Non-palindromic (C^C^D) gold(iii) pincer complexes are not accessible by intramolecular oxidative addition of biphenylenes – an experimental and quantum chemical study

Abstract

We herein report on the synthesis of biphenylenes substituted with a pyridine (N), a phosphine (P) and a carbene (C’) donor as well as a carbene donor with additional pyridine...

Tin-Free Synthesis of 2,2′-Biphenyl Gold(III) Complexes Using Dibenzosilol

“…rely on the dibenzostannol route in order to access sets of LAu­(bph)­Cl complexes. ,, This demonstrates that for screenings, it is more convenient and effective to add a library of ligands to a single gold precursor, instead of preparing all corresponding LAu­(I)Cl complexes followed by oxidative addition to biphenylene. Recently, it was also reported that the attempted directed oxidative addition to a biphenylene derivate failed to give (C ∧ C ∧ D)­Au­(III) complexes, while a stannane-based synthesis has been successfully implemented for the synthesis of highly luminescent tridentate (C ∧ C ∧ D)­Au­(III) complexes …”

“…Recently, it was also reported that the attempted directed oxidative addition to a biphenylene derivate failed to give (C ∧ C ∧ D)Au(III) complexes, 15 while a stannane-based synthesis has been successfully implemented for the synthesis of highly luminescent tridentate (C ∧ C ∧ D)Au(III) complexes. 16 While the bph-tin species can be isolated under air, 10b organotin compounds are known to degrade by light and atmospheric oxygen over time, complicating their storage and handling.…”

Chelation-assisted C–C bond activation of biphenylene by gold(i) halides

“…However, recent work by Breher and co-workers showcased the difficulty of achieving such a transformation. 10 …”

“… 14 The choice of a neutral weakly bound gold( i )-iodide precursor is key for a successful reaction outcome: similar reactions in the presence of [(NHC)AuCl + AgSbF 6 ] failed to deliver the desired biscyclometalation adducts, as reported by Breher et al in ref. 10 . The oxidative insertion of gold( i ) iodide into the four-membered ring of pyridino-substituted biphenylene provides a novel and synthetically efficient entry to κ 3 -(N^C^C)gold( iii ) halides.…”

“…Despite numerous attempts to promote the C–C activation in these complexes, 10,13 all reactions resulted in the formation of highly stable cationic species 11a–b and 12 , which could be easily isolated from the reaction media. In the case of cationic mononuclear-gold( i ) complexes 11 , a ligand scrambling reaction in which the chloride ligand is replaced by a phosphine in the absence of a scavenger, a process previously described for gold( i ) species, can be used to justify the reaction outcome.…”