Manuel Iglesias

• PhD in Chemistry
• Científico titular at Spanish National Research Council

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 suppor...

A well-defined NHC-Ir(III) catalyst, [Ir(H)2(IPr)(py)3][BF4] (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene), that provides access to a wide range of aryl- and heteroarylsilanes by intermolecular dehydrogenative C–H bond silylation has been prepared and fully characterized. The directed and non-directed functionalisation of C–H bonds has...

The catalysts [Ir(COD)(κ³-P,C,P′-PCNHCP)]BF4 and [Ir(COD)(κ²-P,C-PCNHCO)]BF4 proved to be active in the solventless dehydrogenation of formic acid. The impact of various cosolvents on the activity was evaluated, showing an outstanding improvement of the catalytic performance of [Ir(COD)(κ²-P,C-PCNHCO)]BF4] in “green” organic carbonates: namely, dim...

A sturdy iridium complex that features a PCP ligand based on an N-heterocyclic olefin shows remarkable activity for the solventless dehydrogenation of formic acid. Reactivity studies highlight the importance of...

This review summarises the most recent advances in Ir–NHC catalysis while revisiting all the classical reactions in which this type of catalyst has proved to be active. The influence of the ligand system and, in particular, the impact of the NHC ligand on the activity and selectivity of the reaction have been analysed, accompanied by an examination...

The dehydrogenative coupling of hydrosilanes with alcohols or water is a fundamental transformation in organosilicon chemistry, enabling the synthesis of alkoxysilanes, silanols, and siloxanes—key materials for coatings and adhesives. Traditionally, these reactions have relied on catalysts based on platinum group metals, which are costly and scarce...

The [2+2+2] cycloaddition of alkynes and nitriles is an efficient and atom-economic method for the synthesis of pyridines. However, most of the examples so far reported entail the use of...

This chapter reviews the state of the art of rhodium- and iridium-catalyzed hydrosilylation reactions, demonstrating the utility of rhodium and iridium catalysts for organic synthesis. Nowadays, this field has solid and proven mechanistic foundations that allow the design, development, and optimization of new catalytic systems. As this chemistry wi...

A new methodology for the preparation of Co(I)-NHC (NHC = N-heterocyclic carbene) complexes, namely, [Co(PCNHCP)(CO)2][Co(CO)4] (1) and [Co(PCNHCP)(CO)2]BF4 (2), has been developed (PCNHCP = 1,3-bis(2-(diphenylphosphanyl)ethyl)-imidazol-2-ylidene). Both complexes can be straightforwardly prepared by direct reaction of their parent imidazolium salts...

Correction for 'Iridium-(κ2-NSi) catalyzed dehydrogenation of formic acid: effect of auxiliary ligands on the catalytic performance' by Alejandra Gomez-España et al., Dalton Trans., 2023, 52, 6722-6729, https://doi.org/10.1039/d3dt00744h.

Correction for 'Iridium-(κ2-NSi) catalyzed dehydrogenation of formic acid: effect of auxiliary ligands on the catalytic performance' by Alejandra Gomez-España et al., Dalton Trans., 2023, https://doi.org/10.1039/d3dt00744h.

2 a and 2 b, [Ir(CI)(COD)(NHC)] (COD=1,5‐cyclooctadiene), have been prepared via transmetallation from NHC−Ag complexes. [Rh(CI)(COD)(NHC)] (4) was prepared analogously. [Ir({κ‐C,N‐(NHC‐acetamide−1H)}(COD)] (3 c) has been synthesized via transmetallation from the deprotonated NHC−Ag complex. [IrCp*({κ‐C,N‐(NHC‐acetamide−1H)}] (5) (Cp*=pentamethylcy...

The iridium(III) complexes [Ir(H)(Cl)(κ2-NSitBu2)(κ2-bipyMe2)] (2) and [Ir(H)(OTf)(κ2-NSitBu2)(κ2-bipyMe2)] (3) (NSitBu2 = {4-methylpyridine-2-yloxy}ditertbutylsilyl) have been synthesized and characterized including X-ray studies of 3. A comparative study of the catalytic activity of complexes 2, 3, [Ir(H)(OTf)(κ2-NSitBu2)(coe)] (4), and [Ir(H)(OT...

The novel P-N ligand 1-((diphenylphosphaneyl)methyl)-1H-benzo-1,2,3-triazole (1), based on a benzotriazole scaffold, has been prepared. The reaction of 1 with [CoCp*(CH3CN)3][BF4]2 and [CoCp*(I)2]2 (Cp* = pentamethylcyclopentadienyl) affords the chelate complexes [CoCp*(CH3CN)(P-N)][BF4]2 (2) and [CoCp*(I)(P-N)]I (3), respectively. Complexes 2 and...

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 pressu...

A combined ALD/MLD (where ALD and MLD stand for atomic and molecular layer deposition, respectively) deposition strategy using TiCl4, H2O and HQ (hydroquinone) as precursors has been applied for the preparation of inorganic–organic thin films on soda-lime glasses. The alternate deposition of TiO2 layers, by pulsing TiCl4/H2O (ALD), and hybrid layer...

Using a low loading of the iridium(III) complexes [Ir(CF3SO3)(κ2-NSiiPr)2] (1) (NSiiPr = (4-methylpyridin-2-yloxy)diisopropylsilyl) and [{Ir(κ2-NSiMe)2}2(μ-CF3SO3)2] (2) (NSiMe = (4-methylpyridin-2-yloxy)dimethylsilyl) in the presence of Et3N, it has been possible to achieve the solventless selective dehydrogenation of formic acid. The best catalyt...

Complex [(CNC)MesRh(PMe2Ph)]PF6 (1) has been found to be an effective catalyst for solventless formic acid (FA) dehydrogenation, affording exclusively H2 and CO2 as decomposition products. The effect of the addition...

Formic acid (FA) possesses a high volumetric concentration of H2 (53 g L−1). Moreover, it can be easily prepared, stored, and transported. Therefore, FA stands out as a potential liquid organic hydrogen carrier (LOHC), which allows storage and transportation of hydrogen in a safe way. The dehydrogenation to produce H2 and CO2 competes with its dehy...

In this chapter, homogeneous iridium-catalyzed silylation reactions are reviewed, focusing primarily on their synthetic utility. Additionally, relevant catalytic cycles are commented, paying especial attention to those that are more representative of each type of process. The chapter is divided into two main types of reactions, namely, hydrosilylat...

The use of protic ligands to generate metal-ligand bifunctional catalysts has proved an excellent strategy to enhance the catalytic activity in formic acid dehydrogenation. We present here synthetic routes for complexes of general formula [Ir(H)2(IPr) (PR3) (CH3CN)2]BF4 (1a-c), [Ir (8-AQ) (H)2(IPr) (PR3)]BF4 (2a-c and 3), and [Ir(IPr) (C-N) (8-AQ)H...

This article reviews the most recent advances on the study of non-classical mechanisms for the reduction of organic substrates with hydrosilanes catalyzed by transition metals. A wide variety of catalytic cycles that go beyond the classical steps described for Ojima, Chalk-Harrod and modified Chalk-Harrod mechanisms, as representative examples, hav...

This article reviews the most recent advances on the study of non-classical mechanisms for the reduction of organic substrates with hydrosilanes catalyzed by transition metals. A wide variety of catalytic cycles that go beyond the classical steps described for Ojima, Chalk-Harrod and modified Chalk-Harrod mechanisms, as representative examples, hav...

This article reviews the most recent advances on the study of non-classical mechanisms for the reductionmof organic substrates with hydrosilanes catalyzed by transition metals. A wide variety of catalytic cycles that go beyond the classical steps described for Ojima, Chalk-Harrod and modified Chalk-Harrod mechanisms, as representative examples, hav...

New Ir–IPr complexes featuring a variety of chelate ligands, some of them featuring NH moieties, were synthesized. These complexes proved to be efficient catalysts for the dehydrogenation of formic acid in DMF and H2O. The dehydrogenation rates were dependent on the nature of the ligands that accompany IPr in the coordination sphere of the metal. I...

The dehydrogenation of formic acid permits the production of hydrogen virtually free of carbon monoxide, which is a key requisite for its use in fuel cells. Moreover, HCOOH is a suitable hydrogen carrier, better in several crucial characteristics than other liquid organic hydrogen carriers, namely, low toxicity, high hydrogen content and recyclabil...

Investigations dealing with N-heterocyclic carbenes and their derivatives are usually centered on the influence that they exert by acting as catalysts, ionic liquids, or metallodrugs and consequently on their capabilities to tune the properties and reactivity of these systems. In this context, we aimed to focus on the internal molecular changes und...

The paddlewheel-shaped complex [Sb(µ-pyS)4Rh]2 (1) (pyS-: 2-S-C5H4N-) was synthesized from [Rh(pyS)(cod)]2 (cod = 1,5-cyclooctadiene) and Sb(pyS)3. Upon oxidation with ONMe3, the complex [(µ-O)Sb(µ-pyS)3Rh(κ2-pyS)]2 (2) is formed. Both 1 and 2 form dimers and feature short Rh-Sb bonds and bridging pyS ligands. 121Sb Mössbauer spectroscopy and compu...

The synthesis of a wide variety of carbamates from amines, alcohols and carbon monoxide has been achieved by means of a Rh-catalysed oxidative carbonylation reaction that uses Oxone as a stoichiometric oxidant. In-depth studies on the reaction mechanism shed light on the intimate role of Oxone in the catalytic cycle.

A variety of binuclear rhodium(i) complexes featuring two bridging dimethylphosphinate ligands ((CH3)2PO2(-)) have been prepared and tested in the alkoxycarbonylation of aromatic C-H bonds. The complex [Rh(μ-κO,O'-(CH3)2PO2)(cod)]2 has been prepared by a reaction of [Rh(μ-MeO)(cod)]2 with 2 equivalents of dimethylphosphinic acid. Binuclear complexe...

The IrIII complexes 4 and 5 bearing bis-NHC ligands (NHC = N-heterocyclic carbene) composed of one classical NR,NR NHC and one N,NR NHC donor were prepared by the reaction of the azolium/azole compounds 2I and 3Br, respectively, with [{Cp*IrCl(μ-Cl)}2] (Cp*=η5-C5Me5) in the presence of NaOAc as base. Most likely, the salts 2I and 3Br were first sel...

The Ir(i) complexes [Ir(cod)(κP,C,P'-NHO(PPh2))]PF6 and [IrCl(cod)(κC-NHO(OMe))] (cod = 1,5-cyclooctadiene, NHO(PPh2) = 1,3-bis(2-(diphenylphosphanyl)ethyl)-2-methyleneimidazoline) and NHO(OMe) = 1,3-bis(2-(methoxyethyl)-2-methyleneimidazoline), both featuring an N-heterocyclic olefin ligand (NHO), have been tested in the transfer hydrogenation rea...

The catalytic activity in the hydrosilylation of terminal alkynes by the unsaturated hydrido iridium(III) compound [IrH(κ³-hqca)(coe)] (1), which contains the rigid asymmetrical dianionic ONO pincer ligand 8-oxidoquinoline-2-carboxylate, has been studied. A range of aliphatic and aromatic 1-alkynes has been efficiently reduced using various hydrosi...

The reactivity of thiophene (T), 2-methylthiophene (2-MeT), and benzothiophene (BT) with [Ir(cod)(IPr)(L)]BF4 complexes (L = acetone (1), pyridine (2) or dimethylphenylphosphine (3); IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) in the presence of molecular hydrogen has been investigated. Under these conditions the 1,5-cyclooctadiene liga...

[{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 pre...

is used for the hydroalkynylation of imines

The study of the aggregation of small molecules in solution induced by metallophilic interactions has been traditionally performed by spectroscopic methods through identification of chemical changes in the system. Herein we demonstrate the use of SAXS (small-angle X-ray scattering) to identify structures in solution, taking advantage of the excelle...

A variety of [M(L)2(L′)2{κC,C′-bis(NHC)}]BF4 complexes (M = Rh or Ir; L = CH3CN or wingtip group; L′ = I– or CF3COO–; NHC=N-heterocyclic carbene) have been tested as pre-catalysts for the transfer hydrogenation of ketones and imines. The conversions and TOF's obtained are closely related to the nature of the ligand system and metal centre, more str...

In this chapter, recent progresses in the use of binuclear iridium complexes as catalysts for the preparation of value-added organic molecules and the catalytic cycles involved in these reactions are presented. The reactivity of these complexes toward a variety of substrates and the intermetallic cooperation mechanisms that differentiate binuclear...

The new Ir(II) complex [{Ir(μ-κCNHC,η6Dipp-IDipp)(H)}2][BF4]2 has been prepared and fully characterised. This complex acts as a catalyst for the hydroalkynylation of imines according to a unprecedented diiridium-mediated mechanism.

We describe a bis‐N‐heterocyclic carbene rhodium(III) complex, featuring two trifluoroacetato ligands, that affords a variety of α‐vinylsilanes in good yields by hydrosilylation of terminal alkynes. Selectivities around 7:1 α/β‐( E ) were reached, while the β‐( Z ) product was only marginally obtained. This example sharply contrasts with the β‐( Z...

The rhodium(I) complex [Rh(Cl)(COD)(2-methoxyphenyl-NHC-(CH2)3Si(OiPr)3)] (2a) catalyzes the solvent-free homogeneous hydrosilylation of acetophenone with HSiMe(OSiMe3)2. Kinetic studies show that 2a behaves differently to the related homogeneous catalysts [Rh(Cl)(COD)(R-NHC-(CH2)3Si(OiPr)3)] (R = 2,6-diisopropylphenyl, (2b); R = 2-methoxyethyl (2c...

Recent reports on homogeneous catalytic hydrosilylation suggest that this reaction may not always operate by the generally accepted classical catalytic cycles. Ionic and concerted outer-sphere mechanisms are broadly accepted in hydrogenation catalysis; however, they have been barely reported for catalytic hydrosilylation. Mechanistic studies hint a...

The rhodium(I) complexes [Rh(Cl)(COD)(R-NHC-(CH2)3Si(OiPr)3)] [COD=cyclooctadiene; R=2,6-diisopropylphenyl (1 a); n-butyl (1 b)] are effective catalyst precursors for the homogeneous hydrodechlorination of benzyl chloride using HSiEt3 as hydrogen source. This reaction is selective to the formation of toluene. However, in presence of a stoichiometri...

[Rh(μ-Cl)(H)2(IPr)]2 (IPr=1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) catalyzes the selective functionalization of 2-(2-thienyl)pyridine efficiently with a range of alkenes and internal alkynes. A catalytic cycle is proposed on the basis of the identification of key reaction intermediates and the study of their reactivity by NMR spectroscopy...

A cationic [Ag2(bis-NHC)2](2+) system behaves as an excellent host for Ag(+). In the solid-state variation, Ag···Ag are the only bonding interactions between host and guest, overcoming their inherent electrostatic repulsion. It represents a clear example of ligand-unsupported ("pure") argentophilicity. In solution, we also found evidence for this k...

Breaking ties: Recent reports on iridium and ruthenium homogeneous hydrosilylation catalysis point to a heterolytic activation of SiH bonds promoted by the oxophilicity of the silicon atom and the Lewis acidity of the metal center. This unusual type of mechanism opens the door to a more widespread use of catalysts that operate by an ionic or concer...

The new rhodium(I) complexes [Rh(Cl)(COD)(R-NHC-(CH2)3Si(OiPr3)3)] (R = 2,6-diisopropylphenyl (2a); n-butyl (2b)) have been synthesised and fully characterised. The study of their application as ketone hydrosilylation catalysts showed a clear N-substituent effect, 2a being the most active catalyst precursor. Complex 2a has been immobilised in the m...

Recent reports on homogeneous catalytic transformation of carbon dioxide by iridium complexes have prompted us to review the area. Progress on new iridium catalysts for carbon dioxide transformations should take into account the interaction of carbon dioxide with the iridium center, which seems to be governed by the oxidation state of iridium and t...

The β-Z selectivity in the hydrosilylation of terminal alkynes has been hitherto explained by introduction of isomerisation steps in classical mechanisms. DFT calculations and experimental observations on the system [M(I)2 {κ-C,C,O,O-(bis-NHC)}]BF4 (M=Ir (3 a), Rh (3 b); bis-NHC=methylenebis(N-2-methoxyethyl)imidazole-2-ylidene) support a new mecha...

The catalytic activation of bonds is a key step determining the outcome of the overall transformation of organic substrates. A relevant endeavor is the development of economically viable catalytic systems that efficiently convert alkanes or saturated hydrocarbons into more valuable chemicals. The focus of this chapter is on stoichiometric and catal...

The preparation of 1-(3-triisopropoxysilylpropyl)-3-(2-methoxyethyl)-imidazolium bromide or chloride salts and their reaction with [Rh(COD)(μ-OMe)]2 (COD=1,5-cyclooctadiene) to afford the corresponding [Rh(COD)(NHC)X] (X=Br, Cl; NHC=1-(3-triisopropoxysilylpropyl)-3-(2-methoxyethyl)-2-ilydene-imidazol) species is described. These new compounds were...

CO 2 als Rohstoff: Ein luft‐ und feuchtigkeitsstabiler Iridium(III)‐Katalysator vermittelt die Hydrosilylierung von CO2. Diese Reaktion verläuft effizient unter milden Bedingungen, höchstwahrscheinlich über einen Außensphären‐Mechanismus, wie theoretische Rechnungen andeuten, und führt hochselektiv zu Silylformiat.

CO(2) as feedstock: An air- and moisture-stable iridium(III) catalyst effectively promotes the hydrosilylation of CO(2) . This reaction leads to silyl formate in a highly selective manner and proceeds efficiently under mild conditions, most likely by an outer-sphere mechanism, as suggested by theoretical calculations.

A synthon for a 14-electron Ir(III) species is described. The geometrical control exerted by the ligand system over the Ir-alkenyl intermediate in hydrosilylation of terminal alkynes precludes formation of the more thermodynamically stable β-(E)-vinylsilane, thus affording the β-(Z) isomer in excellent yields.

Developments in palladium chemistry have been spurred predominantly by the outstanding application potential of this metal in catalysis. The quest for new ligands in order to modulate the catalytic activity and selectivity of the palladium center has been greatly stimulated by the discovery of N-heterocyclic carbenes as formally neutral, strongly d...

The performances of a number of RhI and IrI complexes of type [M(NHC)(COD)Cl] in the transfer hydrogenation of ketones were tested under a variety of reaction conditions, and with a variety of substrates, allowing comparison of Rh- and Ir-NHC complexes, and also comparison of the influence of the NHC ligand on catalytic performance. Notably, of the...

The use of I2/AgOAc in dichloromethane constitutes a cheap, mild, and efficient method for the selective iodination of a variety of heterocycles. In a number of cases, this method provides superior yields to other literature methods and affords iodo-functionalized heterocycles that are suitable precursors for carbene complexes.

Better together: A novel hybrid N-heterocyclic carbene (NHC) palladium complex, integrating a totally inorganic and polyanionic decatungstate unit, has been synthesized following a convergent strategy. The interplay of the Pd binding domains with the inorganic scaffold is instrumental in accessing multi-turnover catalysis in C-C crosscoupling and a...

An unsaturated seven-membered amidinium salt 7 decomposes in the presence of metal salts under basic conditions. However, 7 readily forms a Diels–Alder cycloadduct with CpH from which the RhI complexes may be prepared. Thus, structurally elaborate, sterically crowded carbene ligand complexes bearing peripheral unsaturated functionality are availabl...

Abnormal isoxazolylidene complexes, a new subclass of mesoionic complexes containing an isoxazolium-derived carbene type ligand, have been synthesised via oxidative addition and compared to structurally related mesoionic complexes by using (31)P NMR spectroscopy as a convenient probe for their donor ability and in catalytic cross-coupling reactions...

The synthesis of new functionalised 6- and 7-membered NHC (N-heterocyclic carbene) precursors bearing anisidyl or pyridine N-substituents, both symmetrically and non-symmetrically substituted is reported. Their corresponding rhodium(i) and iridium(i) complexes, M(COD)(NHC)Cl, were also prepared and characterised. The unusual Rh(iii)/Rh(i) salt, [Rh...

The rhodium complexes [Rh(NHC)(COD)Cl] and cis-[Rh(NHC)(CO)2Cl] of seven-membered N-heterocyclic carbenes (NHC) bearing aromatic N-substituents (mesityl, xylyl and o-tolyl) were synthesised, and a comparison of their steric and electronic properties with those of the analogous five- and six-membered NHC complexes was made on the basis of infrared a...

The addn. of arom. formamidines to dihaloalkanes proceeds in air under mildly basic conditions and in polar solvents to afford the corresponding amidinium salts in high yields. To demonstrate the wide scope of this methodol., several five-, six-, and seven-membered satd. N-heterocyclic amidinium salts were prepd. Some free carbenes also were isolat...

The synthesis of the novel seven-membered N-heterocyclic carbene (NHC) 1,3-dicyclohexyl-1,3- diazepan-2-ylidene (3) and its 5,6-dioxolane derivative 4 is reported and their coordination chemistry with Rh(I), Ir(I), and Pt(0) discussed. The M(cod)(3)Cl, where M ) Rh and Ir, complexes display a high rotation barrier at room temperature about the M-CN...

The synthesis of the novel seven-membered N-heterocyclic carbene (NHC) 1,3-dicyclohexyl-1,3- diazepan-2-ylidene (3) and its 5,6-dioxolane derivative 4 is reported and their coordination chemistry with Rh(I), Ir(I), and Pt(0) discussed. The M(cod)(3)Cl, where M ) Rh and Ir, complexes display a high rotation barrier at room temperature about the M-CN...

The rhenium complex fac-[ReOCl 3 L] [1; L = 1,3-bis(diphenylphosphanyloxy)propane] was prepared by reacting L with [ReO-Cl 3 (AsPh 3) 2 ]. Refluxing complex 1 in ethanol gave [ReOCl 2 (OEt)L] (2), which X-ray crystallography showed to have an octahedral rhenium environment and an Re–O–Et fragment of unusual linearity. The paramagnetic chlorocomplex...

The rhenium complex fac-[ReOCl3L] [1; L = 1,3-bis(diphenylphosphanyloxy)propane] was prepared by reacting L with [ReOCl3(AsPh3)2]. Refluxing complex 1 in ethanol gave [ReOCl2(OEt)L] (2), which X-ray crystallography showed to have an octahedral rhenium environment and an Re–O–Et fragment of unusual linearity. The paramagnetic chlorocomplexes mer-[Re...