Construction of N-E bonds via Lewis acid-promoted functionalization of chromium-dinitrogen complexes.

Direct conversion of dinitrogen (N) into N-containing compounds beyond ammonia under ambient conditions remains a longstanding challenge. Herein, we present a Lewis acid-promoted strategy for diverse nitrogen-element bonds formation from N using chromium dinitrogen complex [Cp*(IPrMe)Cr(N)]K (1). With the help of Lewis acids AlMe and BF, we successfully trap a series of fleeting diazenido intermediates and synthesize value-added compounds containing N-B, N-Ge, and N-P bonds with 3 d metals, offering a method for isolating unstable intermediates.

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.

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 .

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.

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.

Synthesis and reactivity of asymmetric Cr(i) dinitrogen complexes supported by cyclopentadienyl-phosphine ligands.

Asymmetric trinuclear and dinuclear Cr(i) dinitrogen complexes bearing cyclopentadienyl-phosphine ligands were synthesized via reduction of their corresponding Cr(ii) chloride complexes in the presence of N. Oxidative addition reactions of single, double and triple bonds are found to take place on the low-valent Cr(i) centre.

Dinitrogen Functionalization Affording Chromium Hydrazido Complex.

A series of trinuclear and dinuclear Cr(I)-N complexes bearing cyclopentadienyl-phosphine ligands were synthesized and characterized. Further reduction of the Cr(I)-N complexes generated anionic Cr(0)-N complexes, which could react with MeSiCl to afford the first chromium hydrazido complex from N functionalization. These complexes were found to be effective catalysts for the transformation of N into N(SiMe).

Catalytic Lactonization of Unactivated Aryl C-H Bonds with CO: Experimental and Computational Investigation.

The first catalytic lactonization of unactivated aryl C-H bonds with CO to afford important phthalides is reported. Notably, this method features high selectivity, excellent functional group tolerance, smooth scalability, and facile product diversification. DFT calculations reveal that a novel insertion of two CO into the O-Pd bond of a palladacycle might be the key step, providing great potential and a different perspective for carbonylation with CO.

Oxy-Difluoroalkylation of Allylamines with CO via Visible-Light Photoredox Catalysis.

A selective oxy-difluoroalkylation of allylamines with carbon dioxide (CO) via visible-light photoredox catalysis is reported. These multicomponent reactions are efficient and environmentally friendly to generate a series of important 2-oxazolidinones with functionalized difluoroalkyl groups. The good functional group tolerance, broad substrate scope, easy scalability, mild reaction conditions, and facile functionalization of products provide great potential for application in organic synthesis and pharmaceutical chemistry.

Visible-Light-Driven Iron-Promoted Thiocarboxylation of Styrenes and Acrylates with CO.

The first thiocarboxylation of styrenes and acrylates with CO was realized by using visible light as a driving force and catalytic iron salts as promoters. A variety of important β-thioacids were obtained in high yields. This multicomponent reaction proceeds in an atom- and redox-economical manner with broad substrate scope under mild reaction conditions.

Selective Oxytrifluoromethylation of Allylamines with CO2.

Reported is the first oxy-trifluoromethylation of allylamines with carbon dioxide (CO2 ) using copper catalysis, thus leading to important CF3 -containing 2-oxazolidones. It is also the first time CO2 , a nontoxic and easily available greenhouse gas, has been used to tune the difunctionalization of alkenes from amino- to oxy-trifluoromethylation. Of particular note, this multicomponent reaction is highly chemo-, regio-, and diastereoselective under redox-neutral and mild reaction conditions.