d8 Nickel and palladium difluorocarbenes derived from trifluoromethyl POCOP-type pincer complexes

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

“…Moreover,t his approach is ideally suited to the formation of bridged WCAso ft he type [LA-X-LA] À ,a nd even higher aggregates of bridging species of the type [LA-X-LA-X-LA] À can be formed. [216] [203] (top left) and selected examples of novel B(C 6 F 5 )RR' Lewis acids (right and bottom). [215] Furthermore,f luoride abstraction by B(C 6 F 5 ) 3 from the ( iPr POCOP)Ni(CF 3 )( where iPr POCOP = 2,6-( i Pr 2 PO) 2 -C 6 H 3 )y ields the cationic difluorocarbene complex [( iPr POCOP)Ni = CF 2 ] + .T he formation of the [FB(C 6 F 5 ) 3 ] À ion imparts greater stability towards the highly reactive carbene than the triflate analogue.…”

“…[215] Furthermore,f luoride abstraction by B(C 6 F 5 ) 3 from the ( iPr POCOP)Ni(CF 3 )( where iPr POCOP = 2,6-( i Pr 2 PO) 2 -C 6 H 3 )y ields the cationic difluorocarbene complex [( iPr POCOP)Ni = CF 2 ] + .T he formation of the [FB(C 6 F 5 ) 3 ] À ion imparts greater stability towards the highly reactive carbene than the triflate analogue. [216] [204,205] Angewandte Chemie Reviews Them olecular dimer Al 2 Br 6 has been shown to abstract bromide from tert-butyl bromide to form the room temperature stable [ t Bu][Al 2 Br 7 ]s alt, which has am elting point of 2 8 8C, thus making it ar oom-temperature ionic liquid. [8] Furthermore,A l 2 Br 6 also abstracts bromide from 2-exonorbornyl bromide to yield the 2-norbornyl cation as its [Al 2 Br 7 ] À salt.…”

“…Furthermore, fluoride abstraction by B(C 6 F 5 ) 3 from the ( i Pr POCOP)Ni(CF 3 ) (where i Pr POCOP=2,6‐( i Pr 2 PO) 2 ‐C 6 H 3 ) yields the cationic difluorocarbene complex [( i Pr POCOP)Ni=CF 2 ] + . The formation of the [FB(C 6 F 5 ) 3 ] − ion imparts greater stability towards the highly reactive carbene than the triflate analogue …”

Gold Difluorocarbenoid Complexes: Spectroscopic and Chemical Profiling

“…This effect is evident from the structures of other metal difluorocarbene complexes in the solid state; [14] the net stabilizing function notwithstanding,m ost examples that proved sufficiently stable for isolation in pure form do comprise af airly strongly p-donating central metal fragment. [15] In contrast, cationic difluorocarbene complexes, [16] as well as difluorocarbene complexes of platinum and gold, as the most widely used carbophilic catalysts in synthesis are exceedingly rare. [17,18] Since the poor p-backdonation from [LAu] + in A imparts partial carbocation character onto the ground state of the coordinated carbene ligand, [19] it is also deemed relevant in the present context to recapitulate to which extent fluorine substituents can stabilize carbenium ions ( Figure 1).…”

Nickel‐Mediated Trifluoromethylation of Phenol Derivatives by Aryl C−O Bond Activation

“…[16,26] On the basis of the above experimental results,w e hypothesized that CCl 3 CN served as am ild and effective oxidant for converting ArNi II CF 3 to high-valent ArNiCF 3 species,which subsequently underwent reductive elimination to afford 2-NpCF 3 .T oo ur surprise,t he reaction of 3 and CCl 3 CN in the presence of 2,6-di-tert-butyl-4-methyphenol (BHT) afforded the desired 6a and the unexpected chlorodifluoromethylated product 8 (Scheme 3C). We assumed that 8 was formed through Ni difluorocarbene intermediates, [27] However,t he exact reaction mechanism remains the subject of ongoing studies.F inally,w ew ere pleased to find that the formation of 8 was inhibited when NBu 4 Cl was added to the reaction mixture,a lthough the role of NBu 4 Cl is elusive. Furthermore,the yield of 6awas improved from 86 to 93 %in the presence of NBu 4 Cl (Scheme 3C).…”