Rare-Earth Metal-Enabled Ring-Opening Metathesis of Benzene.

Activation and transformation of inert C-C bonds within arenes are challenging and important topics in synthetic chemistry. While there have been some reports on the activation of C-C bonds in arene rings, the realm of metathesis reactions involving arene C-C bonds remains unexplored. Here, we report a rare-earth metal-enabled intramolecular metathesis reaction of one benzene C-C bond and another C-C single bond, assisted by the high reactivity and unique synergistic effect of rare-earth metallacycles.

A (CMe)/enolamido lutetium dinitrogen complex promoted by deprotonation on the amidinate ligand.

Selective deprotonation of the amidinate ligand in lutetium dinitrogen complex [{Cp*{MeC(NPr)}Lu}(μ-η:η-N)][K(crypt)] (Cp* = (CMe), crypt = 2,2,2-cryptand) afforded the novel Cp*/enolamido lutetium dinitrogen complex [{Cp*{HCC(NPr)}Lu}(μ-η:η-N)K][K(crypt)]. Due to the skeleton tension, a further rearrangement was confirmed with the formation of [{Cp*K{HCC(NPr)}Cp*Lu}(μ-η:η-N)][K(crypt)].

Cascade C-H Activation and Two C-C Bond Forming in Reaction of Azalutetacyclopentadiene with 2-Methylbenzonitriles.

Azametallacyclopentadienes are an important class of metallacycles as the key intermediates in metal-promoted or catalyzed carbon-carbon coupling reaction of nitriles and alkynes. Rare-earth azametallacyclopentadienes have shown various reactivity toward nitriles, depending on the substituents of nitriles. The reaction of azalutetacyclopentadienes toward 2-methylbenzonitriles has been investigated in this work, which selectively affords the fused 7-5-6-membered azalutetacycles as products.

Monomethylation and -protonation of Lutetium Dinitrogen Complex.

Due to the highly chemically inert nature, direct activation and transformation of dinitrogen are challenging. Here, we disclose the synthesis, isolation, and derivatization of (N) supported by lutetium complex. Initially, a (N) radical, in [{(CMe){MeC(NPr)}Lu}(μ-η:η-N)][K(crypt)] (crypt = 2,2,2-cryptand) complex, was generated through the reduction of neutral lutetium dinitrogen complex [{(CMe){MeC(NPr)}Lu}(μ-η:η-N)] with potassium metal.

Nonplanar Aromaticity of Dinuclear Rare-Earth Metallacycles.

While the concept of metalla-aromaticity has well been extended to transition organometallic compounds in diverse geometries, aromatic rare-earth organometallic complexes are rare due to the special (n - 1)d configuration and high-lying (n - 1)d orbitals of rare-earth centers. In particular, nonplanar cases of rare-earth complexes have not been reported so far. Here, we disclose the nonplanar aromaticity of dinuclear scandium and samarium metallacycles characterized by various aromaticity indices (nucleus-independent chemical shift, isochemical shielding surface, anisotropy of induced current density, and isomerization stabilization energy).

-Aryloxide-Amidinate Thorium Complexes.

An -aryloxide-amidine ligand (), [ONNO] ligand, integrating phenoxide (PhO) and amidine ligands through methylene linkers, was employed in actinide chemistry. Upon reaction of the deprotonated ligand with ThCl(DME) in ether, the corresponding dimer complex was obtained. Upon treatment of with KCp* (Cp* = Cp(Me)) in tetrahydrofuran, the corresponding {[ONNO]ThCp*(LiCl)} () was obtained.

Unusual Electronic Structures of an Electron Transfer Series of [Cr(μ-η : η -N )Cr].

In dinitrogen (N ) fixation chemistry, bimetallic end-on bridging N complexes M(μ-η  : η -N )M can split N into terminal nitrides and hence attract great attention. To date, only 4d and 5d transition complexes, but none of 3d counterparts, could realize such a transformation. Likewise, complexes {[Cp*Cr(dmpe)] (μ-N )} (1-3) are incapable to cleave N , in contrast to their Mo congeners.

Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes.

ConspectusThe activation and functionalization of N to form nitrogen-element bonds have long posed challenges to industrial, biological, and synthetic chemists. The first transition-metal dinitrogen complex prepared by Allen and Senoff in 1965 provoked researchers to explore homogeneous N fixation. Despite intensive research in the last six decades, efficient and quantitative conversion of N to diazenido and hydrazido species remains problematic.

Direct Synthesis of Phosphoryltriacetates from White Phosphorus via Visible Light Catalysis.

Organophosphorus compounds (OPCs) are widely used in many fields. However, traditional synthetic routes in the industry usually involve multistep and hazardous procedures. Therefore, it's of great significance to construct such compounds in an environmentally-friendly and facile way.

-aryloxide-amidinate group 4 metal complexes.

A -aryloxide-amidine ligand (HL), integrating phenoxide (PhO) and amidine ligands through methylene linkers, has been synthesized from 2-(aminomethyl)-6-(-butyl)phenol in two steps. Upon reacting the deprotonated HL ligand with group 4 metal chloride MCl, a corresponding (LM-Cl) dimer could be obtained. The coordination modes exhibit variation depending on the radius of the metal ions.

Insight into the Ligand-to-Ligand Charge-Transfer Process in Rare-Earth-Metal Diradical Complexes.

While a ligand-to-ligand charge-transfer (LLCT) process is an important way to understand the interactions between metal-bridged radicals for late-transition-metal complexes, there is little clear and evident observation of the LLCT process for rare-earth-metal complexes. In this work, rare-earth-metal diradical complexes supported by diazabutadiene (DAD) ligands [(DAD)RE(BH)] [RE = Yb (), Sm ()] were synthesized and studied. The coordination geometries of and are different due to the different ionic radii.

Snapshots of Early-Stage Quantitative N Electrophilic Functionalization.

Electrophilic functionalization of N moieties in metal dinitrogen complexes typically initiates the catalytic synthesis of N-containing molecules directly from N. Despite intensive research in the last six decades, how to efficiently and even quantitatively convert N into diazenido and hydrazido species still poses a great challenge. In this regard, systematic and comprehensive investigations to elucidate the reaction intricacies are of profound significance.

Selective Cleavage of the Strong or Weak C-C Bonds in Biphenylene Enabled by Rare-Earth Metals.

Selective cleavage of C-C bonds within arene rings is of great interest but remains elusive, especially for the molecules possessing the active and inert C-C bonds. Here, we report that the active and inert C-C bonds of biphenylene could be controllably cleaved by the reaction of biphenylene, potassium graphite, and rare-earth complexes with different metal centers. For scandium, the bond activation occurs at the C-C single bond, yielding 9-scandafluorene.

From Dinitrogen to N-Containing Organic Compounds: Using Li CN as a Synthon.

Through the synergies of a heterogeneous synthetic approach and a homogeneous synthetic methodology, N-containing organic compounds can be synthesized via activated N-containing species prepared from N gas and suitable carbon sources. From N , carbon, and LiH, we have previously succeeded in the high-yield preparation of Li CN as the activated N-containing species. In this work, we applied Li CN as a novel synthetic synthon for constructing N-containing organic compounds.

Dinitrogen Functionalization Affording Chromium Diazenido and Side-on η-Hydrazido Complexes.

Isolation of key intermediate complexes in dinitrogen functionalization is crucial for elucidating the mechanistic details and further investigation. Herein, the synthesis and characterization of (μ-η:η-N)(η-N)-Cr(I) and (η-N)-Cr(0) complexes supported by Cp* (Cp* = CMe) and NHC ligands were reported. Further functionalization of Cr(0)-N complex with silyl halides delivered the key intermediates in the alternating pathway, the chromium diazenido complex and the chromium side-on η-hydrazido complex .

Synthesis of pyrimidines from dinitrogen and carbon.

The element nitrogen and nitrogenous compounds are vital to life. The synthesis of nitrogen-containing compounds using dinitrogen as the nitrogen source, not through ammonia, is of great interest and great value but remains a grand challenge. Herein, we describe a strategy to realize this transformation by combining the heterogeneous approach with the homogeneous methodology.

Dinitrogen activation by a phosphido-bridged binuclear cobalt complex.

By reacting the semi-rigid PNP ligand with CoBr, the corresponding complex PNPCoBr (1) was obtained. The reduction of 1 with excess amounts of KC in THF under a N atmosphere yielded a binuclear cobalt dinitrogen anion complex [Co(μ-CyP)PCyN]K (2) the C-P bond cleavage of the PNP ligand. By adding 2,2,2-cryptand into complex 2, an ion pair Co complex, [Co(μ-CyP)PCyN]K(crypt-222) (3), could be effectively prepared.

Cobalt Cyclopentadienyl-Phosphine Dinitrogen Complexes.

By applying the potassium salts of cyclopentadienyl-phosphine ligands LK to CoCl , the corresponding cobalt chlorides (1, LCo Cl) were prepared. By reducing complexes 1 with KHBEt under a N atmosphere, bridging end-on complexes, LCo -N -Co L (2 a and 2 b), were successfully obtained. N -labeled [ N ]-2 a was prepared under N / N exchange in THF solution.

Synthesis and isolation of dinuclear N,C-chelate organoboron compounds bridged by neutral, anionic, and dianionic 4,4'-bipyridine reductive coupling of pyridines.

The reaction of Bppy(Mes)2 (BN1; ppy = 2-phenylpyridine) and BCHppy(Mes) (BN3) with the reducing reagent KC resulted in C-C bond formation intermolecular radical coupling to generate the 4,4'-bipyridyl ligand compounds BN2 and BN4. Adding 1 equivalent of KC to a THF solution of BN2 and BN4 generated the 4,4'-bipyridyl radical anions BN2K and BN4K. The dianion species BN2K2 and BN4K2 could be obtained by adding 2 equivalents of KC to the THF solution of BN2 and BN4.

Switchable assembly and function of antibody complexes in vivo using a small molecule.

The antigen specificity and long serum half-life of monoclonal antibodies have made them a critical part of modern therapeutics. These properties have been coopted in a number of synthetic formats, such as antibody-drug conjugates, bispecific antibodies, or Fc-fusion proteins to generate novel biologic drug modalities. Historically, these new therapies have been generated by covalently linking multiple molecular moieties through chemical or genetic methods.

Trisyl-based multidentate ligands: synthesis and their transition-metal complexes.

Herein we report the synthesis and applications of unusual trisyl-based multidentate ligands [trisyl = tris(trimethylsilyl)methyl, -C(SiMe)]. First, by applying a new trisyl synthon (MeSi)CH(SiMeCHCl) 1, trisyl-based S- or N-containing compounds 2 were efficiently obtained. On treatment of these compounds 2 with MeLi, their corresponding S- or N-coordinated pincer-like trisyl-based lithium salts 3, including the S-bridged ditrisyl compound 3a [Li{C(SiMe)SiMeCHSCHSiMeC(SiMe)}Li(DME)] and the N-coordinated monotrisyl compounds 3b [(NacNacLiCHSiMeC(SiMe)Li(THF)], 3c [Li(THF){C(SiMe)SiMeCHN(Me)CHCHN-2}], and 3d [Li{C(SiMe)SiMeCHN(Me)CHCHN(Pr)}] were synthesized and structurally characterized by single-crystal X-ray structural analysis.

Preparation of Radiolabeled Antibodies for Nuclear Medicine Applications in Immuno-Oncology.

The mixed patient responses to antibodies targeting immune checkpoint proteins (e.g., CTLA-4, PD-1, PD-L1) have generated tremendous interest in discovering biomarkers that predict which patients will best respond to these treatments.