The magnet-like behavior can beobserved by slow relaxation of the magnetization below theblocking temperature. Since the discovery of SMMs in theearly 1990s, this assumption has formed the basis for theunderstanding of the origin of the anisotropic barrier.However, in recent years the development of novel lantha-nide-only SMMs that challenge and defy this theory pose anumber of questions:

A Polynuclear Lanthanide Single-Molecule Magnet with a Record

Among the recent developments in metal-organic frameworks (MOFs), porous layered coordination polymers (CPs) have garnered attention due to their modular nature and tunable structures. These factors enable a number of properties and applications, including gas and guest sorption, storage and separation of gases and small molecules, catalysis, luminescence, sensing, magnetism, and energy storage and conversion. Among MOFs, two-dimensional (2D) compounds are also known as 2D CPs or 2D MOFs. Since the discovery of graphene in 2004, 2D materials have also been widely studied. Several 2D MOFs are suitable for exfoliation as ultrathin nanosheets similar to graphene and other 2D materials, making these layered structures useful and unique for various technological applications. Furthermore, these layered structures have fascinating topological networks and entanglements. This review provides an overview of different aspects of 2D MOF layered architectures such as topology, interpenetration, structural transformations, properties, and applications.

Two-Dimensional Metal-Organic Framework Materials: Synthesis, Structures, Properties and Applications.

Recent advances in the catalytic hydroboration of carbonyl compounds

Transition metal catalyzed asymmetric hydrofunctionalization of readily available unsaturated hydrocarbons presents one of the most straightforward and atom-economic protocols to access valuable optically active products. For decades, noble transition metal catalysts have laid the cornerstone in this field, on account of their superior reactivity and selectivity. In recent years, from an economical and sustainable standpoint, first-row, earth-abundant transition metals have received considerable attention, due to their high natural reserves, affordable costs, and low toxicity. Meanwhile, the earth-abundant metal catalyzed hydrofunctionalization reactions have also gained much interest and been investigated gradually. However, since chiral ligand libraries for earth-abundant transition-metal catalysis are limited to date, the development of highly enantioselective versions remains a significant challenge.This Account summarizes our recent efforts in developing suitable chiral ligands for iron and cobalt catalysts and their applications in the highly enantioselective hydrofunctionalization reactions (hydroboration and hydrosilylation) of alkenes and alkynes. In ligand design, we envisioned that chiral unsymmetric NNN-tridentate (UNT) ligand scaffolds could promote these enantioselective transformations with earth-abundant metals. Therefore, several types of chiral UNT ligands were designed and prepared in our laboratory, utilizing readily available natural amino acids as chiral sources. In the very beginning, chiral oxazoline iminopyridine (OIP) ligands were proposed and investigated through the rational combination of nitrogen-containing ligand scaffolds. After a systematic survey of the ligand effects, the imine moiety in the rigid OIP ligands was replaced by a conformationally more flexible amine unit, leading to the construction of reactive oxazoline aminoisopropylpyridine (OAP) ligands. Subsequently, imidazoline iminopyridine (IIP) and thiazoline iminopyridine (TIP) ligands were prepared by altering the oxygen atom of oxazoline with nitrogen and sulfur linkers, respectively. To further expand the chiral ligand library, other tridentate ligands containing a twisted pincer, anionic, and nonrigid backbone were also designed and synthesized, including iminophenyl oxazolinyl phenylamine (IPOPA) and imidazoline phenyl picolinamide (ImPPA). The efficacy of these chiral UNT ligands for asymmetric induction in iron and cobalt catalysis has been demonstrated through asymmetric hydrofunctionalization of alkenes and asymmetric sequential hydrofunctionalization of alkynes, which exhibit excellent reactivity as well as high chemo-, regio-, and stereoselectivity with broad functional group tolerance. Notably, highly regio- and enantioselective hydrofunctionalization of challenging substrates, such as 1,1-disubstituted aryl alkenes and terminal aliphatic alkenes, was also achieved. Furthermore, the development of asymmetric sequential isomerization/hydroboration of internal alkenes and sequential hydrofunctionalization of alkynes further demonstrates the synthetic power of these catalytic systems. The chiral enantioenriched products obtained by these methodologies could be potentially utilized in organic synthesis, medicinal chemistry, and materials science. We believe that our continuous efforts in this field would be beneficial to the development of asymmetric earth-abundant metal catalysis.

Iron- and Cobalt-Catalyzed Asymmetric Hydrofunctionalization of Alkenes and Alkynes

Organoboron reagents represent a unique class of compounds because of their utility in modern synthetic organic chemistry, often affording unprecedented reactivity. The transformation of the carbon-boron bond into a carbon-X (X = C, N, and O) bond in a stereocontrolled fashion has become invaluable in medicinal chemistry, agrochemistry, and natural products chemistry as well as materials science. Over the past decade, first-row d-block transition metals have become increasingly widely used as catalysts for the formation of a carbon-boron bond, a transformation traditionally catalyzed by expensive precious metals. This recent focus on alternative transition metals has enabled growth in fundamental methods in organoboron chemistry. This review surveys the current state-of-the-art in the use of first-row d-block element-based catalysts for the formation of carbon-boron bonds.

First-Row d-Block Element-Catalyzed Carbon-Boron Bond Formation and Related Processes.

Catalytic hydroboration of alkenes is a well-established method to access borane-functionalized hydrocarbons. While linear-selective hydroboration was predominantly reported, catalysts enabling opposite selectivity (branched-selective) are attracting considerable interest, especially when Earth-abundant metals are utilized. This Synopsis summarizes recent progress in Earth-abundant-metal-catalyzed, branched-selective hydroboration of alkenes while overviewing the historical contributions to this reaction using precious metals. Lessons learned from the current state of this topic that can guide future catalyst design are presented, along with challenging issues that remain to be addressed.

Branched-Selective Alkene Hydroboration Catalyzed by Earth-Abundant Metals.

The reactions of copper(II) salts with simple terpyridine (tpy) ligands gave mononuclear monoligand complexes 1–3, of which two new structures have been characterized by X-ray crystallography. These complexes were applied as catalysts for the oxidation of benzylic alcohol to benzaldehyde in air in the presence of the radical 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO). Copper complexes 1 and 2 are efficient catalysts for the reactions in water at 70 °C with 4-dimethylaminopyridine (DMAP) as an extra base. The influence of TEMPO on the formation of new reactive intermediates during the catalytic reactions was tentatively investigated by introducing TEMPO into the reaction solutions of tpy derivatives with copper dichloride. Two new complexes with interesting solid-state structures resulting from these reactions have been isolated and characterized. The coordination reactions in the presence of TEMPO led to new mixed-valence CuICuII supramolecular assembles (4 and 5), although they adopt either discrete complex or 1D polymeric structures. Further catalytic studies indicated that the mixed-valence assembles 4 and 5 displayed higher catalytic activity than those of the mononuclear complexes under milder conditions. The relationship between the molecular structures of diverse copper complexes and their reactivity is discussed on the basis of the results obtained.

Copper(II) Complexes of 2,2′:6′,2″-Terpyridine Derivatives for Catalytic Aerobic Alcohol Oxidations – Observation of Mixed-Valence CuICuII Assembles

A novel copper/4-dimethylaminopyridine catalyst system has been found to catalyse the aerobic oxidation of a variety of primary and secondary alcohols in water at room temperature, in the presence of a TEMPO or ABNO nitroxyl radical. A tetranuclear CuII cluster was revealed to be a plausible reactive intermediate.

Mild, green copper/4-dimethylaminopyridine catalysed aerobic oxidation of alcohols mediated by nitroxyl radicals in water

One-dimensional copper(II) coordination polymers built on 4′-substituted 4,2′:6′,4″- and 3,2′:6′,3″-terpyridines: Syntheses, structures and catalytic properties

Catalytic hydroboration of ketones with pinacolborane was achieved with a 2D iron(ii) coordination polymer (CP) of a divergent 4,2';6',4''-terpyridine (tpy) derivative under mild conditions with high efficiency. This solid iron catalyst system is more active towards the hydroboration of ketones than that of aldehydes, displaying a different trend of reactivity from known homogeneous iron hydroboration catalysts.

Li Li

Papers

Branched-Selective Alkene Hydroboration Catalyzed by Earth-Abundant Metals.

Copper(II) Complexes of 2,2′:6′,2″-Terpyridine Derivatives for Catalytic Aerobic Alcohol Oxidations – Observation of Mixed-Valence CuICuII Assembles

Mild, green copper/4-dimethylaminopyridine catalysed aerobic oxidation of alcohols mediated by nitroxyl radicals in water

One-dimensional copper(II) coordination polymers built on 4′-substituted 4,2′:6′,4″- and 3,2′:6′,3″-terpyridines: Syntheses, structures and catalytic properties

Iron(II) coordination polymer catalysed hydroboration of ketones