Marta Marín-Luna

Cooperativity in Tetrel Bonds

A theoretical study of the cooperativity in linear chains of (H3SiCN)n and (H3SiNC)n complexes connected by tetrel bonds has been carried out by means of MP2 and CCSD(T) computational methods. In all cases, a favorable cooperativity is observed, especially in some of the largest linear chains of (H3SiNC)n, where the effect is so large that the SiH3 group is almost equidistant to the two surrounding CN groups and it becomes planar. In addition, the combination of tetrel bonds with other weak interactions (halogen, chalcogen, pnicogen, triel, beryllium, lithium, and hydrogen bond) has been explored using ternary complexes, (H3SiCN)2:XY and (H3SiNC)2:XY. In all cases, positive cooperativity is obtained, especially in the (H3SiNC)2:ClF and (H3SiNC)2:SHF ternary complexes, where, respectively, halogen and chalcogen shared complexes are formed.

[4 + 2] Cycloaddition Reaction of C-Aryl Ketenimines with PTAD as a Synthetic Equivalent of Dinitrogen. Synthesis of Triazolocinnolines and Cinnolines

C,C,N-Triaryl ketenimines and C-alkyl-C,N-diaryl ketenimines react with 2 equiv of PTAD to provide 1,2,4-triazolo[1,2-a]cinnolines with a pendant triazolidindione group by means of a Diels-Alder/ene sequence. The treatment of such adducts with potassium hydroxide affords 3-aminocinnolines.

Interplay between Beryllium Bonds and Anion-π Interactions in BeR2:C6X6:Y- Complexes (R = H, F and Cl, X = H and F, and Y = Cl and Br).

A theoretical study of the beryllium bonds in BeR2:C6X6 (R = H, F, Cl and X = H and F) has been carried out by means of MP2/aug′-cc-pVDZ computational methods. In addition, the ternary complexes BeR2:C6X6:Y− (Y = Cl and Br) have been analyzed. Geometric, energetic and electronic aspects of the complexes have been taken into account. All the parameters analyzed provide a clear indication of favorable cooperativity in both interactions observed, beryllium bond and aromatic ring:anion interaction.

The Outer-Sphere Mechanism of Nitrene Transfer onto Gold(I) Alkyne Complexes

The recently developed nitrene transfer reaction onto gold‐activated alkynes provides a route to safe and accessible synthons of α‐diazo imides. This reaction is rather unique in that it requires AuI in catalytic amounts; however, this promiscuous metal is only used to activate the alkyne moiety. After such activation is obtained, the nitrene‐transfer process occurs through an outer‐sphere mechanism, in which the metal acts only as a spectator. Density functional theory was applied to elucidate this peculiar reaction and to provide a mechanistic explanation for the experimentally observed isomers at the double bond and imine sites.

A theoretical NMR study of selected benzazoles: comparison of GIPAW and GIAO-PCM (DMSO) calculations

This paper compares the absolute shieldings obtained by gauge‐including‐projected‐augmented‐wave (GIPAW) to those obtained by gauge‐invariant atomic orbital/Becke, 3‐parameter, Lee‐Yang‐Parr (GIAO/B3LYP)/6–311++G(d,p)‐polarizable continuum model (PCM, dimethyl sulfoxide) for nine benzazoles (benzimidazoles, indazoles, and benzotriazoles) recorded in the solid‐state. Three nuclei were explored, 13C, 15N, and 19F, and the gauge‐including‐projected‐augmented‐wave approach only proved better for 15N MAS NMR.

[MoO2]2+-Mediated Oxygen Atom Transfer via an Unusual Lewis Acid Mechanism

Density functional theory is applied to the study of the oxygen atom transfer reaction from sulfoxide (DMSO) to phosphine (PMe3) catalyzed by the [MoO2]2+ active core. In this work, two fundamentally different roles are explored for this dioxometal complex in the first step of the catalytic cycle: as an oxidizing agent and as a Lewis acid. The latter turns out to be the favored pathway for the oxygen atom transfer. This finding may have more general implications for similar reactions catalyzed by the same [MoO2]2+ core.

Accessing polysubstituted oxazolidines, pyrrolidines and imidazolidines by regioselective [3 + 2] annulations of ketenimines with donor–acceptor oxiranes and aziridines

Efficient [3 + 2] annulations of N-aryl-C,C-diphenyl ketenimines with metallo-carbonyl and metallo-azomethine ylides, generated via the respective Yb(OTf)3 and Y(OTf)3 promoted carbon–carbon bond heterolysis of donor–acceptor oxiranes and aziridines, have been accomplished. These reactions proceeded under mild conditions and supplied a general methodology for the regioselective construction of structurally complex oxazolidines and pyrrolidines. Moreover, heating neat mixtures of N-aryl-C,C-diphenyl ketenimines and diethyl aziridine-2,3-dicarboxylates led to imidazolidine derivatives. A computational study concluded in stepwise mechanisms for these [3 + 2] annulations, also shedding light on their regioselectivity, concerning which of the two cumulated double bonds of the ketenimine becomes involved in the reaction with the ylide.

Mechanism of the Molybdenum-Mediated Cadogan Reaction

Oxygen atom transfer reactions are receiving increasing attention because they bring about paramount transformations in the current biomass processing industry. Significant efforts have therefore been made lately in the development of efficient and scalable methods to deoxygenate organic compounds. One recent alternative involves the modification of the Cadogan reaction in which a Mo(VI) core catalyzes the reduction of o-nitrostyrene derivatives to indoles in the presence of PPh3. We have used density functional theory calculations to perform a comprehensive mechanistic study on this transformation, in which we find two clearly defined stages: an associative path from the nitro to the nitroso compound, characterized by the reduction of the catalyst in the first step, and a peculiar mechanism involving oxazaphosphiridine and nitrene intermediates leading to an indole product, where the metal catalyst does not participate.