In honour of the 70th birthday of Professor Luis A. Oro

EssayWhen Professor Luis Oro turns over the middle of June, he will be 70 years old, and he will be completing a cycle of almost half a century (48 years) dedicated to chemical research in the field of organometallics and homogeneous catalysis, and in general to the development of chemistry. In this aim, he has assumed different and complementary responsibilities, from leading innovative research projects, to the formation of professional scientists for academia or the chemical industry, from the direction of the Spanish Royal Society of Chemistry, to that of diverse editorial management consortia or even having taken the responsibility of guiding the overall Spanish scientific policy. It has been a long trek done with tons of enthusiasm, excellent companions and plenty of generosity. It is our pleasure and privilege to walk around the main steps of Professor Oro’s life; a life dedicated to investigate and to work to situate chemical research, and science in general, in the proper place it should be in our modern society.Peer Reviewe

Intramolecular C-H oxidative addition to iridium(I) triggered by trimethyl phosphite in N,N′-diphosphanesilanediamine complexes

The reaction of [Ir(SiNP)(cod)][PF] ([1][PF]) and of IrCl(SiNP)(cod) (5) (SiNP = SiMe{N(4-CHCH)PPh}) with trimethyl phosphite affords the iridium(iii) derivatives of the formula [IrHCl(SiNP-H){P(OMe)}] (x = 0, 3; x = 1, 6) containing the κC,P,P′-coordinated SiNP-H ligand (SiNP-H = Si(CH)(CH){N(4-CHCH)PPh}). The thermally unstable pentacoordinated cation [Ir(SiNP){P(OMe)}(cod)] (2) has been detected as an intermediate of the reaction and has been fully characterised in solution. Also, the mechanism of the C-H oxidative addition has been elucidated by DFT calculations showing that the square planar iridium(i) complexes of the formula [IrCl(SiNP){P(OMe)}] (x = 0, 4; x = 1, 7) should be firstly obtained from 2 and finally should undergo the C-H oxidative addition to iridium(i) via a concerted intramolecular mechanism. The influence of the counterion of 2 on the outcome of the C-H oxidative addition reaction has also been investigated.Financial support from Spanish “Ministerio de Economía y Competitividad” (CTQ2013–42532–P), “Diputación General de Aragón” (Group E07) and University of Zaragoza (UZCUD2014–CIE–13) is gratefully acknowledged.Peer Reviewe

Intramolecular C-H oxidative addition to iridium(I) in complexes containing a N,N'-diphosphanosilanediamine ligand

The iridium(I) complexes of formula Ir(cod)(SiNP)+ (1+) and IrCl(cod)(SiNP) (2) are easily obtained from the reaction of SiMe2{N(4-C6H4CH3)PPh2}2 (SiNP) with [Ir(cod)(CH3CN)2]+ or [IrCl(cod)]2, respectively. The carbonylation of [1][PF6] affords the cationic pentacoordinated complex [Ir(CO)(cod)(SiNP)]+ (3+), while the treatment 2 with CO gives the cation 3+ as an intermediate, finally affording an equilibrium mixture of IrCl(CO)(SiNP) (4) and the hydride derivative of formula IrHCl(CO)(SiNP–H) (5) resulting from the intramolecular oxidative addition of the C–H bond of the SiCH3 moiety to the iridium(I) center. Furthermore, the prolonged exposure of [3]Cl or 2 to CO resulted in the formation of the iridium(I) pentacoordinated complex Ir(SiNP–H)(CO)2 (6). The unprecedented κ3C,P,P′ coordination mode of the [SiNP–H] ligand observed in 5 and 6 has been fully characterized in solution by NMR spectroscopy. In addition, the single-crystal X-ray structure of 6 is reported.Financial support from Spanish “Ministerio de Economía y Competitividad” (CTQ2010– 15221) and “Diputación General de Aragón” (Group E07) is gratefully acknowledged.Peer Reviewe

gem-selective cross-dimerization and cross-trimerization of alkynes with silylacetylenes promoted by a Rhodium-Pyridine-N-heterocyclic carbene catalyst

The gem-selective cross-dimerization and -trimerization of silylacetylenes with alkynes through C[BOND]H activation using a rhodium(I)–pyridine–N-heterocyclic carbene catalyst have been developed. This reaction is applied to various aliphatic or aromatic terminal alkynes, internal alkynes, and gem-1,3-disubsituted enynes to afford the corresponding enynes and dienynes with high regio- and stereoselectivities and in good isolated yields (up to 91 %).Financial support from the Spanish Ministerio de Economía y Competitividad (MEC/FEDER) of Spain Project (CTQ2010-15221), the Diputación General de Aragón (E07), the KFUPMUNIZAR agreement, and CONSOLIDER INGENIO-2010, under the Project MULTICAT (CSD2009-00050) are gratefully acknowledged. L. R.-P. thanks CONACyT (Mexico, 186898 and 204033) for a postdoctoral fellowship.Peer Reviewe

Efficient Rhodium-catalyzed multicomponent reaction for the synthesis of novel propargylamines

[{Rh(μ-Cl)(H)2(IPr)}2] (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazole-2-ylidene) was found to be an efficient catalyst for the synthesis of novel propargylamines by a one-pot three-component reaction between primary arylamines, aliphatic aldehydes, and triisopropylsilylacetylene. This methodology offers an efficient synthetic pathway for the preparation of secondary propargylamines derived from aliphatic aldehydes. The reactivity of [{Rh(μ-Cl)(H)2(IPr)}2] with amines and aldehydes was studied, leading to the identification of complexes [RhCl(CO)IPr(MesNH2)] (MesNH2 = 2,4,6-trimethylaniline) and [RhCl(CO)2IPr]. The latter shows a very low catalytic activity while the former brought about reaction rates similar to those obtained with [{Rh(μ-Cl)(H)2(IPr)}2]. Besides, complex [RhCl(CO)IPr(MesNH2)] reacts with an excess of amine and aldehyde to give [RhCl(CO)IPr{MesN[DOUBLE BOND]CHCH2CH(CH3)2}], which was postulated as the active species. A mechanism that clarifies the scarcely studied catalytic cycle of A3-coupling reactions is proposed based on reactivity studies and DFT calculations.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) (CONSOLIDER INGENIO CSD2009-0050, CTQ2011-27593, CTQ2012-35665 and CTQ2013-42532-P projects) and the DGA/FSE-E07. The support from KFUPM-University of Zaragoza research agreement and the Centre of Research Excellence in Petroleum Refining & KFUPM is gratefully acknowledged. V. P. thankfully acknowledges the resources from the supercomputer >Memento>, technical expertise and assistance provided by BIFI-ZCAM (Universidad de Zaragoza). L.R.-P thanks to CONACyT for a postdoctoral fellowship (204033).Peer Reviewe

In-flow photocatalytic oxidation of NO on glasses coated with nanocolumnar porous TiO2 thin films prepared by reactive sputtering

The magnetron sputtering technique has been successfully employed for the preparation of porous TiO2 thin films on soda-lime glasses by means of an oblique angle deposition strategy. The morphology of the thin layers is affected by the deposition parameters, such as, the angle with respect to the target, applied power, total pressure, oxygen pressure and deposition time. It has been shown that 60–65° angles, lead to a compromise between the porosity, the level of oxidation and the thickness of the film. High total pressures of the deposition process result in less dense coatings of greater porosity. Moreover, the oxygen flow during the deposition process must be carefully adjusted for each set of deposition conditions, in order to achieve an optimum degree of oxidation. The evaluation of coated-glasses in the in-flow photocatalytic oxidation of nitrogen oxide has shown that the presence of a porous film is essential to achieve photocatalytic activity. The best performing coated-glass was able to reduce the NO concentration ca. 20% for 5 h. SEM and TEM images of this film show a microstructure composed of nanometric grains and a tilted columnar structure. Nanocrystal electron diffraction, XRD and Raman spectroscopy have confirmed the deposition of TiO2 anatase

Rhodium(I) complexes with hemilabile phosphines: Rational design for efficient oxidative amination catalysts

13 páginas, 10 figuras, 6 tablas, 4 esquemas.A series of cationic square-planar rhodium(I) complexes of type [Rh(cod){Ar2P(CH2)nZ}]+, [Rh(cod){Ar2P(CH2)nZ}2]+, and [Rh{Ar2P(CH2)nZ}2]+, which contained diverse functionalized hemilabile phosphine ligands of type Ar2P(CH2)nZ (n=1–3; Z=OMe, OEt, OnBu, NMe2, SMe), were synthesized and spectroscopically characterized. The crystal structures of representative compounds were determined by X-ray diffraction. Most complexes were active catalysts for the anti-Markovnikov oxidative amination of styrene with piperidine to produce (E)-1-styrylpiperidine. Catalyst screening showed a remarkable relationship between the hemilabile ligand, the precatalyst structure, and the catalytic activity. The more-efficient catalysts were those that had arylphosphine ligands with a 2-alkoxyethyl- or 3-alkoxypropyl hemilabile moiety, Ar2P(CH2)nOR (n=2, 3; R=Me, Et, nBu). This study has revealed the outstanding catalytic activity of bis-phosphine complexes [Rh{(4-R-C6H4)2P(CH2)3OEt}2][PF6] (R=H, Me, OMe), with unprecedented turnover frequencies of up to 80 h−1 (R=Me) and excellent enamine selectivity (96 %).Financial support from the Ministerio de Ciencia e Innovación (MICINN/FEDER): CTQ2010-15221, MULTICAT (CSD2009-00050), and Factoría de Cristalización (CSD2006-0015) is gratefully acknowledged. M.I.B. thanks the Spanish MICINN and the IUCH (Instituto Universitario de Catálisis Homogénea) for a predoctoral fellowship.Peer reviewe

Tetranuclear [Rh4(μ-PyS2) 2(diolefin)4] complexes as building blocks for new inorganic architectures: Synthesis of coordination polymers and heteropolynuclear complexes with electrophilic d8 and d10 metal fragments

The reaction of [Rh4(μ-PyS2)2(cod) 4] (PYS2 = 2,6-pyridinedithiolate, cod = 1,5-cyclooctadiene) with CF3SO3Me gave the cationic complex [Rh4(μ-PyS2Me)2(cod) 4][CF3SO3]2 (1) with two 6-(thiomethyl)pyridine-2-thiolate bridging ligands from the attack of Me+ at the terminal sulfur atoms of the starting material. Under identical conditions [Rh4(μ-PyS2)2(tfbb)4] (tfbb = tetrafluorobenzobarrelene) reacted with CF3SO3Me to give the mixed-ligand complex [Rh4(μ-PyS2)(μ-PyS 2Me)(tfbb)4][CF3SO3] (2). The nucleophilicity of the bridging ligands in the complexes [Rh4(μ -PyS2)2(diolefin)4] was exploited to prepare heteropolynuclear species. Reactions with [Au(PPh3)(Me 2CO)][ClO4] gave the hexanuclear complexes [(PPh 3)2Au2Rh4(μ-PyS2) 2(diolefin)4][ClO4]2 (diolefin = cod (3), tfbb (4)). The structure of 4, solved by X-ray diffraction methods, showed the coordination of the [Au(PPh3)]+ fragments to the peripheral sulfur atoms in [Rh4(μ-PyS2) 2(diolefin)4 along with their interaction with the neighbor rhodium atoms. Neutral coordination polymers of formula [CIMRh 4(μ-PyS2)2(diolefin)4] n (M = Cu (5, 6), Au (7)) result from the self-assembly of alternating [Rh4(μ-PyS2)2(diolefin) 4] ([Rh4]) blocks and MCI linkers. The formation of the infinite polymetallic chains was found to be chiroselective for M = Cu; one particular chain contains exclusively homochiral [Rh4] complexes. Cationic heterometallic coordination polymers of formula [MRh 4(μ-PyS2)2(diolefin)4] n (M = Ag (8, 9), Cu (10, 11)) and [Rh5(μ-PyS 2)2(diolefin)5]n[BF 4]n (12, 13) result from the reactions of [Rh 4] with [Cu(CH3CN)4]BF4, AgBF 4, and [Rh(diolefin)(Me2CO)2]BF4, respectively. The heterometallic coordination polymers exhibit a weak electric conductivity in the solid state in the range (1.2-2.8) × 10-7 S cm-1.The financial support from Ministerio de Ciencia y Tecnología (MCyT(DGI)/FEDER, Projects BQU2002-00074 and BQU2000-1170) is gratefully acknowledged.Peer Reviewe

Oxidation and β-alkylation of alcohols catalysed by Iridium(I) complexes with functionalised N-heterocyclic Carbene ligands

The borrowing hydrogen methodology allows for the use of alcohols as alkylating agents for C-C bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)-cyclooctadiene complexes having a NHC ligand with a O- or N-functionalised wingtip efficiently catalysed the oxidation and β-alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH)(cod)(MeIm(2- methoxybenzyl))][BF] (cod=1,5-cyclooctadiene, MeIm=1-methylimidazolyl) having a rigid O-functionalised wingtip, shows the best catalyst performance in the dehydrogenation of benzyl alcohol in acetone, with an initial turnover frequency (TOF) of 1283 h, and also in the β-alkylation of 2-propanol with butan-1-ol, which gives a conversion of 94 % in 10 h with a selectivity of 99 % for heptan-2-ol. We have investigated the full reaction mechanism including the dehydrogenation, the cross-aldol condensation and the hydrogenation step by DFT calculations. Interestingly, these studies revealed the participation of the iridium catalyst in the key step leading to the formation of the new C-C bond that involves the reaction of an O-bound enolate generated in the basic medium with the electrophilic aldehyde.Financial support from the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER, Project CTQ2013-42532-P), MICINN (Project Consolider Ingenio 2010 CSD2009-00050) and Diputación General de Aragón (DGA/FSE-E07) is gratefully acknowledged. J.F.-T. thanks the Spanish MICINN for a predoctoral fellowship.Peer Reviewe

Tuning PCP-Ir complexes: the impact of an N-heterocyclic olefin

A new PCP-type ligand based on an N-heterocyclic olefin (NHO) scaffold has been prepared. The flexibility of this ligand, which is able to adopt facial coordination modes in Ir(I) or meridional in Ir(III) complexes, can be attributed to the dual nature (ylide–olefin) of the NHO scaffold. This results in a rare case of olefin “slippage” that is supported by X-ray crystallography and DFT calculations.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) (CONSOLIDER INGENIO CSD2009-0050, CTQ2011-27593 and CTQ2012-35665 projects) and the DGA/FSE-E07. The support from KFUPM-University of Zaragoza research agreement and the Centre of Research Excellence in Petroleum Refining & KFUPM is gratefully acknowledged.Peer Reviewe