Toward new organometallic architectures: synthesis of carbene-centered rhodium and palladium bisphosphine complexes. stability and reactivity of [PC(BIm)PRh(L)][PF6] pincers

Andriy Plikhta; Alexander Pöthig; Eberhardt Herdtweck; Bernhard Rieger

doi:10.1021/acs.inorgchem.5b01428

Toward new organometallic architectures: synthesis of carbene-centered rhodium and palladium bisphosphine complexes. stability and reactivity of [PC(BIm)PRh(L)][PF6] pincers

Inorg Chem. 2015 Oct 5;54(19):9517-28. doi: 10.1021/acs.inorgchem.5b01428. Epub 2015 Sep 21.

Authors

Andriy Plikhta¹, Alexander Pöthig¹, Eberhardt Herdtweck¹, Bernhard Rieger¹

Affiliation

¹ WACKER-Lehrstuhl für Makromolekulare Chemie & Catalysis Research Center, Technische Universität München , Lichtenbergstraße 4, 85748 Garching b. München, Germany.

PMID: 26390389
DOI: 10.1021/acs.inorgchem.5b01428

Abstract

In this article, we report the synthesis of a tridentate carbene-centered bisphosphine ligand precursor and its complexes. The developed four-step synthetic strategy of a new PC(BIm)P pincer ligand represents the derivatization of benzimidazole in the first and third positions by (diphenylphosphoryl)methylene synthone, followed by phosphine deprotection and subsequent insertion of a noncoordinating anion. The obtained ligand precursor undergoes complexation, with PdCl2 and [μ-OCH3Rh(COD)]2 smoothly forming the target organometallics [PC(BIm)PPdCl][PF6] and [PC(BIm)PRh(L)][PF6] under mild hydrogenation conditions. A more detailed study of the rhodium complexes [PC(BIm)PRh(L)][PF6] reveals significant thermal stability of the PC(BIm)PRh moiety in the solid state as well as in solution. The chemical behavior of 1,3-bis(diphenylphosphinomethylene)benzimidazol-2-ylrhodium acetonitrile hexafluorophosphate has been screened under decarbonylation, hydrogenation, and hydroboration reaction conditions. Thus, the PC(BIm)PRh(I) complex is a sufficiently stable compound, with the potential to be applied in catalysis.