An Experimental and Theoretical Investigation into [2π + 2π] Cycloaddition Reactions Catalyzed by a Cationic Cobalt(I) Complex Containing a Strong-Field PCP Pincer Ligand.

In the past decade, metal-catalyzed [2π + 2π] cycloaddition reactions have gained significant momentum for the synthesis of substituted cyclobutanes and bicyclo[3.2.0]-heptanes.

N Dissociation vs Reversible 1,2-Methyl Migration in PCP Cobalt(I) Complexes in the Stereoselective Isomerization () of Allyl Ethers.

With growing efforts pushing toward sustainable catalysis, using earth-abundant metals has become increasingly important. Here, we present the first examples of cobalt PCP pincer complexes that demonstrate dual stereoselectivity for allyl ether isomerization. While the cationic cobalt complex [((PCP)Co)-μ-N][BAr ] () mainly favors the -isomer of the enol ether, the corresponding methyl complex [(PCP)CoMe] () mostly gives the -isomer.

Direct observation of arene⋯sulphur dioxide interaction: role of metal ions in electronic modulation for binding and activation.

In the quest to understand biologically relevant interactions of environmentally detrimental SO with host molecules to modulate the electronic properties of the binding sites, we have directly observed the lone pair⋯π interaction between the aromatic ring and nucleophilic O of SO (3.11 Å), for the first time to the best of our knowledge, in addition to the interaction between electrophilic S of SO and metal-bound thiolate (2.63 Å).

A Neutral PCP Co(I)-Me Pincer Complex as a Catalyst for -Allylic Isomerization with a Broad Substrate Scope.

Earth-abundant-metal catalyzed double bond transposition offers a sustainable and atom-economical route toward the synthesis of internal alkenes. With an emphasis specifically on internal olefins and ethers, the isomerization of allylic amines has been particularly under represented in the literature. Herein, we report an efficient methodology for the selective isomerization of -allylic organic compounds, including amines, amides, and imines.

Late-stage Ligand Modification After Coordination Strengthens Stereoselectively Self-Assembled Hemiaminal Ether Complexes.

Fragile hemiaminal ether linkages present in the backbone of koneramines (L OR'), tridentate ligands, bound to copper(II) in stereoselectively self-assembled syn-[Cu(L OR')X ] complexes were transformed into sturdy methylene linkages to make corresponding rac-[Cu(L H)Cl ] complexes by late-stage ligand modification after coordination with the retention of coordination sphere. The generality of stereoselective self-assembly of koneramine complexes is shown by utilising a number of metal ions, anions, amines, alcohols and thiols with complete characterisations.

Triazine based eccentric Piedfort units towards a single source hydrogen bonded network.

Herein we report a hydrogen-bonded three-dimensional network originating from a single source precursor, -triisopropylaminotriazine, that is both a donor and an acceptor of hydrogen bonds. The symmetric design allowed the formation of intermolecular hydrogen bonds leading to helices in all three directions. The eccentric Piedfort units present in the framework with a distance of 8.

Mechanism of Evolution of Koneramine Complexes from One-Pot Reactions: Snapshots of Intermediates Offer Facile Routes to New Dipicolylamines.

Koneramines (L OR', R=Ph or Ts; R'=Me, iPr) and their complexes were found to emerge from the system of pyridine-2-carboxaldehyde and N-phenyl/tosylethylenediamine when a primary or secondary alcohol was used as solvent. Imidazolidinylpyridines (L , R=Ph or Ts) became major emergents whereas hemi-aminals (L OH, R=Ph or Ts) are minor emergents of the system when tertiary butanol was used as the solvent; the bulky tertiary butyl group prevented the addition of alcohol to the iminium ion that diverted the equilibrium towards imidazolidinylpyridines. By playing with the components of the reaction mixture, crystals of the metastable intermediates bound to copper(II) and/or zinc(II) were obtained and the structures were determined by X-ray diffraction analysis.

Synthetic [NiFe] models with a fluxional CO ligand.

A [NiFe] complex [(dppe)Ni(pdt)FeCp*(CO)] was isolated and characterized as two isomers [1(CO)] and [1'(CO)]. Heating the solution of [1(CO)] allowed it to convert into [1'(CO)]. The one-electron oxidation of [1'(CO)] to [1'(CO)] induced fluxional CO movement providing [1(CO)].

Multicomponent One-pot Reactions Towards the Synthesis of Stereoisomers of Dipicolylamine Complexes.

Reported are multi-component one-pot syntheses of chiral complexes [M(L(R) OR')Cl2 ] or [M(L(R) SR')Cl2 ] from the mixture of an N-substituted ethylenediamine, pyridine-2-carboxaldehyde, a primary alcohol or thiol and MCl2 utilizing in-situ formed cyclized Schiff bases where a C-O bond, two stereocenters, and three C-N bonds are formed (M=Zn, Cu, Ni, Cd; R=Et, Ph; R'=Me, Et, nPr, nBu). Tridentate ligands L(R) OR' and L(R) SR' comprise two chiral centers and a hemiaminal ether or hemiaminal thioether moiety on the dipicolylamine skeleton. Syn-[Zn(L(Ph) OMe)Cl2 ] precipitates out readily from the reaction mixture as a major product whereas anti-[Zn(L(Ph) OMe)Cl2 ] stays in solution as minor product.