A crystalline doubly oxidized carbene.

The chemistry of carbon is governed by the octet rule, which refers to its tendency to have eight electrons in its valence shell. However, a few exceptions do exist, for example, the trityl radical (PhC∙) (ref. ) and carbocation (PhC) (ref.

An Air-Stable "Masked" Bis(imino)carbene: A Carbon-Based Dual Ambiphile.

Carbenes, once considered laboratory curiosities, now serve as powerful tools in the chemical and material sciences. To date, all stable singlet carbenes are single-site ambiphiles. Here we describe the synthesis of a carbene which is a carbon-based ambiphile (both single-site dual-site).

A crystalline radical cation derived from Thiele's hydrocarbon with redox range beyond 1 V.

Thiele's hydrocarbon occupies a central role as an open-shell platform for new organic materials, however little is known about its redox behaviour. While recent synthetic approaches involving symmetrical carbene substitution of the CPh termini yield isolable neutral/dicationic analogues, the intervening radical cations are much more difficult to isolate, due to narrow compatible redox ranges (typically < 0.25 V).

Acid-Base Free Main Group Carbonyl Analogues.

Main group carbonyl analogues (R E=O) derived from p-block elements (E=groups 13 to 15) have long been considered as elusive species. Previously, employment of chemical tricks such as acid- and base-stabilization protocols granted access to these transient species in their masked forms. However, electronic and steric effects inevitably perturb their chemical reactivity and distinguish them from classical carbonyl compounds.

An Acid-Free Anionic Oxoborane Isoelectronic with Carbonyl: Facile Access and Transfer of a Terminal B═O Double Bond.

We disclose the synthesis and structural characterization of the first acid-free anionic oxoborane, [K(2.2.2-crypt)][(HCDippN)BO] (1) (Dipp = 2,6- PrCH), which is isoelectronic with classical carbonyl compounds.

An N-Heterocyclic Boryloxy Ligand Isoelectronic with N-Heterocyclic Imines: Access to an Acyclic Dioxysilylene and its Heavier Congeners.

Introduced here is a new type of strongly donating N-heterocyclic boryloxy (NHBO) ligand, [(HCDippN) BO] (Dipp=2,6-diisopropylphenyl), which is isoelectronic with the well-known N-heterocyclic iminato (NHI) donor class. This 1,3,2-diazaborole functionalized oxy ligand has been used to stabilize the first acyclic two-coordinate dioxysilylene and its Ge, Sn, and Pb congeners, thereby presenting the first complete series of heavier group 14 dioxycarbene analogues. All four compounds have been characterized by X-ray crystallography and density-functional theory, enabling analysis of periodic trends: the potential for the [(HCDippN) BO] ligand to subtly vary its electronic-donor capabilities is revealed by snapshots showing the gradual evolution of arene π coordination on going from Si to Pb.

Successive Protonation of an N-Heterocyclic Imine Derived Carbonyl: Superelectrophilic Dication Versus Masked Acylium Ion.

Carbonyl cations are among the most commonly invoked reactive intermediates in organic synthesis. While Olah pioneered superacids to provide a "stable ion" environment for their study in situ, isolated examples are rare. Here, we disclose successive protonation of an N-heterocyclic imine (NHI) derived carbonyl compound (IDippN) CO, 2, to the monocation [(IDippN)(IDippNH) CO] , [3] , and the doubly protonated dication [(IDippNH) CO] , [4] .

Nickel-Catalyzed Facile [2+2+2] Cyclotrimerization of Unactivated Internal Alkynes to Polysubstituted Benzenes.

A catalytic [2+2+2] cyclotrimerization of unactivated internal alkynes providing cyclotrimerization products in excellent yields with high regioselectivity is described. The transformation is accomplished by using a simple catalytic mixture comprising Ni(acac) , an imidazolium salt and a Grignard reagent at room temperature or 60 °C for 20 min or 1 h.

A dicationic iminophosphane.

A novel dicationic system containing a PN fragment has been synthesized and structurally characterized. According to the solid-state analysis and theoretical investigation, the dicationic iminophosphane resonance form is the most appropriate description for the dication. However, the contribution from the phosphorus mononitride resonance form is not negligible.

1,2,4,3-Triazaborole-based neutral oxoborane stabilized by a Lewis acid.

The first example of 1,2,4,3-triazaborole-based oxoborane has been synthesized via hydrogen migration upon the coordination of AlCl3 to the corresponding borinic acid. X-ray diffraction analysis and computational study disclosed the partial B[double bond, length as m-dash]O double-bond property.