Cooperativity in Noncovalent Interactions.

Confined nanospaces in metallocages: guest molecules, weakly encapsulated anions, and catalyst sequestration.

The Heck–Mizoroki cross-coupling reaction is an important part of the synthetic chemist's toolbox, and it has been applied to a huge variety of different substrates. In contrast, the mechanism of the process is much less studied, and consequently less understood. There have been numerous studies reported over recent years, both experimental and theoretical, aimed at uncovering the inner working of this palladium-mediated coupling process. This perspective aims to review and compare these works and to provide an up-to-date view of this reaction.

http://www.uwindsor.ca/users/j/jlichaa/reference.nsf/0/10ff8b04ff3a317885256d88005720f6/$FILE/obc-2007-5-31%20Heck%20mech.pdf

The Heck-Mizoroki cross-coupling reaction: a mechanistic perspective.

The comprehensive investigation reported herein provides compelling evidence that anion−π interactions are the main driving force in the formation of self-assembled Fe(II)-templated metallacycles with bptz [3,6-bis(2-pyridyl)-1,2,4,5-tetrazine] in high yields. It was demonstrated by X-ray crystallography, 1H NMR, solution and solid-state MAS 19F NMR spectroscopies, CV and MS studies that the anions [X]− = [BF4]−, [ClO4]− and the anions [Y]− = [SbF6]−, [AsF6]−, [PF6]− template molecular squares [Fe4(bptz)4(CH3CN)8][X]8 and pentagons [Fe5(bptz)5(CH3CN)10][Y]10, respectively. The X-ray structures of [{Fe4(bptz)4(CH3CN)8}⊂BF4][BF4]7 and [{Fe5(bptz)5(CH3CN)10}⊂2SbF6][SbF6]8 revealed that the [BF4]− and [SbF6]− anions occupy the π-acidic cavities, establishing close directional F···Ctetrazine contacts with the tetrazine rings that are by ∼0.4 A shorter than the sum of the F···C van der Waals radii (∑RvdW F···C = 3.17 A). The number and strength of F···Ctetrazine contacts are maximized; the F···Ctetrazine distan...

Supramolecular architectures with π-acidic 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine cavities: role of anion-π interactions in the remarkable stability of Fe(II) metallacycles in solution.

Metallosupramolecular grid complexes (hereafter referred to as metallogrids) are well-defined oligonuclear metal ion complexes involving essentially planar arrays of the metal ions sited at the points of intersection of square or rectangular metallogrids and possess a variety of interesting optical, electronic, magnetic and supramolecular properties. Herein I aim to give the reader an overview of the synthesis, properties and potential for a variety of high-tech applications of metallogrids.

/pdf/metallosupramolecular-grid-complexes-towards-nanostructured-44bi7eceo2.pdf

Metallosupramolecular grid complexes: towards nanostructured materials with high-tech applications

The ligands 4,6-bis(pyrazol-1-yl)pyrimidine (bpzpm), 4,6-bis(3,5-dimethylpyrazol-1-yl)pyrimidine (bpz(*)pm), 4,6-bis(4-methylpyrazol-1-yl)pyrimidine (Mebpzpm), and 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine (ppdMe) were synthesized and were made to react with Cu(I) centers in the presence of different counteranions. Different [2 x 2] metallic grids were obtained. With ligands bpzpm, bpz*pm, and Mebpzpm, a new type of grid was obtained where the facing ligands were divergent and two counteranions (BF(4-) or PF(6-)) were hosted in the resulting cavities and exhibit C-H...F and anion...pi interactions in the solid state. The presence of methyl groups on the pyrazolyl rings induced several distortions in the structure. In complexes with the ligand ppdMe, there were found two groups of parallel ligands in the grid, and the cavities generated were smaller. The counteranions were situated outside the grid, and the facing ligands exhibited aromatic pi-pi stacking interactions. Anion-pi interactions involving the pyridazine ring were found. The behavior in solution of the new derivatives with a special emphasis on the cation-anion interactions was studied by UV-vis and NMR spectroscopy. Diffusion NMR experiments performed for some complexes allowed us to conclude that weak cation-anion interactions exist in solution, with the counteranions undergoing fast exchange on the diffusion time scale between the free and ion-paired states.

Self-assembly of ligands designed for the building of a new type of [2 x 2] metallic grid. anion encapsulation and diffusion NMR spectroscopy.

New coordination polymers have been obtained by the self-assembly of silver salts AgX (X = BF4, PF6, CF3SO3) and 2,4-diamino-6-R-1,3,5-triazines L (R = phenyl and p-tolyl) of formulas AgLX (1−6). A complex of different stoichiometry, [Ag3L2(H2O)(acetone)2](BF4)3, 7 (R = phenyl), has also been synthesized. The three-dimensional structures of five compounds have been determined by X-ray diffraction studies. For the AgLX complexes, when X = BF4 and R = phenyl or p-tolyl, chiral chains with alternating Ag and L are formed. The chains are cross-linked by the counteranions in a three-dimensional fashion through hydrogen bonds and weak Ag···F interactions giving rise to a structure with solvent-filled channels. Different and more compact structures have been found when the counteranion is CF3SO3 (OTf). When R = phenyl, sheets are formed which consist of [Ag2(OTf)2L2] units with double triflate bridges and which contain columns of π−π stacked arenes. Hydrogen bonds connect the sheets. When AgOTf is used and R is ...

Anion-dependent self-assembly of silver(I) and diaminotriazines to coordination polymers: non-covalent bonds and role interchange between silver and hydrogen bonds.

Kurt Mereiter

Papers

Self-assembly of ligands designed for the building of a new type of [2 x 2] metallic grid. anion encapsulation and diffusion NMR spectroscopy.

Anion-dependent self-assembly of silver(I) and diaminotriazines to coordination polymers: non-covalent bonds and role interchange between silver and hydrogen bonds.

Novel BPPFA Palladium Complexes. P,P to P,N Rearrangements Promoted by Chelating κ3-N,P,P-BPPFA Intermediates

Formation of Fischer-Type Aminocarbenes by a Double C-H Bond Activation of a Methylamino Group