Bis(hydrosulfido)-bridged dinuclear rhodium(I) complexes as a platform for the synthesis of trinuclear sulfido aggregates with the core [MRh2(μ3-S2)] (M = Rh, Ir, Pd, Pt, Ru)

The reaction of [Rh(μ-SH)(CO)(PPh3)]2 or [Rh(μ-SH){P(OPh)3}2]2 with [Cp*MCl2]2 (M = Rh, Ir) in the presence of NEt3 afforded the Rh3 and IrRh2 sulfido-bridged compounds [Cp*M(μ3-S)2Rh2(CO)2(PPh3)2] (M = Rh, 1; Ir, 2) and [Cp*Rh(μ3-S)2Rh2{P(OPh)3}4] (3). The reaction with [MCl2(cod)] (M = Pd, Pt), cis-[PtCl2(PPh3)2] or [(η6-C6H6)RuCl2]2 under the same experimental conditions gave [(cod)M(μ3-S)2Rh2{P(OPh)3}4] (M = Pd, 6; Pt, 7), [(cod)M(μ3-S)2Rh2(CO)2(PPh3)2] (M = Pd, 8; Pt, 9), [(PPh3)2Pt(μ3-S)2Rh2(CO)2(PPh3)2] (10) and [(η6-C6H6)Ru(μ3-S)2Rh2(CO)2(PPh3)2] (12), with PdRh2, PtRh2 and RuRh2 trimetallic cores. The aggregates derived from [Rh(μ-SH)(CO)(PPh3)]2 were isolated as a mixture of trans and cis isomers in which the trans isomer predominates. The reaction of [Rh(μ-SH){P(OPh)3}2]2 with 2 equiv. of n-BuLi at 253 K followed by addition of [Cp*IrCl2]2 gave [Cp*Ir(μ3-S)2Rh2{P(OPh)3}4] (4) and [Cp*2ClIr2(μ3-S)2Rh{P(OPh)3}2] (5) in a 3:2 ratio. The RuRh2 compound [(η6-C6H6)Ru(μ3-S)2Rh2{P(OPh)3}4] (11) was prepared similarly from [Rh(μ-SH){P(OPh)3}2]2 and [(η6-C6H6)RuCl2]2 using n-BuLi as a deprotonating agent. The molecular structures of compounds 3, 6, 7, 9 and 11 have been determined by X-ray analysis. The trinuclear complexes exhibit an asymmetric triangular metal core with two triply bridging sulfido ligands resulting in a distorted trigonal-bipyramidal M3(μ3-S)2 heterometallic metal–sulfur core.Financial support from the Ministerio de Ciencia e Innovación (MICINN/FEDER) of Spain (Project CTQ2010-15221), the Diputación General de Aragón (E07), and CONSOLIDER INGENIO-2010, Projects MULTICAT (CSD2009-00050) and Factoría de Cristalización (CSD2006-0015) is gratefully acknowledged.Peer Reviewe

Synthesis of a square-planar rhodium alkylidene N-heterocyclic carbene complex and its reactivity toward alkenes

The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl(-CHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of the ¿2-olefin complexes RhCl(¿2-CH2-CHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate

Brønsted acid/base driven chemistry with rhodathiaboranes: A labile {SB 9H 9}-thiadecaborane fragment system

Reversible H 2 cleavage promoted by closo to nido transformations of [1,1-(PPh 3) 2-3-(NC 5H 5)-closo-1, 2-RhSB 9H 8] (2)/[8,8,8-(PPh 3) 2(H)-9-(NC 5H 5)-nido-8,7-RhSB 9H 9] (1) is a cooperative action with application in catalysis; the treatment of 2 and [1,1-(PPh 3)(CO)-3-(NC 5H 5)-closo-RhSB 9H 8] (3) with either HCl or HOTf in CH 2Cl 2 affords the 11-vertex nido-rhodathiaboranes [8,8-(PPh 3)(Cl)-9-(NC 5H 5)-nido-8,7-RhSB 9H 9] (4) and [8,8,8-(PPh 3)(CO)(Cl)-9-(NC 5H 5)-nido-8,7-RhSB 9H 9] (5), respectively. In contrast, the reaction of 1 with triflic acid yields the salt [8,8-(PPh 3) 2(H)-9-(NC 5H 5)-nido- RhSB 9H 10][OTf] (6). These results illustrate the bifunctional nature of the clusters and their nido to closo redox flexibility, which open new routes for the tuning of the reactivity of these polyhedral compounds and widen their potential applications. © 2011 American Chemical Society.We acknowledge the Spanish Ministry of Science and Innovation (CTQ2009-10132, CONSOLIDER INGENIO, CSD2009-00050, MULTICAT and CSD2006-0015, Crystallization Factory) for support of this work. B.C. thanks the “Diputación General de Aragón” for a predoctoral scholarship and ESRF BM16 beamline staff for their support on data acquisition of 5.Peer Reviewe

Chemistry of 11-vertex rhodathiaboranes: reactions with monodentate phosphines

The reaction of [8,8-(PPh3)2-nido-8,7-RhSB 9H10] (1) with PR3 in a 1:2 ratio affords mixtures that contain the mono-substituted bis-PR3-ligated rhodathiaboranes [8,8-(PPh3)(L)-nido-8,7-RhSB9H 10] [L = PMe2Ph (5), PMe3 (6)] and the corresponding tris-PR3-ligated compounds [8,8,8-(L) 3-nido-8,7-RhSB9H10] [L = PMe2Ph (7), PMe3 (8)]. These latter species are more conveniently prepared from the reaction of 1 with three equivalents of the monodentate phosphines, PMe2Ph and PMe3. Reaction between 1 and PMePh2 in a 1:2 ratio yields the disubstituted rhodathiaborane [8,8-(PMePh 2)2-nido-8,7-RhSB9H10] (4), whereas the use of three equivalents of phosphine leads to the formation of B-ligated eleven-vertex [8,8,8-(PMePh2)2(H)-nido-8,7-RhSB 9H9-9-(PMePh2)] (9). Compounds 4-9 have been characterized by NMR spectroscopy, and the structures of 8 and 9 confirmed by X-ray diffraction analyses. The characterization of the cluster compounds has been aided by the use of DFT calculations on some of the species. Variable-temperature NMR studies have demonstrated a lability of the PMePh 2 ligands in compounds 4 and 9, providing mechanistic insights about the ligand substitutional chemistry in these eleven-vertex rhodathiaboranes. © 2011 The Royal Society of Chemistry.We acknowledge the Spanish Ministry of Science and Innovation (CTQ2009-10132, CONSOLIDER INGENIO, CSD2009-00050, MULTICAT and CSD2006-0015, Crystallization Factory) for support of this work.Peer Reviewe

Synthesis, structure, and kinetic studies on [RuCl2(NCCH3)2(cod)]

[RuCl2(NCCH3)2(cod)], an alternative starting material to [RuCl2(cod)] n for the preparation of ruthenium(II) complexes, has been prepared from the polymer compound and isolated in yields up to 87% using a new work-up procedure. The compound has been obtained as a yellow solid without water of crystallization. The complexes [RuCl2(NCR)2(cod)] spontaneously transform into dimers [Ru2Cl(μ-Cl)3(cod)2(NCR)] (R = Me, Ph). 1H NMR kinetic experiments for these transformations evidenced first-order behavior. [RuCl2(NCPh)2(cod)] dimerizes slower by a factor of ten than [RuCl2(NCCH3)2(cod)]. The following activation parameters, ΔH # = 114 ± 3 kJ mol−1 and ΔS # = 66 ± 9 J K−1 mol−1 for R = CH3CN (ΔG # = 94 ± 5 kJ mol−1, 298.15 K) and ΔH # = 122 ± 2 kJ mol−1 and ΔS # = 75 ± 6 J K−1 mol−1 for R = Ph (ΔG # = 100 ± 4 kJ mol−1, 298.15 K), have been calculated from the first-order rate constants in the temperature range 294–323 K. The kinetic parameters are in agreement with a two-step mechanism with dissociation of acetonitrile as the rate-determining step. The molecular structures of [Ru2Cl(μ-Cl)3(cod)2(NCR)] (R = Me, Ph) have been determined by X-ray diffraction.Financial support from the Ministerio de Ciencia e Innovación (MICINN/FEDER) of Spain (Project CTQ2010-15221), Diputación General de Aragón (E07) and CONSOLIDER INGENIO-2010, Projects MULTICAT (CSD2009-00050) and Factoría de Cristalización (CSD2006-0015), is gratefully acknowledged.Peer reviewe

Iridium(I) complexes with hemilabile N-heterocyclic carbenes: Efficient and versatile transfer hydrogenation catalysts

16 páginas, 5 figuras, 3 tablas, 3 esquemas.A series of neutral and cationic rhodium and iridium(I) complexes based on hemilabile O-donor- and N-donor-functionalized NHC ligands having methoxy, dimethylamino, and pyridine as donor functions have been synthesized. The hemilabile fragment is coordinated to the iridium center in the cationic complexes [Ir(cod)(MeImR)]+ (R = pyridin-2-ylmethyl, 3-dimethylaminopropyl) but remains uncoordinated in the complexes [MBr(cod)(MeImR)], [M(NCCH3)(cod)(MeImR)]+ (M = Rh, Ir; R = 2-methoxyethyl and 2-methoxybenzyl) and [IrX(cod)(MeImR)] (X = Br, R = pyridin-2-ylmethyl; X = Cl, R = 2-dimethylaminoethyl, 3-dimethylaminopropyl). The structure of [IrBr(cod)(MeIm(2-methoxybenzyl))] has been determined by X-ray diffraction. The iridium complexes are efficient precatalysts for the transfer hydrogenation of cyclohexanone in 2-propanol/KOH. A comparative study has shown that cationic complexes are more efficient than the neutral and also that complexes having O-functionalized NHC ligands provide much more active systems than the corresponding N-functionalized ligands with TOFs up to 4600 h–1. The complexes [Ir(NCCH3)(cod)(MeImR)]+ (R = 2-methoxyethyl and 2-methoxybenzyl) have been successfully applied to the reduction of several unsaturated substrates as ketones, aldehydes, α,β-unsaturated ketones, and imines. The investigation of the reaction mechanism by NMR and MS has allowed the identification of relevant alkoxo intermediates [Ir(OR)(cod)(MeImR)] and the unsaturated hydride species [IrH(cod)(MeImR)]. The β-H elimination in the alkoxo complex [Ir(OiPr)(cod)(MeIm(2-methoxybenzyl))] leading to hydrido species has been studied by DFT calculations. An interaction between the β-H on the alkoxo ligand and the oxygen atom of the methoxy fragment of the NHC ligand, which results in a net destabilization of the alkoxo intermediate by a free energy of +1.0 kcal/mol, has been identified. This destabilization facilitates the β-H elimination step in the catalytic process and could explain the positive effect of the methoxy group of the functionalized NHC ligands on the catalytic activity.Financial support from Ministerio de Ciencia e Innovación (MICINN/FEDER) is gratefully acknowledged (Projects: CTQ2010-15221, CSD2006-0015, and CSD2009-00050). J.F. T. thanks the Spanish MICINN for a predoctoral fellowship, and S.W. thanks the Eramus program (Univ. RWTH-Aachen, Germany).Peer reviewe

La necesidad de tratamiento dental en pacientes psiquiátricos hospitalizados

Este estudio determina las necesidades de tratamiento dental en una población de pacientes psiquiátricos hospitalizados, que comprendía a 347 hombres y 218 mujers, con una edad media de 58 años. El tiempo medio de hospitalización era de 26,1 años. La mayor proporción de pacientes (62%) eran esquizofrénicos. Todos los pacientes tomaban medicación psicotrópica, con una media de 2,1 psicofármacos. La población fue examinada de acuerdo con el criterio dental de la OMS, que mostraba unas necesidades dentales medias de 4 obturaciones y 4,1 extracciones por paciente, con un tiempo medio de intervención dental de 86,9 minutos. El tiempo medio de necesidades de tratamiento dental, significativamente, era más elevado en los hombres que en las mujeres, y descendía con la edad. Los enfermos mentales institucionalizados deben ser considerados como un grupo especial de población con grandes necesidades de tratamiento dental.This study assesses dental treatment needs of a hospitalized psychiatric population composed of 347 males and 218 females with a mean age of 58. The mean length of hospitalization was 26,1 years. The largest proportion of patients (62%) was diagnosed as having schizophrenia. All subjects were taking psychotropic drugs, with a mean number of 2. The population was examined according to the WHO dental criteria which showed a mean need for dental treatment were significantly, more highest among males than females, and decreased with age. The institutionalized mentally ill must be considered a special group with a high need for dental treatment

Synthesis of a square-planar rhodium alkylidene N-heterocyclic carbene complex and its reactivity toward alkenes

The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl(=CHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of the η2-olefin complexes RhCl(η2- CH2=CHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate. © 2011 American Chemical Society.Financial support from the Ministerio de Ciencia e Innovación (MICINN/FEDER) of Spain (Project CTQ2010-15221), the Diputación General de Aragón (E07), the ARAID Foundation under the program “Jóvenes Investigadores”, and CONSOLIDER INGENIO-2010, Projects MULTICAT (CSD2009-00050) and Factoría de Crystalización (CSD2006-0015), are gratefully acknowledged. R.C. thanks the CSIC and the European Social Fund for his Research Contract in the framework of the “Ramón y Cajal” Program.Peer Reviewe

New iridathiaboranes with reversible isonido ↔ nido cluster Flexibility

The reaction between [IrCl(CO)(PMe3)2] and the Cs[arachno-6-SB9H12] salt in CH2Cl2 yields pale-yellow 11-vertex [8,8,8-(CO)(PMe3)2-nido-8,7- IrSB9H10] (4). Reaction of this CO-ligated iridathiaborane with Me3N -O affords pale-yellow 11-vertex [1,1,1-(H)(PMe 3)2-isonido-1,2-IrSB9H9] (6), which is also formed from the thermal decarbonylation of 4. Compound 4 has a conventional cluster structure based on classical 11-vertex nido geometry, with the iridium center and the sulfur atom in the adjacent 8-and 7-positions on the pentagonal open face. Compound 6 exhibits an 11-vertex isonido structure based on an octadodecahedron with the {Ir(H)(PMe3)2} occupying the apical position of connectivity six, but with one long non-bonding Ir-B distance generating the quadrilateral isonido open-face. Compound 6 reverts to 4 upon reaction with CO, and the Lewis acid character of 6 is further demonstrated in the reaction with EtNC to give [8,8,8-(EtNC)(PMe 3)2-nido-8,7-IrSB9H10] (7). The three new compounds 4, 6, and 7 have been characterized by single-crystal X-ray diffraction analyses and by NMR spectroscopy. Each of the nido iridathiaboranes 4 and 7 exhibits two different {Ir(L)(PMe3)2}-to-{SB 9H10} conformers in solution and in the solid state. Density functional theory (DFT) calculations reveal that the iridium atom inverts the nido-isonido-closo energy profile previously found for the rhodathiaborane congener [8,8-(PPh3)2-nido-8,7-RhSB 9H10] (3), demonstrating how the structure of these 11-vertex clusters can be controlled and fine-tuned by the tailoring of the metal center. © 2010 American Chemical Society.We acknowledge the Spanish Ministry of Science and Innovation (CTQ2009-10132, CONSOLIDER INGENIO, CSD2009-00050, MULTICAT and CSD2006-0015, Crystallization Factory) for support of this work. R.M. thanks the MEC-Universidad de Zaragoza and the European Social Fund for his Research Contract in the framework of the “Ramón y Cajal” Program. J.B. was supported by the Diputación General de Zaragoza and Caja Inmaculada (Grant CB5/09); and, in part, by the Grant Agency of the Czech Republic, project no. 203/06/P398 and the Grant Agency of the Academy of Sciences of the Czech Republic, project no. IAA400320601.Peer Reviewe