Dibenzometallacyclopentadienes, boroles and selected transition metal and main group heterocyclopentadienes: Synthesis, catalytic and optical properties

Selective Synthesis of Stannoles by 1,1‐Carboboration of Bis(trimethylsilylethynyl)tin Compounds Using Weakly and Strongly Electrophilic Triorganoboranes: Characterization of a Zwitterionic Intermediate

“…There is increasing interest in metalloles because of their photophysical properties related to the tuneable band gap of the π system. [1,2] In this context, stannoles deserve attention as electron-rich cyclic dienes and potential starting materials for the synthesis of other metalloles. However, there are rather few straightforward routes available for their preparation, [3] and the majority of the more convenient synthetic strategies appear to be limited to aryl groups at the 2-5 positions.…”

“…[9] In contrast, 1,1-carboboration using triphenylborane, BPh 3 , has led to mixtures of stannoles and 1,4-stannaboracyclohexa-2,5-diene derivatives. [9] In addition, the use of tris(pentafluorophenyl)borane, B(C 6 F 5 ) 3 , for the 1,1-carboboration of R 1 2 Sn(CϵC-R) 2 (R 1 = alkyl, Ph; R = H, nBu) selectively affords 1,4-B, 13 C, 19 F, 29 Si, 119 Sn NMR) was used to characterize the intermediates and the stannoles as the final products. Some of the NMR parameters ( 11 B, 13 C, 29 Si) of the intermediates were calculated by DFT methods using the optimized gas-phase geometries.…”

“…In this work, we studied the 1,1-carboboration reactions of four bis(trimethylsilylethynyl)diorganotin compounds 3 [R 1 2 Sn(CϵC-SiMe 3 ) 2 with R 1 2 = -(CH 2 ) 5 -, (a); R 1 = nBu, (b), n Oct (c), Ph (d)] with triorganoboranes BEt 3 , BPh 3 , and B(C 6 F 5 ) 3 , which differ greatly in their electrophilic character. Previous work on the synthesis of 2 and related stannoles with Me 3 Si groups [6,8] had revealed no evidence for reactive intermediates, and it was hoped that more electrophilic triorganoboranes could be helpful in this respect.…”

Reductive Coupling of Diynes at Rhodium Gives Fluorescent Rhodacyclopentadienes or Phosphorescent Rhodium 2,2’‐Biphenyl Complexes

“…Synthesis of M(2,2'-bph) complexes (bph = biphenyl) as MC4 analogues can be achieved, e.g., by insertion of a low-valent, electron-rich transition metal fragment into a C-C bond of biphenylene or via reaction of a 2,2´-dilithiated biphenyl with a metal dihalide (Scheme 1). [3] These methods clearly limit the range of accessible substituted 2,2´-bph complexes, and hence photophysical studies have been performed on only a small number of transition metal biphenyl compounds of Pd, Pt, Ir and Au. [4] These few examples exhibit phosphorescence with quantum yields of 0.01-0.16, but attempts to improve their performance have not been reported.…”

BN‐Phenanthrin: Cyclotetramerisierung eines 1,2‐Azaborinderivats

“…Wir kamen zu dem Schluss, dass 1,2-Azaborine durch N 2 -Abspaltung und Ringerweiterung von Azidoborolen erzeugt werden kçnnten, da frühere Arbeiten von Paetzold nahelegen, dass sich acyclische Azidodiorganylborane R 2 BN 3 thermisch ohne intermediäre Bildung der Borylnitrene R 2 BN zu Iminoboranen RBNR umlagern. [8,9] Da Azidoborole nicht bekannt und vermutlich hochgradig instabil sind, [10] untersuchten wir die thermische Zersetzung des Dibenzoderivats 9-Azido-9-borafluoren 5. Diese Verbindung wurde schon zuvor in unserer Gruppe synthetisiert und als ziemlich labil eingestuft.…”