Evaluation of Multisite Polypyridyl Ligands as Platforms for the Synthesis of Rh/Zn, Rh/Pd, and Rh/Pt Heterometallic Complexes

Enantioselective remote C-H activation directed by a chiral cation

Chiral cations have been used extensively as organocatalysts, but their application to rendering transition metal-catalyzed processes enantioselective remains rare. This is despite the success of the analogous charge-inverted strategy in which cationic metal complexes are paired with chiral anions. We report here a strategy to render a common bipyridine ligand anionic and pair its iridium complexes with a chiral cation derived from quinine. We have applied these ion-paired complexes to long-range asymmetric induction in the desymmetrization of the geminal diaryl motif, located on a carbon or phosphorus center, by enantioselective C-H borylation. In principle, numerous common classes of ligand could likewise be amenable to this approach.

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

Koneramines (L^R 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 , R=Ph or Ts) became major emergents whereas hemi-aminals (L^R 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. The reported results shed light on how to control the emergents of the multicomponent reaction mixture that forms koneramines. Reactivity studies of the intermediates pave the way for a new type of koneramine complexes that are new dipicolylamines where the two pyridine moieties of the resulting koneramine are not the same.

C-H Functionalisation for Hydrogen Isotope Exchange

The various applications of hydrogen isotopes (deuterium, D, and tritium, T) in the physical and life sciences demand a range of methods for their installation in an array of molecular architectures. In this Review, we describe recent advances in synthetic C-H functionalisation for hydrogen isotope exchange.

Supramolecular self-assembly of heterobimetallic complexes: a new N,P-based, selective heteroditopic ligand

Pyrimidine-hydrazone and phosphole architectures have been combined to create a new heteroditopic ligand capable of forming heterobimetallic Zn^II/Pd^II, Pb^II/Pd^II and Cu^II/Pd^II complexes in high yielding stepwise or one pot reactions. The catalytic activity of these complexes in Heck coupling and Miyaura borylation reactions was investigated.

Sophisticated Design of Covalent Organic Frameworks with Controllable Bimetallic Docking for a Cascade Reaction

Precise control of the number and position of the catalytic metal ions in heterogeneous catalysts remains a big challenge. Here we synthesized a series of two-dimensional (2D) covalent organic frameworks (COFs) containing two different types of nitrogen ligands, namely imine and bipyridine, with controllable contents. For the first time, the selective coordination of the two nitrogen ligands of the 2D COFs to two different metal complexes, chloro(1,5-cyclooctadiene)rhodium(I) (Rh(COD)Cl) and palladium(II) acetate (Pd(OAc)2 ), has been realized using a programmed synthetic procedure. The bimetallically docked COFs showed excellent catalytic activity in a one-pot addition-oxidation cascade reaction. The high surface area, controllable metal-loading content, and predesigned active sites make them ideal candidates for their use as heterogeneous catalysts in a wide range of chemical reactions.

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. Both syn-[Zn(L(Ph) OMe)Cl2 ] and anti-[Zn(L(Ph) OMe)Cl2 ] were characterized using NMR spectroscopy and mass spectrometry. Solid-state structures revealed that syn-[Zn(L(Ph) OMe)Cl2 ] adopted a square pyramidal geometry while anti-[Zn(L(Ph) OMe)Cl2 ] possesses a trigonal bipyramidal geometry around the Zn centers. The scope of this method was shown to be wide by varying the components of the dynamic coordination assembly, and the structures of the complexes isolated were confirmed by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Syn complexes were isolated as major products with Zn(II) and Cu(II) , and anti complexes were found to be major products with Ni(II) and Cd(II) . Hemiaminals and hemiaminal ethers are known to be unstable and are seldom observed as part of cyclic organic compounds or as coordinated ligands assembled around metals. It is now shown, with the support of experimental results, that linear hemiaminal ethers or thioethers can be assembled without the assistance of Lewis acidic metals in the multi-component assembly, and a possible pathway of the formation of hemiaminal ethers has been proposed.

Heterodinuclear complexes of 4,5-diazafluorene derivatives displaying η(5),κ(2)-[N,N] and η(5),κ(1)-N coordination modes

The syntheses and structures for a series of heterodinuclear complexes of 4,5-diazafluorenyl (L(-)) and 3,6-dimesityl-4,5-diazafluorenyl (LMes(-)) ligands are reported herein. In all these heterodinuclear complexes, the Ru(II) centre is sandwiched between a pentamethylcyclopentadienyl (Cp*) ligand and the C5 ring of L(-) or LMes(-) in a double η(5) fashion, while the other metal (Fe(II), Co(II), Pt(II), or Cu(I)) is bound to the N-donors.

The one pot synthesis of heterobimetallic complexes from a homoditopic pyrimidine–hydrazone ligand

Three new heterobimetallic complexes have been synthesised facilely in high yield and purity from a symmetric homoditopic pyrimidine-hydrazone ligand in a one-pot, two step reaction.

Selective one-pot syntheses of Pt(II)-Cu(I) heterobimetallic complexes of 4,5-diazafluorenide derivatives

We report both the stepwise and one-pot syntheses of Pt(II)-Cu(I) hetero-dinuclear complexes using 4,5-diazafluorenide (L(-)) and 9-(2-(diphenylphosphino)ethyl)-4,5-diazafluorenide (L(p)(-)) as binucleating ligands. In the case of L(p)(-), the tethered phosphine arm helps anchor the Pt(II) centre onto the carbon site of the diazafluorenide and the Cu(I) centre is bound to the N,N-chelate site. In the case of L(-), the Cu(I) centre is bound to the carbon site of diazafluorenide and the Pt(II) centre is coordinated to the N,N-chelate site.

Dichlorido[6,8,22,24,34,36-hexamethyl-33,35-diaza-3,11,19,27-tetraazoniapentacyclo[27.3.1.15,9.113,17.121,25]hexatriaconta-1(33),5,7,9(34),13,15,17(35),21,23,25(36),29,31-dodecaene-κ6N3,N11,N19,N27,N33,N35]dipalladium(II) bis(perchlorate)N,N-dimethylformamide disolvate methanol disolvate

In the crystal structure of the title compound, [Pd₂(C₃₆H₄₂N₆)Cl₂](ClO₄)₂·2C₃H₇NO·2CH₃OH, the dinuclear Pd^II complex cation lies on an inversion center. Each Pd^II ion has a distorted square-planar coordination sphere, defined by three N atoms of the macrocyclic ligand and a chloride ion. The Pd^II complex cations and the methanol mol­ecules are linked through N—H⋯O and O—H⋯O hydrogen bonds, forming a zigzag chain along [101]. An intra­molecular N—H⋯Cl hydrogen bond is also observed.