Nickel boryl complexes and nickel-catalyzed alkyne borylation

Abstract

The first nickel bis-boryl complexes cis [Ni(iPr2ImMe)2(Bcat)2], cis [Ni(iPr2ImMe)2(Bpin)2] and cis [Ni(iPr2ImMe)2(Beg)2] are reported, which were prepared via the reaction of a source of [Ni(iPr2ImMe)2] with the diboron(4) compounds B2cat2,...

Solution and solid-state studies of hydrogen and halogen bonding with N-heterocyclic carbene supported nickel(ii) fluoride complexes

“…There are three approaches to the study of non-covalent interactions in the crystalline state that are relevant here: the use of ion pairs 28 for charged species, the design of self-complementary molecules 29 and the co-crystallisation of donor and acceptor molecules. 30 To study the halogen bonding of bis(carbene) substituted nickel fluorides, we have performed co-crystallisation experiments with three different complexes, 2-iPr 2 Im , the backbone methylated analogue [Ni(F)(iPr 2 Me 2 Im) 2 (C 6 F 5 )], 2-iPr 2 Me 2 Im 31,32 (iPr 2 Me 2 Im = 1,3-diisopropyl-4,5-dimethyl-imidazolin-2-ylidene), and the mesityl substituted carbene complex [Ni(F)(Mes 2 Im) 2 (C 6 F 5 )], 2-Mes 2 Im (Mes 2 Im = 1,3-dimesityl-imidazolin-2-ylidene). 22 1,4-diiodotetrafluorobenzene (C 6 F 4 I 2 ) was used as a halogen bond donor that could form mono- or dinuclear adducts in 1 : 1 and 1 : 2 stoichiometry.…”

On the Reactivity of a NHC Nickel Bis‐Boryl Complex: Reductive Elimination and Formation of Mono‐Boryl Complexes

“…C 6 D 6 was purchased from Sigma‐Aldrich. i Pr 2 Im Me , [23] cis ‐[Ni( i Pr 2 Im Me ) 2 (Bcat) 2 ] 1 , [18] and [Ni( i Pr 2 Im Me ) 2 (Br) 2 ] [16g] were prepared according to published procedures. The diboron reagent B 2 cat 2 was a generous gift from AllyChem Co. Ltd. All other reagents were purchased from Aldrich or ABCR and used without further purification.…”

“…In the course of our work on the borylation of polyfluorarenes, aryl chlorides, and indoles using synthetic equivalents of the complexes [Ni(Mes 2 Im) 2 ] or [Ni(Cy 2 Im) 2 ] as catalysts (R 2 Im=1,3‐di‐organyl‐imidazolin‐2‐ylidene; Cy=cyclohexyl; Mes=mesityl) we postulated the formation of nickel‐boryl species, which defied isolation [17] . Very recently, we reported the synthesis of novel nickel bis‐boryl complexes cis ‐[Ni( i Pr 2 Im Me ) 2 (B{OR} 2 ) 2 ] ( G ) ({OR} 2 =catecholato ( 1 ), pinacolato, ethylene glycolato) stabilized by monodentate NHC ligands i Pr 2 Im Me ( i Pr 2 Im Me =1,3‐di‐ iso ‐propyl‐4,5‐dimethylimidazolin‐2‐ylidene) [18] . Furthermore, we demonstrated the application of [Ni( i Pr 2 Im Me ) 2 ] as an effective catalyst for the borylation of alkynes, providing interesting new selectivities [18] compared to the well‐established platinum‐phosphine catalyst systems [10c,12] .…”

Catalyst-free diboration and silaboration of alkenes and alkynes using bis(9-heterofluorenyl)s

“… 5 Thus, the most commonly used diboranes(4) today are the commercially available compounds B 2 cat 2 and B 2 pin 2 , which routinely require activation by catalysts ( Scheme 1 ). 6 These can be as diverse as noble metal complexes 7 and plain alkoxide ions. 8 The latter act through tetracoordination of one B center to form B(sp 2 )–B(sp 3 ) diboranes with strongly polarized B–B bonds.…”