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)].

Dinitrogen reduction chemistry with scandium provides a complex with two side-on (N[double bond, length as m-dash]N) ligands bound to one metal: (CMe)Sc[(µ-η:η-N)Sc(CMe)].

Although there are few reduced dinitrogen complexes of scandium, this metal has revealed a new structural type in reductive dinitrogen chemistry by reduction of bis(pentamethylcyclopentadienyl) scandium halides under N. Reduction of (Cp* = CMe) with potassium graphite (KC) under dinitrogen generates the dark blue paramagnetic complex , 1. This end-on bridging (N[double bond, length as m-dash]N) complex is a diradical with a magnetic moment of 2.

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.

-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.

-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.

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.

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.

Direct conversion of N and O: status, challenge and perspective.

As key components of air, nitrogen (N) and oxygen (O) are the vital constituents of lives. Synthesis of NO, and C-N-O organics direct from N and O, rather than from an intermediate NH (known as the Haber-Bosch process), is tantalizing. However, the extremely strong N≡N triple bond (945 kJ mol) and the nonpolar stable electron configuration of dinitrogen lead to its conversion being extensively energy demanding.

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.

(-Bu)NBr-Promoted N Splitting to Molybdenum Nitride.

Splitting of N via six-electron reduction and further functionalization to value-added products is one of the most important and challenging chemical transformations in N fixation. However, most N splitting approaches rely on strong chemical or electrochemical reduction to generate highly reactive metal species to bind and activate N, which is often incompatible with functionalizing agents. Catalytic and sustainable N splitting to produce metal nitrides under mild conditions may create efficient and straightforward methods for N-containing organic compounds.

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.

C,C- and C,N-Chelated Organocopper Compounds.

Copper-catalyzed and organocopper-involved reactions are of great significance in organic synthesis. To have a deep understanding of the reaction mechanisms, the structural characterizations of organocopper intermediates become indispensable. Meanwhile, the structure-function relationship of organocopper compounds could advance the rational design and development of new Cu-based reactions and organocopper reagents.

Metalla-aromatics: Planar, Nonplanar, and Spiro.

ConspectusThe concept of aromaticity is one of the most fundamental principles in chemistry. It is generally accepted that planarity is a prerequisite for aromaticity, and typically the more planar the geometry of an aromatic compound is, the stronger aromatic it is. However, it is not always the case, particularly when transition metals are involved in conjugation and electron delocalization of aromatic systems, i.

A tris-spiro metalla-aromatic system featuring Craig-Möbius aromaticity.

As aromaticity is one of the most fundamental concepts in chemistry, the construction of aromatic systems has long been an important subject. Herein, we report the synthesis and characterization of a tris-spiroaromatic complex, hexalithio spiro vanadacycle 2. The delocalization of the four electrons within the two V 3d orbitals and the π* orbitals of the three biphenyl ligands leads to a 40π Craig-Möbius aromatic system with three metalla-aromatic rings, as revealed by both experimental measurements and theoretical analyses.

Synthesis, Structure, and Magnetic Properties of Rare-Earth Bis(diazabutadiene) Diradical Complexes.

New kinds of diradical rare-earth metal complexes supported by diazabutadiene (DAD) ligands, [(DAD)LnN(TMS)] (; Ln = Dy, Lu; TMS = SiMe), were synthesized and studied. They showed a new [radical-Ln-radical] alignment with distorted square-pyramidal geometry. Structural and density functional theory analysis illustrated the radical anionic nature of the ligands.

Cyclic Bis-alkylidene Complexes of Titanium and Zirconium: Synthesis, Characterization, and Reaction.

Transition-metal alkylidenes have exhibited wide applications in organometallic chemistry and synthetic organic chemistry, however, cyclic Schrock-carbene-like bis-alkylidenes of group 4 metals with a four-electron donor from an alkylidene have not been reported. Herein, the synthesis and characterization of five-membered cyclic bis-alkylidenes of titanium (4 a,b) and zirconium (5 a,b) are reported, as the first well-defined group 4 metallacyclopentatrienes, by two-electron reduction of their corresponding titana- and zirconacyclopentadienes. DFT analyses of 4 a show a four-electron donor (σ-donation and π-donation) from an alkylidene carbon to the metal center.

Butadienyl Diiron Complexes: Nonplanar Metalla-Aromatics Involving σ-Type Orbital Overlap.

A new class of nonplanar metalla-aromatics, diiron complexes bridged by a 1,3-butadienyl dianionic ligand, were synthesized in high yields from dilithio reagents and two equivalents of FeBr . The complexes consist of two antiferromagnetically coupled high-spin Fe centers, as revealed by magnetometry, Mössbauer spectroscopy, and DFT calculations. Furthermore, experimental (X-ray structural analysis) and theoretical analyses (NICS, ICSS, AICD, MOs) suggest that the complexes are aromatic.

Carbodiimide-based synthesis of N-heterocycles: moving from two classical reactive sites to chemical bond breaking/forming reaction.

Carbodiimides are a unique class of heterocumulene compounds that display distinctive chemical properties. The rich chemistry of carbodiimides has drawn increasing attention from chemists in recent years and has made them exceedingly useful compounds in modern organic chemistry, especially in the synthesis of N-heterocycles. This review has outlined the extensive application of carbodiimides in the synthesis of N-heterocycles from the 1980s to today.