oxidation of [Ir4(mu-PyS2)2(tfbb)4] (4) with AgBF4. Oxidation of 3 and 4 with 2 molar equiv of common silver salts resulted in the fragmentation of the complexes to give the diamagnetic triiridium cations [Ir3(mu-PyS2)2(diolefin)3](+). The molecular structure of [Ir3(mu-PyS2)2(cod)3]BF4, determined by X-ray diffraction methods, showed the three metal atoms within an angular arrangement. Both 2,6-pyridinedithiolate tridentate ligands bridge two metal-metal bonded d(7) centers in pseudo octahedral environments and one d(8) square-planar iridium center. An interpretation of the EPR spectra of the 63-electron mixed-valence paramagnetic tetranuclear complexes suggests that the unpaired electron is delocalized over two of the metal atoms in the complexes 1(+)-3(+).

Published
2001
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