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Solvent effects on 31P‐NMR parameters for triphenylphosphine oxide and triphenylphosphine in chloroform have been extensively investigated by testing different solvation models. The solvent is described implicitly, mixed implicitly/explicitly, and using full explicit models. Polarizable continuum model (PCM), molecular dynamic (MD) simulations, and hybrid quantum mechanics/molecular mechanics (QM/MM) calculations are used to disclose the effects of solute/solvent interactions and, more generally, the role of the embedding in NMR simulations. The results show the beneficial effect of carrying out QM/MM optimizations on top of geometries directly extracted from classical MD simulations, used to ensure representative conformational sampling. The nuclear shielding convergence has been tested against a different number of snapshots and with the inclusion of solvent shells into the QM region. An automated MD//QM/MM//GIAO protocol, implemented in the COBRAMM package, is here proposed and tested on trimethyl phosphite showing that our approach boosts the convergence of nuclear shielding satisfactorily. The present work aims to be a stepping‐stone to assess proper QM/MM computational strategies in simulating chemical shifts in non‐homogeneous systems like supramolecular and biological systems. [ABSTRACT FROM AUTHOR]

The reaction of Ti(NMe2)4 with the salan ligand precursor H2N2O2H2 led to the formation of [(L*)Ti(NHMe2)2] (L*=N2O24−) that forms [(H2N2O2)TiCl2] upon reaction with two equiv. of Me3SiCl. [(L*)Ti(py)2] was obtained from the reaction of [Ti(NtBu)Cl2(py)3] with the sodium salt H2N2O2Na2. Treatment of [(L*)Ti(NHMe2)2] with two equiv. of tBuNCO led to the insertion of the isocyanate molecules into the Ti−Nsalan bonds with the formation of [{L*(N(tBu)CO)2}Ti]. Conversely, the reaction of [(H2N2O2)Ti(OiPr)2] with two equiv. of tBuNCO led to the insertion of one isocyanate molecule into a Ti−Nsalan bond with the formation of [{(HN2O2)(N(tBu)CO)}Ti(OiPr)]. Computational studies were performed to gain insight into the reactivity of isocyanates with salan‐based Ti(IV) complexes. [ABSTRACT FROM AUTHOR]

Achieving the selective modification of symmetric poly‐hydroxylated compounds presents a significant challenge due to the presence of identical active sites. Herein, we address this challenge through the design of a ternary catalytic system that includes a photoredox catalyst, a hydrogen atom transfer promotor and a carbonation catalyst. This catalytic system enables the reversible carbonation of acyclic polyols under CO2 atmosphere, which modulates the reactivity of its distinct C−H bonds toward hydrogen atom transfers. An exquisite selectivity for the monoalkylation is achieved in a variety of unprotected light polyols, yielding valuable building blocks in short reaction times. Mechanistic and computational studies demonstrate that the formation of an intramolecular hydrogen bond between the transient carbonate and the free alcohol is pivotal for the kinetic and thermodynamic activation of a specific alcohol. [ABSTRACT FROM AUTHOR]

Achieving the selective modification of symmetric poly‐hydroxylated compounds presents a significant challenge due to the presence of identical active sites. Herein, we address this challenge through the design of a ternary catalytic system that includes a photoredox catalyst, a hydrogen atom transfer promotor and a carbonation catalyst. This catalytic system enables the reversible carbonation of acyclic polyols under CO2 atmosphere, which modulates the reactivity of its distinct C−H bonds toward hydrogen atom transfers. An exquisite selectivity for the monoalkylation is achieved in a variety of unprotected light polyols, yielding valuable building blocks in short reaction times. Mechanistic and computational studies demonstrate that the formation of an intramolecular hydrogen bond between the transient carbonate and the free alcohol is pivotal for the kinetic and thermodynamic activation of a specific alcohol. [ABSTRACT FROM AUTHOR]

Achieving the selective modification of symmetric poly‐hydroxylated compounds presents a significant challenge due to the presence of identical active sites. Herein, we address this challenge through the design of a ternary catalytic system that includes a photoredox catalyst, a hydrogen atom transfer promotor and a carbonation catalyst. This catalytic system enables the reversible carbonation of acyclic polyols under CO2 atmosphere, which modulates the reactivity of its distinct C−H bonds toward hydrogen atom transfers. An exquisite selectivity for the monoalkylation is achieved in a variety of unprotected light polyols, yielding valuable building blocks in short reaction times. Mechanistic and computational studies demonstrate that the formation of an intramolecular hydrogen bond between the transient carbonate and the free alcohol is pivotal for the kinetic and thermodynamic activation of a specific alcohol. [ABSTRACT FROM AUTHOR]

Achieving the selective modification of symmetric poly‐hydroxylated compounds presents a significant challenge due to the presence of identical active sites. Herein, we address this challenge through the design of a ternary catalytic system that includes a photoredox catalyst, a hydrogen atom transfer promotor and a carbonation catalyst. This catalytic system enables the reversible carbonation of acyclic polyols under CO2 atmosphere, which modulates the reactivity of its distinct C−H bonds toward hydrogen atom transfers. An exquisite selectivity for the monoalkylation is achieved in a variety of unprotected light polyols, yielding valuable building blocks in short reaction times. Mechanistic and computational studies demonstrate that the formation of an intramolecular hydrogen bond between the transient carbonate and the free alcohol is pivotal for the kinetic and thermodynamic activation of a specific alcohol. [ABSTRACT FROM AUTHOR]

Solvent effects on 31 P-NMR parameters for triphenylphosphine oxide and triphenylphosphine in chloroform have been extensively investigated by testing different solvation models. The solvent is described implicitly, mixed implicitly/explicitly, and using full explicit models. Polarizable continuum model (PCM), molecular dynamic (MD) simulations, and hybrid quantum mechanics/molecular mechanics (QM/MM) calculations are used to disclose the effects of solute/solvent interactions and, more generally, the role of the embedding in NMR simulations. The results show the beneficial effect of carrying out QM/MM optimizations on top of geometries directly extracted from classical MD simulations, used to ensure representative conformational sampling. The nuclear shielding convergence has been tested against a different number of snapshots and with the inclusion of solvent shells into the QM region. An automated MD//QM/MM//GIAO protocol, implemented in the COBRAMM package, is here proposed and tested on trimethyl phosphite showing that our approach boosts the convergence of nuclear shielding satisfactorily. The present work aims to be a stepping-stone to assess proper QM/MM computational strategies in simulating chemical shifts in non-homogeneous systems like supramolecular and biological systems., (© 2024 Wiley Periodicals LLC.)

The reaction of Ti(NMe 2 ) 4 with the salan ligand precursor H 2 N 2 O 2 H 2 led to the formation of [(L*)Ti(NHMe 2 ) 2 ] (L*=N 2 O 2 4- ) that forms [(H 2 N 2 O 2 )TiCl 2 ] upon reaction with two equiv. of Me 3 SiCl. [(L*)Ti(py) 2 ] was obtained from the reaction of [Ti(N t Bu)Cl 2 (py) 3 ] with the sodium salt H 2 N 2 O 2 Na 2 . Treatment of [(L*)Ti(NHMe 2 ) 2 ] with two equiv. of t BuNCO led to the insertion of the isocyanate molecules into the Ti-N salan bonds with the formation of [{L*(N( t Bu)CO) 2 }Ti]. Conversely, the reaction of [(H 2 N 2 O 2 )Ti(O i Pr) 2 ] with two equiv. of t BuNCO led to the insertion of one isocyanate molecule into a Ti-N salan bond with the formation of [{(HN 2 O 2 )(N( t Bu)CO)}Ti(O i Pr)]. Computational studies were performed to gain insight into the reactivity of isocyanates with salan-based Ti(IV) complexes., (© 2024 Wiley-VCH GmbH.)

Achieving the selective modification of symmetric poly-hydroxylated compounds presents a significant challenge due to the presence of identical active sites. Herein, we address this challenge through the design of a ternary catalytic system that includes a photoredox catalyst, a hydrogen atom transfer promotor and a carbonation catalyst. This catalytic system enables the reversible carbonation of acyclic polyols under CO 2 atmosphere, which modulates the reactivity of its distinct C-H bonds toward hydrogen atom transfers. An exquisite selectivity for the monoalkylation is achieved in a variety of unprotected light polyols, yielding valuable building blocks in short reaction times. Mechanistic and computational studies demonstrate that the formation of an intramolecular hydrogen bond between the transient carbonate and the free alcohol is pivotal for the kinetic and thermodynamic activation of a specific alcohol., (© 2023 Wiley-VCH GmbH.)