Borabenzene Adducts of Ylidic Lewis Bases. Syntheses and Structures of 3,5-Me₂C₅H₃BCH₂PPh₃, 3,5-Me₂C₅H₃BCH(SiMe₃)PPh₃, and C₅H₅BN(Ph)PPh₃¹

Abstract

The methylenephosphorane Ph3PCH2 reacts with 1-chloro-3,5-dimethyl-2-(trimethylsilyl)-1,2-dihydroborinine (2c) (in a 2/1 ratio) at ambient temperature to produce (triphenylphosphonio)methanide−3,5-dimethylborabenzene, 3,5-Me2C5H3BCH2PPh3 (3), with 1 equiv of (Ph3PCH2SiMe3)Cl (4), and (trimethylsilyl)(triphenylphosphonio)methanide−3,5-dimethylborabenzene, 3,5-Me2C5H3BCH(SiMe3)PPh3 (5), with 1 equiv of (PMePh3)Cl (6). Both adducts 3 and 5 are yellow crystalline compounds. Treatment of the iminophosphorane Ph3PNPh with an isomer mixture of 1-chloro(trimethylsilyl)dihydroborinines (8) produces N-(triphenylphosphonio)anilide−borabenzene C5H5BN(Ph)PPh3 (9) as brown-yellow crystals. The reaction of PMe3 with 2c affords the colorless trimethylphosphine adduct 3,5-Me2C5H3BPMe3 (10). The structures of the new adducts 3, 5, and 9 are reported. They do not show conjugation between the two remote charge centers, even in the case of the iminophosphorane adduct 9.

Synthesis, Structure, and Reactivity of a Dihydrido Borenium Cation

“…As a result, the C1ÀB1 distance in 3 (1.5030 (17) ) is shorter than the C À B single bonds reported for other borenium cations (1.62-1.58 ). [12] It should be noted however that it is longer than in typical C = B bonds (1.35-1.45 ) [13] while it compares quite well with the CÀB distances reported for borabenzenes (1.50-1.47 ), where the CÀB bond order is 1.5. [14] Thus, the p interaction, although essential for the stability of 3, might not be very strong.…”

“…Sum of angles around B1 360.08, torsion angle P1-C1-B1-H1a 1.68. [11] Figure 2. DFT optimized geometry of 3 with a plot of the HOMO.…”

Synthese, Struktur und Reaktivität eines Dihydridoboreniumkations

“…[9] Folglich ließen wir das Carbodiphosphoran 1 mit dem Boran-Dimethylsulfid-Komplex reagieren und isolierten das Addukt 2 als hellgelben Feststoff in quantitativer Ausbeute (Schema 2). [10] (17) ) kürzer als C-B-Einfachbindungen in anderen Boreniumkationen (1.62-1.58 ), [12] jedoch auch länger als eine typische C-B-Doppelbindung (1.35-1.45 ). [13] Sie ist ziemlich gut mit den C-B-Bindungen in Borabenzolen (1.50-1.47 ) mit einer C-B-Bindungsordnung von 1.5 [14] vergleichbar.…”

“…Winkelsumme um B1: 360.08; Torsionswinkel P1-C1-B1-H1a: 1.68. [11] Abbildung 2. DFT-optimierte Geometrie von 3 mit graphischer Darstellung des HOMO.…”

Insights into the Formation of Borabenzene Adducts via Ligand Exchange Reactions and TMSCl Elimination from Boracyclohexadiene Precursors

“…In such regard, it was observed that the phospholyl complex CpFe(3,4-Me2C4H2P) failed to react with the boracyclohexadiene precursor to generate a borabenzene adduct because of the lack of nucleophilicity at the phosphorous atom. 16 Scheme 1. General synthesis of neutral borabenzene adducts.…”