Reactions of Dianionic α-Diimine-Supported Dimagnesium(I) Compound [K(THF)3]2[LMg–MgL] with Nitriles

Mixing and matching N,N- and N,O-chelates in anionic Mg(I) compounds: synthesis and reactivity with RNCNR and CO

Reduction of [Mg(NON)]2 ([NON]2- = [O(SiMe2NDipp)2]2-, Dipp = 2,6-iPr2C6H3) affords Mg(I) species containing NON- and NNO-ligands ([NNO]2- = [N(Dipp)SiMe2N(Dipp)SiMe2O]2-). The products of reactions with iPrNCNiPr and CO are consistent with the presence of reducing Mg(I) centres. Extraction with THF affords [K(THF)2]2[(NNO)Mg-Mg(NNO)] with a structurally characterised Mg-Mg bond that was examined using density functional theory.

One-Electron (2c/1e) Tin···Tin Bond Stabilized by ortho-Phenylenediamido Ligands

Odd-electron bonds, i.e., the two-center, three-electron (2c/3e), or one-electron (2c/1e) bonds, have attracted tremendous interest owing to their novel bonding nature and radical properties. Herein, complex [K(THF)6][LSn:···Sn:L] (1), featuring the first and unsupported 2c/1e Sn···Sn σ-bond with a long distance (3.2155(9) Å), was synthesized by reduction of stannylene [LSn:] (L = N,N-dpp-o-phenylene diamide) with KC8. The one-electron Sn-Sn bond in 1 was confirmed by the crystal structure, DFT calculations, EPR spectroscopy, and reactivity studies. This compound can be viewed as a stabilized radical by delocalizing to two metal centers and can readily mediate radical reactions such as C-C coupling of benzaldehyde.

Complexation-Triggered Fluctuation of π-Conjugation on an Antiaromatic Dicyanoanthracene Dianion

The formation of Lewis pairs is an important chemical concept. Recently, the complexation of Lewis acidic tris(pentafluorophenyl)borane with Lewis basic moieties and subsequent reduction has emerged as a fascinating strategy for designing novel reactions and structures. The impact of the complexation and subsequent reduction of antiaromatic systems bearing Lewis base moieties has been investigated. We found how Lewis adduct formation stabilizes an antiaromatic system consisting of 9,10-dicyanoanthracene and tris(pentafluorophenyl)borane by using synthesis, X-ray crystallography, spectroscopic analysis, and quantum chemical calculations.

Assembly of metallo-macrocycles through reductive C-C coupling of alkylnitriles by an Mg-Mg-bonded compound

Low-valent metal complexes have attracted much research interest owing to their novel reactivities toward small molecules. Herein the reactivity of the α-diimine-ligated, Mg-Mg-bonded compound [K(THF)₃]₂[LMg-MgL] (1, L = [(2,6-iPr₂C₆H₃)NC(Me)]₂^2-) with aliphatic nitriles has been studied. Complex 1 readily activates n-alkylnitriles (RCN; R = propyl, butyl, and pentyl) to afford the unique trinuclear magnesium metallo-macrocyclic complexes, [LMg(μ-{(NC-C(R)C(CH₂R)-NH})]₃[K₃(Solv)₆] (2-4: R = -(CH₂)_nCH₃, n = 2, 3, or 4; Solv = THF/DME), through a reductive deprotonation of the α-H of one nitrile molecule and C-C coupling between this α-carbon and the cyanide (CN) group of another nitrile, followed by a 1,3-H shift. The results demonstrate the possibility of assembling supramolecular architectures based on the α-diimine [LMg] fragment through small molecule activation.

Nitrile formation via dichlorocarbene insertion into the Si–N bond of Ln(iii) bis(trimethylsilyl)amide complexes

Reactions of bis(trimethylsilyl)amino lanthanides and chloroform unprecedently generate the Me3SiCN complexes where the nitrile ligand is formed via insertion of dichlorocarbene into the Si–N bond of the lanthanide precursor.

Main-group metal complexes of α-diimine ligands: structure, bonding and reactivity

α-Diimine ligands, in particular 1,4-diazabutadiene (dad) and bis(iminoacenaphthene) (bian) derivatives, have been widely used for coordination with various metals, including main-group, transition, and lanthanide and actinide metals. In addition to their tunable steric and electronic properties, the dad and bian ligands are redox-active and can readily accept one or two electrons, converting into the radical-anionic (L˙^-) or dianionic (enediamido, L^2-) form, respectively. This non-innocence brings about rich electronic structures and properties of the ligands and complexes thereof. For example, the dad ligands in their three redox levels can effectively stabilize a series of metal centers in different oxidation states, including low-valent metals. Moreover, these ligands can serve as electron reservoirs and can participate in reactions toward other molecules with or without metals. Therefore, such ligands are extremely useful in the areas of low-valent complexes and small molecule activation. Herein, we will discuss the use of dad (and bian) ligands in the stabilization of metal-metal-bonded compounds, in particular those of main-group metals, as well as small molecule activation by these (low-valent) metal coordination species where the non-innocence of the ligands plays a key role.

Organometallo-macrocycle assembled through dialumane-mediated C-H activation of pyridines

Dialumane 1 reacts with pyridines at elevated temperatures through regioselective reductive dehydrogenation of 4-H, affording a unique hexanuclear Al(iii) macrocycle [{LAl(pyridyl)}6], which represents the first dialumane-mediated C-H activation of Py and may suggest a new approach toward organometallo supra-molecules by one-pot small molecule activation and self-assembly.

Transformation of carbodiimides to guanidine derivatives facilitated by gallylenes

The reductive coupling of carbodiimides RN[double bond, length as m-dash]C[double bond, length as m-dash]NR (R = 2,6-iPr2C6H3, Cy, iPr) by using [(dpp-bian)GaNa(dme)2] (1); [(dpp-dad)GaNa(thf)3] (2a) and [(dpp-dad)GaK(thf)4Ga(dpp-dad)][K(thf)6] (2b) led to the guanidinate derivatives [(dpp-bian)Ga(NCy)2C[double bond, length as m-dash]NCy][Na(thf)2] (3); [LGaN(R)C(RN)N(R)C(RN)][M] L = dpp-bian, M = Na(dme)2, R = iPr, (4a); L = dpp-dad, M = Na(thf)3, R = iPr, (4b); R = Cy, (4c); M = K(thf)4, (4d); L = dpp-bian, M = Na(dme)2, R = Cy, (4e) and [(dpp-dad)Ga(2,6-iPr2C6H3N)2C][Na(thf)2] (5).

Stabilization of Grignard reagents by a pillar[5]arene host – Schlenk equilibria and Grignard reactions

Grignard reagents with linear alkyl chains are encapsulated and stabilized by pillar[5]arene while preserving their reactivity in Grignard reactions.