Square-planar d(8)-ML4 complexes might display subtle but noticeable local Lewis acidic sites in axial direction the valence shell of metal atom. These charge depletion provide electronic prerequisites to establish weakly attractive 3c-2e M⋅⋅⋅H-C agostic interactions, contrast earlier assumptions. Furthermore, we show that use sign (1)H NMR shifts as major criterion classify interactions (agostic) or repulsive (anagostic) can be dubious. We therefore suggest a new characterization method...

Although benzene and borazine are isoelectronic isostructural, they have very different electronic structures, mainly due to the polar nature of B-N bond. Herein, we present an experimental study charge density distribution obtained from multipole model formalism Hirshfeld atom refinement (HAR) based on high-resolution X-ray diffraction data B3N3H6 (1) B,B',B″-trichloroborazine (2) crystals. These compared those HAR for (4) 1,3,5-trichlorobenzene (5) further with values functional theory...

Experimental and theoretical charge density studies molecular orbital analyses suggest that the complexes [Cp2Ti(PMe3)SiH2Ph2] (1) [Cp2Ti(PMe3)SiHCl3] (2) display virtually same electronic structures. No evidence for a significant interligand hypervalent interaction could be identified 2. A bonding concept transition-metal hydrosilane aims to identify true key parameters selective activation of individual MSi SiH bonds. As service our authors readers, this journal provides supporting...

Agostic hydrogen atoms in planar d(8) transition metal complexes display a remarkable wide range of chemical shifts from +5 to -10 ppm the proton NMR spectra. It is therefore surprising that simple recipe can be elaborated predict influence local electronic structure atom on shielding coordinating protons: In cases where agostic pointing Lewis acidic center at (1)H signal shifted upfield relative scenario opposing charge concentration metal. To trace physical origin this empirical...

Abstract Square‐planar d 8 ‐ML 4 complexes might display subtle but noticeable local Lewis acidic sites in axial direction the valence shell of metal atom. These charge depletion provide electronic prerequisites to establish weakly attractive 3c–2e M⋅⋅⋅HC agostic interactions, contrast earlier assumptions. Furthermore, we show that use sign 1 H NMR shifts as major criterion classify interactions (agostic) or repulsive (anagostic) can be dubious. We therefore suggest a new characterization...

Abstract interactions are unique dispersive that important for biological systems and materials, but the study of this interaction is not trivial. It well‐known density functional theory (DFT) does describe these correctly only with empirical dispersion corrections, it produces accurate energies. Moreover, little known about error in electron (). Non‐Covalent Interaction method (NCI) has been used to analyze stacking from density. However, interactions, information can be extracted quite...

Abstract In general, it is assumed that the reaction between silanes and late transition metal fragments yields silyl hydride species as oxidative addition products. However, silane complex Ni( i Pr 2 Im) (SiHMePh ) ( Im = 1, 3‐diisopropylimidazolin‐2‐ylidene) 3a ), might represent one of rare systems where a stable η ‐(Si–H)Ni intermediate process has been isolated. Indeed, characterized by an acute [ang]Si–Ni–H angle 62.0(2)°, rather short Si–H bond length 1.992(6) Å displays...

Chemical-biological efforts to increase the diversity of duclauxin (

The fundamental study of the biogenetic origin natural products has always been limited from experimental point view because proposed reaction mechanisms have only supported on molecular structures reagents and products. In a seminal contribution, Ortega Maldonado (Ortega, A.; Maldonado, E. Heterocycles, 1989, 29, 635-638.) described an experiment relevant for development theory sesquiterpene lactones. They were able to obtain one-pot transformation pseudoguaianolide sesquiterpenic lactone...

Abstract We will outline that the sign and magnitude of J (Si,H) coupling constants provide a highly sensitive tool to measure extent Si−H bond activation in nonclassical silane complexes. Up now, this structure–property relationship was obscured by erroneous determinations literature. These new findings also help identify salient control parameters process

An efficient method to obtain chiral 1,2-disubstituted ferrocenyl ligands has been developed. The introduction of planar chirality was accomplished by using 2-thiazoline as an ortho-directing lithiation group, and moreover, these kinds possess a central from the amino alcohol used in their synthesis. X-ray analysis DFT calculations confirmed diastereoselectivity ortho-lithiation configuration chirality. ability new bidentate [N,S]-ferrocene act Pd-catalyzed asymmetric allylic alkylation also...

We outline in this combined experimental and theoretical NMR study that sign magnitude of J(Si,H) coupling constants provide reliable indicators to evaluate the extent oxidative addition Si–H bonds hydrosilane complexes. In combination with electron density studies MO analyses a simple structure–property relationship emerges: positive are observed cases where M → L π-back-donation (M = transition metal; ligand) dominates. The corresponding complexes located close terminus respective...

In recent years interest in the development of protocols that facilitate oxidative addition gold to access mild cross-coupling processes mediated by this metal has increased. context, we report herein ascorbic acid, a natural and readily accessible antioxidant, can be used accelerate aryldiazonium chlorides onto AuI . The aryl-AuIII species generated way, been prepare 3-arylindoles one-pot protocol starting from anilines para-, meta-, ortho- substituted chlorides. mechanism underlying...

We describe, herein, arylative carbocyclization of alkynes catalyzed by gold. In this process, Au(I) is oxidized to Au(III) with aryldiazonium tetrafluoroborates following a photosensitizer-free and irradiation-free protocol. Ascorbic acid acts as radical initiator, generating aryl radicals. According DFT calculations, these radicals are added Au(I), leading Au(II) species that further the assistance tetrafluoroborate anion. The overall process very energetically favorable, transforming...

Two mechanisms have been proposed in the literature to explain formation of skeleton terrecyclic acid from farnesyl diphosphate. Both satisfy experimental data obtained using isotopic labeling, but computational results at mPW1B95/6-31+G(d,p) level theory allow differentiation between them. While one is basically a carbocation cascade, other requires several steps that imply high energetic demands. Specifically, there [1,3] hydride shift approximately 100 kcal/mol making this unlikely. The...

Torquoselectivity has explained diasteromeric preferences of a number electrocyclic ring openings. The quantum theory atoms in molecules (QTAIM), the electron localizability indicator (ELI-D), and interacting (IQA) energy partition method are used to evaluate qualitatively quantitatively atomic interactions behind torquoselectivity series 3-substituted cyclobutenes. ELI-D topology IQA energies show that interaction between distal terminus carbon atom cyclobutene (C4) with substituent at C3...

The induced current density ( J r )) provides useful information about the electronic structure of molecules under a magnetic field B ). However, analysis its topology is cumbersome because vectorial nature. We show that tropicity (direction rotation) and strength can be compressed in triple product ⋅ ∇ × ) (tp scalar field. tp has clear similarities to Laplacian electron density. Additionally, aromatic antiaromatic compounds notoriously different. vorticity helpful define circulation...

The normal and reverse Perlin effect is usually explained by the redistribution of electron density produced hyperconjugative mechanisms, which increases population within axial or equatorial proton in effect, respectively. Here an alternative explanation for presented on basis topology induced current density, directly determines nuclear magnetic shielding. Current densities around C-H bond critical point intra-atomic interatomic contributions to shielding explain observed effect. balance...

Abstract The kinetic energy is the center of a controversy between two opposite points view about its role in formation chemical bond. One school states that lowering associated with electron delocalization key stabilization mechanism covalent bonding. In contrast, holds bond formed by decrease potential due to concentration density within binding region. this work, topographic analysis Hamiltonian Kinetic Energy Density (KED) and laplacian presented gain more insight into interactions. This...

Abstract The induced current density ( J r )) vector field has been extensively used as a criterion of aromaticity and electron delocalization. However, the selection direction perturbing magnetic B ) is arbitrary in case three‐dimensional delocalization/aromaticity could be ambiguous. also recently received some criticism an index. We propose Trace Vorticity Current Density tensor (TVCD) scalar more suitable quantity for evaluation delocalization systems. It does not depend on orientation...

Abstract Copper(I) complexes (CICs) are of great interest due to their applications as redox mediators and molecular switches. CICs present drastic geometrical change in excited states, which interferes with luminescence properties. The photophysical process has been extensively studied by several time‐resolved methods gain an understanding the dynamics mechanism torsion, explained terms a Jahn–Teller effect. Here, we propose alternative explanation for photoinduced structural CICs, based on...

We present the use of interaction between aromatic rings as main tool in organization coordination compounds a crystal.

Allenes (carbodicarbenes) and [3]cumulenes are linear carbon chains that can be bent when the terminal group has a strong carbene nature. This bending quite pronounced in allenes but not [3]cumulenes. In this study, how N-heterocyclic or cyclic (alkyl)(amino) (NHC CAAC, respectively) groups modify structure of [n]cumulenes been analyzed. A low π acidity affects linearity [2n]cumulenes. Indeed, it found NHC [4]cumulene is extremely bent, contrary to classical [4]cumulenes. The predicted...

Knowing the conformational properties of 1(10),4-cyclodecadiene γ-lactones is important because biogenetic and evolutionary implications on different groups sesquiterpene lactones. Despite their importance, there are no physicochemical data dynamic potential energy surface associated with changes cyclodecadiene ring. Fischer's theory origin ambrosanolides helenanolides has support in results presented since conformers that yield two lactones coexist solution as demonstrated by NMR...