The frustrated Lewis pairs (FLPs) derived from tBu 3 P and E(C 6 F 5 ) 3 (E = B, Al) react with pO 2 C 6 Cl 4 and Ph 3 SnH to give [tBu 3 POC 6 Cl 4 OE(C 6 F 5 ) 3 ] (E = B 1, Al 2), [tBu 3 PSnPh 3 ][HB(C 6 F 5 ) 3 ] 3, and [tBu 3 PSnPh 3 ][(m-H)(Al(C 6 F 5 ) 3 ) 2 ] 4. These products form via the accepted two-electron process involving a transient ''encounter complex.'' In contrast, the corresponding reactions of Mes 3 P and E(C 6 F 5 ) 3 (E = B, Al) with pO 2 C 6 Cl 4 give [(Mes 3 POC 6 Cl 4 OE(C 6 F 5 ) 3 ] (E = B 8, Al 9); however, the identification of the intermediates [Mes 3 P$] 2 [(C 6 F 5 ) 3 EOC 6 Cl 4 OE(C 6 F 5 ) 3 ] (E = B 5, Al 6) supports a mechanism that proceeds via a single-electron transfer process. This is further supported by the reactions of Mes 3 P and E(C 6 F 5 ) 3 (E = B, Al) with Ph 3 SnH, which yielded [Mes 3 PH] [HB(C 6 F 5 ) 3 ] 10 and [Mes 3 PH][(m-H)(Al(C 6 F 5 ) 3 ) 2 ] 11, respectively, with the concurrent formation of Ph 3 SnSnPh 3 .

Single electron transfer (SET) reactions are effected by the combination of a Lewis acid (e.g., E(CF) E = B or Al) with a small molecule substrate and decamethylferrocene (Cp*Fe). Initially, the corresponding reactions of (PhS) and (PhTe) were shown to give the species [Cp*Fe][PhSB(CF)] 1 and [Cp*Fe][(μ-PhS)(Al(CF))] 2 and [Cp*Fe][(μ-PhTe)(Al(CF))] 3, respectively. Analogous reactions with di-tert-butyl peroxide yielded [Cp*Fe][(μ-HO)(B(CF))] 4 with isobutene while with benzoyl peroxide afforded [Cp*Fe][PhC(O)OE(CF)] (E = B 5, Al 6). Evidence for a radical pathway was provided by the reaction of PhSnH and p-quinone afforded [Cp*Fe][HB(CF)] 7 and [Cp*Fe][(μ-OCH)(E(CF))] (E = B 8, Al 9). In addition, the reaction of TEMPO with Lewis acid and Cp*Fe afforded [Cp*Fe][(CHMeNOE(CF)] (E = B 10, Al 11). Finally, reactions with O, Se, Te and S gave [Cp*Fe][((CF)Al(μ-O)Al(CF))] 12, [Cp*Fe][((CF)Al(μ-Se)Al(CF))] 13, [Cp*Fe][(μ-Te)(Al(CF))] 14 and [Cp*Fe][(μ-S)B(CF))] 15, respectively. The mechanisms of these SET reactions are discussed, and the ramifications are considered.

Reaction of (Idipp)AlH3 with [Ph3C][B(C6F5)4] in toluene affords the dimeric aluminum dication [((Idipp)AlH(μ-H))2][B(C6F5)4]22. In contrast, the reaction of (IBn)AlH3 with [Ph3C][B(C6F5)4] in bromobenzene gives a redistribution product, the salt of a monomeric dication [(IBn)2AlH][B(C6F5)4]24.

The reactions of the cyclic alkyl amino carbene (CAAC) 1 with phosphaalkynes generate the kinetically unstable CAAC‐derived phosphirenes 4 and 5, which undergo rearrangement/dimerization reactions to give the vinyl‐substituted diphosphenes 2, 3, and 6. The P=P double bond scission of 2 or 3 is unprecedentedly effected by S8, [AuCl(tht)], or MeOTf at room temperature, which affords a dithiophosphorane 7, a phosphepine Au complex 8, or phosphepinium cations 9 and 10, respectively. The cationic species feature little homoaromaticity while representing the first examples of the phosphorus‐containing analogue of the tropylium ion.

NHC-stabilized parent sulfenyl (H-S), selenenyl (H-Se) and tellurenyl (H-Te) cations have been achieved by treatment of NHC chalcogen adducts with trifluoromethanesulfonic acid. Computational investigations show that most of the positive charges are localized at chalcogen atoms and carbene carbons with strong donor acceptor interactions between the lone pair of chalcogen atoms and the vacant orbital of the carbene centre, accounting for its unexpected stability.

Avenues to S-based Lewis acids were developed via the oxidation of aryl-sulfoxides with XeF, giving difluorodiarylsulfoxides which react via fluoride abstraction to afford Lewis acidic fluorosulfoxonium cations; this acidity is derived from the S-F σ* orbital and has been probed both experimentally and computationally.

A room-temperature-stable crystalline 2H-phosphirene (1) was prepared by treatment of an electrophilic diamidocarbene with tert-butylphosphaalkyne. Compound 1 is shown to react as a vinylphosphinidene generated via phosphirene-phosphinidene rearrangement. Thermolysis is shown to affect C-N bond scission while reactions with CClO or (tht)AuCl afford formal oxidation of the phosphindene center and the phosphinidene-insertion into an aromatic C-C bond of a mesityl group, respectively. The latter reaction is the first example of a phosphorus analog of the Büchner ring expansion reaction.

A room-temperature-stable crystalline cyclic (alkyl)(amino)nitrenium cation 2 features cationic nitrogen atom with a smaller HOMO-LUMO gap compared to that of a 1,2,3-triazolium 5 (an N-heterocyclic nitrenium cation). The low-lying LUMO of 2 results in an enhanced electrophilicity, which allowed for the formation of Lewis adducts with neutral Lewis bases, such as Me P, nBu P, and IiPr. The N-based Lewis acid 2 also forms an FLP with tBu P but subsequently reacts with (PrS) to cleave the S-S bond. Both experimental and theoretical results suggest that the Lewis acidity of 2 is stronger than its N analogues.