Transition-Metal-like Behavior of Main Group Elements: Ligand Exchange at a Phosphinidene

(Phosphino)­phosphaketenes (>PPCO) behave as (phosphino)­phosphinidene-carbonyl adducts (>PP←:CO). CO scrambling was observed using ¹³C labeled CO, and exchange reactions with phosphines afford the corresponding (phosphino)­phosphinidene–phosphine adducts (>PP←:PR₃). The latter react with isonitriles and singlet carbenes giving (phosphino)­phosphinidene–isonitrile (>PP←:CNR) and −carbene adducts (>PP←:C<). Based on experimental results and DFT calculations, it is shown that these “ligand” exchange reactions occur via an associative mechanism as classically observed with transition metal complexes

Gold-Catalyzed Intermolecular Markovnikov Hydroamination of Allenes with Secondary Amines

A cationic (CAAC)gold(I) complex promotes the addition of all types of nontertiary amines to a variety of allenes, affording allylic amines in good to excellent yields; the amino fragment always adds to the less substituted terminus of the CCC skeleton

Stable Planar Six-π-Electron Six-Membered N-Heterocyclic Carbenes with Tunable Electronic Properties

Carbene analogues of borazines are highly thermally stable. Keeping quasi-identical steric demands, the electronic properties of the carbene can be precisely tuned by varying the nature of the substituents at the boron centers

Reluctance of 4-Chloro-5-metalla-1,3,2-diazaborolines To Undergo Metal Halide β-Elimination: An Opportunity for C-Functionalization of 1,3,2-Diazaborolines

N,N′-Bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene reacts with dichlorophenylborane, affording the N,N′-bis(2,6-diisopropylphenyl)-2-phenyl-4-chloro-1,3,2-diazaboroline in a one-step process. The addition of lithium diisopropylamide gives rise to the 4-chloro-5-lithio-1,3,2-diazaboroline derivative, which cleanly undergoes a transmetalation reaction with TiCl4·2THF. Both the lithium and titanium complexes are stable with respect to metal chloride elimination and have been characterized by multinuclear NMR spectroscopy and by single-crystal X-ray diffraction studies. These findings open an avenue for the C-functionalization of 1,3,2-diazaborolines

Reluctance of 4-Chloro-5-metalla-1,3,2-diazaborolines To Undergo Metal Halide β-Elimination: An Opportunity for C-Functionalization of 1,3,2-Diazaborolines

N,N′-Bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene reacts with dichlorophenylborane, affording the N,N′-bis(2,6-diisopropylphenyl)-2-phenyl-4-chloro-1,3,2-diazaboroline in a one-step process. The addition of lithium diisopropylamide gives rise to the 4-chloro-5-lithio-1,3,2-diazaboroline derivative, which cleanly undergoes a transmetalation reaction with TiCl4·2THF. Both the lithium and titanium complexes are stable with respect to metal chloride elimination and have been characterized by multinuclear NMR spectroscopy and by single-crystal X-ray diffraction studies. These findings open an avenue for the C-functionalization of 1,3,2-diazaborolines

Stable Planar Six-π-Electron Six-Membered N-Heterocyclic Carbenes with Tunable Electronic Properties

Carbene analogues of borazines are highly thermally stable. Keeping quasi-identical steric demands, the electronic properties of the carbene can be precisely tuned by varying the nature of the substituents at the boron centers

Synthesis of 4- and 4,5-Functionalized Imidazol-2-ylidenes from a Single 4,5-Unsubstituted Imidazol-2-ylidene

Synthesis of 4- and 4,5-Functionalized Imidazol-2-ylidenes from a Single 4,5-Unsubstituted Imidazol-2-yliden

Synthesis of 4- and 4,5-Functionalized Imidazol-2-ylidenes from a Single 4,5-Unsubstituted Imidazol-2-ylidene

Synthesis of 4- and 4,5-Functionalized Imidazol-2-ylidenes from a Single 4,5-Unsubstituted Imidazol-2-yliden

Synthesis of 4- and 4,5-Functionalized Imidazol-2-ylidenes from a Single 4,5-Unsubstituted Imidazol-2-ylidene

Synthesis of 4- and 4,5-Functionalized Imidazol-2-ylidenes from a Single 4,5-Unsubstituted Imidazol-2-yliden

Singlet (Phosphino)phosphinidenes are Electrophilic

A room-temperature stable (phosphino)-phosphinidene reacts with carbon monoxide, stable singlet carbenes, including the poor π-accepting imidazol-2-ylidene, and phosphines giving rise to the corresponding phosphaketene, phosphinidene-carbene and phosphinidene-phosphine adducts, respectively. Whereas the electronic ground-state calculations indicate a PP multiple bond character in which the terminal phosphorus is negatively charged, the observed reactivity clearly indicates that (phosphino)­phosphinidenes are electrophilic as expected for an electron-deficient species. This is further demonstrated by competition experiments as well as by the results of Fukui function calculations