Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition

Phosphine‐Stabilized Diiododiborenes: Isolable Diborenes with Six Labile Bonds

“…‐ However, the B=B bond is also labile, and a number of reactions involving its cleavage have been presented, some of which are followed (or preceded) by B−P bond cleavage. These include the insertion and complete C≡C bond cleavage of an alkyne, one‐electron oxidation with a tropylium cation and two‐electron oxidation with selenium, coordination to Cu I , Zn II , and Cd II[6f] (the former being followed by hydroarylation of the B=B bond), inverse‐electron‐demand Diels–Alder reactions with dienes, and 1,1‐ and 1,2‐diborations of the B=B bond…”

Uncatalyzed Hydrogenation of First‐Row Main Group Multiple Bonds

“…[15] Recent efforts in our group have focused on the uncatalyzed activation of small molecules by boron-boron multiple bonds, including the direct hydroboration of N-heterocyclic carbene (NHC) stabilized 1,2-diaryldiborenes, [16] the reductive insertion of elemental chalcogens by NHC-supported diborynes, [17] the activation of tert-butylisocyanide and CO by a cAAC-supported diboracumulene [18] , the reductive coupling of four CO molecules by NHC-supported diborynes [18] and, most recently, the cycloaddition of apolar alkynes to boron-boron multiple bonds. [20] In this contribution we now report the facile and selective hydrogenation of B-B multiple bonds to the corresponding 1,2-dihydrodiborenes, making these the first examples of spontaneous H2 activation by lighter alkene and alkyne analogues. First isolated by Robinson and co-workers, NHC-supported 1,2-dihydrodiborenes, (IDip)2B2H2 (1) and (IMes)2B2H2 (2) (IDip = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene), were obtained from the reduction of (IDip)BBr3 with KC8, alongside the corresponding tetrahydrodiboranes(6), (IDip)2B2H4 and (IMes)2B2H4, both resulting from hydrogen atom abstraction from the reaction solvent by radical intermediates (Scheme 1).…”

Bindungsstärkende Rückbindung in Aminoborylen‐stabilisierten Aminoborylenen: an der Grenze zwischen Borylenen und Diborenen

“…Die B-C CAAC -Bindungslängen für 4a, 4b und 4c liegen bei 1.495(2), 1.467(2) bzw.1 .490- (4) .D iese Werte spiegeln das grçßere Maß an B-C CAAC -Doppelbindungscharakter in 4b wider, da diese Verbindung die schwach p-akzeptierende PMe 3 -Gruppe trägt. 11 B-NMR-Signale für 4b und 4c wurden im typischen Borylenbereich bei d = 1 bzw.…”

“…[1] Beispiele fürd as "Metallmimetische" Verhalten von Bor(I)-Spezies sind die Aktivierung von CO, [2] H 2 [2a, 3] und Alkinen [4] sowie der kürzlich erfolgte Abfang von N 2 und dessen Reduktion und Verkettung. [1] Beispiele fürd as "Metallmimetische" Verhalten von Bor(I)-Spezies sind die Aktivierung von CO, [2] H 2 [2a, 3] und Alkinen [4] sowie der kürzlich erfolgte Abfang von N 2 und dessen Reduktion und Verkettung.…”