Issue 19, 2017

Hg(ii) and Pd(ii) complexes with a new selenoether bridged biscarbene ligand: efficient mono- and bis-arylation of methyl acrylate with a pincer biscarbene Pd(ii) precatalyst

Abstract

Two equivalents of 1-benzyl-3-bromoethylbenzimidazolium bromide couple with Na2Se to produce the first selenoether bridged bis-benzimidazolium salt (LH2)Br2. The nitrate (LH2)(NO3)2 and tetrafluoroborate (LH2)(BF4)2 salts were also synthesized from (LH2)Br2. The reaction of Hg(OAc)2 with (LH2)Br2 gave the first pseudo pincer carbene mercury complex, [Hg(L2C)][HgBr4] (C1). Different complexes of Pd(II) with selenoether bridged carbene were obtained using (LH2)Br2 and (LH2)(NO3)2. Syntheses of these complexes were dependent on the counter anion and the temperature. Thus, the pincer type ionic complex [PdBr(L3CSeC)]Br (C2) was isolated at 80 °C and the pseudo pincer type neutral complex cis-[PdBr2(L2C)] (C3) was isolated at room temperature from (LH2)Br2 and Pd(OAc)2 in DMSO. The nitrate precursor (LH2)(NO3)2 on palladation with Pd(OAc)2 afforded [Pd(L4CBzCSeC)]NO3 (C4) showing an unprecedented intramolecular metallation at the ortho position of the benzyl wingtip of the benzimidazole moiety. The ligand salts and metal complexes have been characterized using HRMS, heteronuclear NMR and IR spectroscopy. Single crystal X-ray structures of the ligand salts (LH2)Br2 and (LH2)(BF4)2 and complexes C1–C4 have also been elucidated. Complex C2 showed good activity for C–C coupling in the mono-Heck reaction of methyl acrylate and arylbromides. Interestingly, the less common bis-arylation was also observed with deactivated arylbromides as the result of double-Heck coupling.

Graphical abstract: Hg(ii) and Pd(ii) complexes with a new selenoether bridged biscarbene ligand: efficient mono- and bis-arylation of methyl acrylate with a pincer biscarbene Pd(ii) precatalyst

Supplementary files

Article information

Article type
Paper
Submitted
28 Nov 2016
Accepted
07 Apr 2017
First published
11 Apr 2017

Dalton Trans., 2017,46, 6291-6302

Hg(II) and Pd(II) complexes with a new selenoether bridged biscarbene ligand: efficient mono- and bis-arylation of methyl acrylate with a pincer biscarbene Pd(II) precatalyst

Rishu, B. Prashanth, D. Bawari, U. Mandal, A. Verma, A. R. Choudhury and S. Singh, Dalton Trans., 2017, 46, 6291 DOI: 10.1039/C6DT04505G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements