Sodium and Potassium Complexes of Anionic N‐Heterocyclic Carbenes

Abstract

The reaction of 1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene (IDipp) with n‐BuLi in the presence of sodium and potassium bis(trimethylsilyl)amide was studied, and the resulting polymeric dicarbene species were reacted with the fluoroboranes tris(pentafluorophenyl)borane, B(C6F5)3, and tris[3,5‐bis(trifluoromethyl)phenyl]borane, B(m‐XyF6)3 to produce sodium and potassium salts of an anionic N‐heterocyclic carbene with a weakly coordinating borate moiety (WCA‐NHC).

Nickelacarborane-Supported Bis-N-heterocyclic Carbenes

“…The bond lengths of Na–C in ( 3a )·[Na­(THF) 4 ] 2 is 261.0(3) pm, which is comparable to those reported for five-coordinated sodium carbene complexes (Table ). However, the Na–C bond lengths in ( 3b )·[Na­(THF) 3 ] 2 is only 246.1(3) pm, as the tetra-coordinated sodium carbene complexes have much shorter Na–C distances than the five-coordinated ones . The average Ni–C cage distances in 3a and 3b are 258.7 and 255.6 pm, respectively, which is almost identical to those in 2 .…”

N‐Heterocyclic Carbenes Carrying Weakly Coordinating Anions

“…For the sodium carbene [(F 5 C 6 ) 3 B‐IDipp]Na(thf) 3 ( 6 g ), IDipp was deprotonated with a mixture of NaHMDS/ n BuLi in Et 2 O and then treated with B(C 6 F 5 ) 3 in toluene, followed by recrystallization from THF (88 % yield). Likewise, deprotonation of IDipp with KHMDS/ n BuLi and subsequent reaction with B(m‐XyF 6 ) 3 yielded [(m‐XyF 6 ) 3 B‐IDipp]K(thf) 3 ( 6 h , 60 % yield) [22] . Furthermore, lithium salts of WCA‐NHCs containing aluminate‐ or gallate‐functionalized backbones were also prepared in our group.…”

“…Likewise, deprotonation of IDipp with KHMDS/nBuLi and subsequent reaction with B(m-XyF 6 ) 3 yielded [(m-XyF 6 ) 3 B-IDipp]K(thf) 3 (6 h, 60 % yield). [22] Furthermore, lithium salts of WCA-NHCs containing aluminateor gallate-functionalized backbones were also prepared in our group. Following the same synthetic strategy as described above, the reaction of the dicarbene 5 with Al(C 6 F 5 ) 3 or Ga(C 6 F 5 ) 3 , furnished the complexes [(F 5 C 6 ) 3 E-IDipp]Li(thf) 2 (6 i: E = Al; 6 j: E = Ga) in 45 and 79 % yields, respectively.…”

Heterobimetallic Coinage Metal‐Ruthenium Complexes Supported by Anionic N‐Heterocyclic Carbenes

“…In search for alternative transmetalation reagents, sodium and potassium salts of WCA‐NHCs were recently introduced, however, their synthesis through deprotonation of IDipp with Schlosser base combinations of sodium or potassium bis‐(trimethylsilyl)amides and n ‐BuLi leaves room for further optimisation. [18] Therefore, we turned our attention to WCA‐NHC complexes of the lighter coinage metals, since silver(I) and as well as copper(I) NHC complexes have become well‐established and widely used carbene transfer reagents. [19] As a result, we present, among other things, the synthesis and characterization of Ag(I) and Cu(I) complexes such as [(WCA‐NHC)M( η 2 ‐toluene)] ( 5 , M=Ag, Cu) and their attempted use for the preparation of ruthenium(II) WCA‐NHC complexes (Figure 1 ).…”

“…Schlosser base combinations of sodium or potassium bis-(trimethylsilyl)amides and n-BuLi leaves room for further optimisation. [18] Therefore, we turned our attention to WCA-NHC complexes of the lighter coinage metals, since silver(I) and as well as copper(I) NHC complexes have become well-established and widely used carbene transfer reagents. [19] As a result, we present, among other things, the synthesis and characterization of Ag(I) and Cu(I) complexes such as [(WCA-NHC)M(η 2 -toluene)]…”