Synthesis and Reactivity of Alkynyl‐Linked Phosphonium Borates

Abstract

The phosphine tBu(2 PC[triple bond]CH (1) was reacted with B(C(6)F(5)) to give the zwitterionic species tBu(2)P(H)C[triple bond]CB(C(6)F(5))(3) (2). The analogous species tBu(2)P(Me)C[triple bond]CB(C(6)F(5))(3) (3), tBu(2)P(H)C[triple bond]CB(Cl)(C(6)F(5))(2) (4), tBu(2)P(H)C[triple bond]CB(H)(C(6)F(5))(2) (5), and tBu(2)P(Me)C[triple bond]CB(H)(C(6)F(5))(2) (6) were also prepared. The salt [tBu(2)P(H)C[triple bond]CB(C(6)F(5))(2)(THF)][B(C(6)F(5))(4)] (7) was prepared through abstraction of hydride by [Ph(3)C][B(C(6)F(5))(4)]. Species 5 reacted with the imine tBuN=CHPh to give the borane-amine adduct tBu(2)PC[triple bond]CB[tBuN(H)CH(2)Ph](C(6)F(5))(2) (8). The related phosphine Mes(2)PC[triple bond]CH (9; Mes=C(6)H(2)Me(3)) was used to prepare [tBu(3)PH][Mes(2)PC[triple bond]CB(C(6)F(5))(3)] (10) and generate Mes(2)PC[triple bond]CB(C(6)F(5))(2). The adduct Mes(2)PC[triple bond]CB(NCMe)(C(6)F(5))(2) (11) was isolated. Reaction of Mes(2)PC[triple bond]CB(C(6)F(5))(2) with H(2) gave the zwitterionic product (C(6)F(5))(2)(H)BC(H)=C[P(H)Mes(2)][(C(6)F(5))(2)BC[triple bond]CP(H)Mes(2)] (12). Reaction of tBu(2)PC[triple bond]CB(C(6)F(5))(2), a phosphine-borane generated in situ from 5, with 1-hexene gave the species [tBu(2)PC[triple bond]CB(C(6)F(5))(2)](CH(2)CHnBu)[tBu(2)PC[triple bond]CB(C(6)F(5))(2)] (13) and subsequent reaction with methanol or hexene resulted in the formation of [tBu(2)P(H)C[triple bond]CB(C(6)F(5))(2)](CH(2)CHnBu)[tBu(2)PC[triple bond]CB(C(6)F(5))(2)](OMe) (14) or the macrocycle {[tBu(2)PC[triple bond]CB(C(6)F(5))(2)](CH(2)CH(2)nBu)}(2) (15), respectively. In a related fashion, the reaction of 13 with THF afforded the macrocycle [tBu(2)PC[triple bond]CB(C(6)F(5))(2)](CH(2)CHnBu)[tBu(2)PC[triple bond]CB(C(6)F(5))(2)][O(CH(2))(4)] (16), although treatment of tBu(2)PC[triple bond]CB(C(6)F(5))(2) with THF lead to the formation of {[tBu(2)[triple bond]CB(C(6)F(5))(2)][O(CH(2))(4)]}(2) (17). In a related example, the reaction of Mes(2)PC[triple bond]CB(C(6)F(5))(2) with PhC[triple bond]CH gave {[Mes(2)PC[triple bond]CB(C(6)F(5))(2)](CH[triple bond]CPh)}(2) (18). Compound 5 reacted with AlX(3) (X=Cl, Br) to give addition to the alkynyl unit, affording (C(6)F(5))(2)BC(H)=C[P(H)tBu(2)](AlX(3)) (X=Cl 19, Br 20). In a similar fashion, 5 reacted with [Zn(C(6)F(5))(2)]⋅C(7)H(8), [Al(C(6)F(5))(3)]⋅C(7)H(8), or HB(C(6)F(5))(2) to give (C(6)F(5))(3)BC(H)=C[P(H)tBu(2)][Zn(C(6)F(5))] (21), (C(6)F(5))(3)BC(H)=C[P(H)tBu(2)][Al(C(6)F(5))(2)] (22), or [(C(6)F(5))(2)B](2)HC=CH[P(H)tBu(2)] (23), respectively. The implications of this reactivity are discussed.

Fluorinated antimony(v) derivatives: strong Lewis acidic properties and application to the complexation of formaldehyde in aqueous solutions

“…The presence of the Sb–F(12) interaction is further supported by the fact that the Sb–C(21)–C(22) and Sb–C(31)–C(36) angles involving the other two C 6 F 5 groups are much closer to 120° (119.94(16) and 120.66(16)°, respectively). While similar interactions have been observed in group 13 and 14 compounds, 40–48 such short contacts are not observed in other known C 6 F 5 -decorated antimony( v ) compounds, including Sb(C 6 F 5 ) 5 . 37,49 …”

Frustrated Lewis Pair Chemistry: Development and Perspectives

“…Reaction with PhC CH gave the macrocyclic product [(Mes 2 PC CB-(C 6 F 5 ) 2 )(CH = CPh)] 2 (385; Scheme 111). [169] Compound 373 also reacted with AlX 3 (X = Cl, Br), Zn(C 6 F 5 ) 2 ·C 7 H 8 , Al(C 6 F 5 ) 3 ·C 7 H 8 , or HB(C 6 F 5 ) 2 affording addition to the alkynyl unit to give (C 6 F 5 ) 2 …”

“…In the first study, [169] the reaction of the phosphine t Bu 2 PC CH with B(C 6 F 5 ) 3 afforded the zwitterionic species t Bu 2 P(H)C CB(C 6 F 5 ) 3 (371; Scheme 109 [169] The related phosphine-borane Mes 2 PC CB(C 6 F 5 ) 2 (382) was generated in a similar reaction, although it was only isolable as an acetonitrile adduct Mes 2 PC CB(NCMe)-(C 6 F 5 ) 2 (383). Nonetheless, 382 reacts with H 2 to give the dimeric zwitterionic product (C 6 F 5 ) 2 (H)BHC=C(P(H)Mes 2 )-((C 6 F 5 ) 2 BC CP(H)Mes 2 ) (384; Scheme 111).…”

“…[169] In a similar fashion, the Ni complexes, [( t Bu 2 PC CB-(C 6 F 5 ) 2 )Ni(COD)] (391) and [{( t Bu 2 PC CB(C 6 F 5 ) 2 )Ni-(NCMe)} 2 ] (392) were derived from the reaction of 373 and [Ni(COD) 2 ] (Scheme 113). [171] Similar to that observed in the Zr complex 247, these complexes exhibit metal-alkyne interactions in which the borane substituent bends towards the metal affording a Ni!B dative interaction.…”

Formation of Active Cyclic Five‐membered Frustrated Phosphane/Borane Lewis Pairs and their Cycloaddition Reactions

“…[26] In the presents tudy,w e have made use of the high tendency of the intramolecular hydrocarbyl-bridged frustrated phosphorus/boron Lewis pairs to undergo either typeo fs uch cycloaddition reactions. [9,19,27] Consequently,h eterocyclic products wereo btained in quite some variation upon treatment of the reactive cyclic P/B-FLPs 11 Scheme10. Formation of the two-foldFLP cycloaddition product 27 b and its reaction product with dihydrogen.…”