The influence of electronic ligand properties on the catalyst performance in the rhodiumcatalyzed hydroformylation of alkenes has been investigated. Two bidentate phosphorus amidite and phosphinite ligands have been synthesized: 1,1′-biphenyl-2,2′-diyl-bis(dipyrrolylphosphoramidite) (3) and 1,1′-biphenyl-2,2′-diyloxy-bis(diphenylphosphinite) (4). Their monodentate analogues have also been studied: phenyldipyrrolylphosphoramidite (1) and phenyl diphenylphosphinite (2). These two sets of ligands have very similar steric properties but the amidites are much stronger π-acceptor ligands. Spectroscopic studies showed that under hydroformylation reaction conditions the monodentate ligands 1 and 2 form mixtures of HRhL 2 (CO) 2 and HRhL 3 (CO) complexes depending on the ligand and rhodium concentrations and the carbon monoxide pressure. Depending on the reaction conditions, the bidentate ligands 3 and 4 form mixtures of HRh(L∩L)(CO) 2 and HRh(L∩L)(L∩L′)(CO), where L∩L′ functions as a monodentate. All ligands have been tested in the hydroformylation reaction of oct-1-ene. A high π-acidity of the ligand resulted in a high rate of hydroformylation. The monodentate ligands 1 and 2 showed moderate selectivity for the linear aldehyde. The catalyst formed with the bidentate phosphorus amidite ligand 3 revealed high regioselectivity for the linear aldehyde (ratio l/b ) ∼100) at a high rate together with a moderate selectivity for isomerization (∼7%). Deuterioformylation experiments of 1-hexene showed that the hydride (deuteride) migration is reversible in the hydroformylation system formed by 3. Surprisingly, both the linear rhodium-alkyl and the branched rhodium-alkyl complex undergo β-hydride elimination. Furthermore, the 2-hexylrhodium intermediate regenerates more often monodeuterated 1-hexene than 2-hexene. The rhodium hydride species formed this way reacts relatively slowly with the excess of D 2 and as a result large amounts of monodeuterated heptanal (40% D 1 vs 60% D 2 ) and monodeuterated 1-hexene are formed. At higher conversions the latter gives trisdeuterated heptanal as well as bisdeuterated heptanal.

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Even though there are many photocurable compositions that are cured by cationic photopolymerization mechanisms, UV curing generally consists of the formation of cross-linking covalent bonds between a resin and monomers via a photoinitiated free radical polymerization reaction, obtaining a three-dimensional polymer network. One of its many applications is in the refinish coatings market, where putties, primers and clear coats can be cured faster and more efficiently than with traditional curing. All these products contain the same essential components, which are resin, monomers and photoinitiators, the latter being the source of free radicals. They may also include additives used to achieve a certain consistency, but always taking into account the avoidance of damage to the UV curing—for example, by removing light from the innermost layers. Surface curing also has its challenges since it can be easily inhibited by oxygen, although this can be solved by adding scavengers such as amines or thiols, able to react with the otherwise inactive peroxy radicals and continue the propagation of the polymerization reaction. In this review article, we cover a broad analysis from the organic point of view to the industrial applications of this line of research, with a wide current and future range of uses.

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Hydrogenation of polyalphaolefins (PAOs) is an industrial process catalyzed by supported precious metals. In this regard, halloysite (Hal) clay has been proven as an efficient support for the immobilization of Pd nanoparticles and development of high-performance catalysts under mild reaction condition. In this research, the effect of Hal hydrophobicity on the PAO hydrofinishing efficiency is studied. In this line, cetrimonium bromide (CTAB) was used for adjusting the hydrophobicity of halloysite surface. Three catalysts, Hal/Pd, Hal/Pd/CTAB, and Hal/CTAB/Pd, were fabricated by palladation of Hal, treating palladated Hal with CTAB and palladation of CTAB-treated Hal, respectively. The catalysts were characterized, and their activity for the hydrogenation of PAO was appraised. Moreover, a molecular simulation approach was employed to survey the effect of surface hydrophobicity of Hal on the alkene hydrogenation energy diagram and the steric maps of the main catalytic stages. Both experimental and computational studies approved that the presence of CTAB detracts the activity of the catalyst. Moreover, the order of introduction of Pd and CTAB affects the content of incorporated CTAB and Pd and Pd particle size, and the order of catalysts activity was as follows:

The chiral ligand (1R,2S,5R)-1-((diphenylphosphino)methyl)-2-isopropyl-5-methylcyclohexanethiol (4) has been prepared from low-cost commercial (−)-menthone in a three-step enantioselective synthesis. Oxidative addition of 2 equiv of this phosphinothiol ligand to [Pd0(PPh3)4] gave the enantiopure bis(phosphinothiolate)palladium(II) complex 5, which only exists as the trans-P,P geometrical isomer, in both the solid state and solution, owing to the preference of the chelate rings to adopt the λ conformation in which the position of the menthane ring does not allow a conformation of the phenyl groups compatible with the more sterically hindered cis geometry. These stereoelectronic coordination preferences of the chiral phosphinothiolate ligand have been confirmed by the structure of the analogous Pt(II) complex 6, which also exhibits the trans-P,P geometry exclusively, both in the solid state and in solution. Crystals of 5·1/2CH2Cl2 and 6·1/2CH2Cl2 are isomorphic, belonging to the monoclinic crystal system C2. Both chiral structures show mononuclear square-planar trans complexes with locked λ chelate ring conformations. Compound 6 represents the first example of a structurally characterized mononuclear bis(phosphinothiolate)platinum(II) complex. Addition of 1 equiv of ligand 4 to a solution of [PdCl2(PPh3)2] gave the less sterically hindered complex chloro(phosphinothiolate)(triphenylphosphine)palladium(II) (7), which exhibits the expected cis−trans equilibrium in solution, but strongly displaced to the more sterically stable trans isomer.

The presence of a stereogenic carbon centre (R or S) in the racemic ligand 1-(diphenylphosphanyl)propane-2-thiol induces a conformational preference (λ or δ) in the five-membered chelate ring of its 2:1 and 2:2 coordination compounds with Ni II : the mononuclear trans-[Ni{SCH(CH 3 )CH 2 PPh 2 -P,S} 2 ] (1) and the binuclear trans-[Ni{µ-SCH(CH 3 )CH 2 PPh 2 -P,S}(Cl)] 2 (2). Both complexes exist as mixtures of two diastereomers: racemic-trans (R λ , R λ and S δ , S δ ) and meso-trans