Synthesis and characterization of xylene-based group-six metal PCP pincer complexes

Wolfgang Eder,Berthold Stöger,Karl Kirchner

doi:10.1007/s00706-019-02422-6

Abstract

In the present study, the Cr(III) complex trans-[Cr(PCPCH2-iPr)(CH3CN)(Br)2] as well as seven-coordinate cationic bromo carbonyl Mo(II) and W(II) complexes of the type [M(PCPCH2-iPr)(CO)3Br] (M=Mo, W) featuring PCP pincer ligands based on a xylene scaffold were prepared and characterized. The seven-coordinate bromo tricarbonyl complexes exhibit fluxional behavior in solution due to rapid CO ligand interconversions. The mechanism of this process was studied by means of DFT calculations. Structures of representative complexes were determined by single-crystal X-ray analyses.Graphical abstract

Highlights

PCP pincer complexes which feature an aromatic anionic benzene backbone connected to phosphine donors via CH2, O, or NR (R=H, alkyl, aryl) linkers are a very attractive class of compounds [1,2,3]
We utilize the oxidative addition of the C–Br bond of the ligand precursor (2-bromo-1,3-phenylene)bis(methylene) bis(diisopropylphosphane) (P(C-Br)PCH2-iPr) (1) to the hexacarbonyl complexes [M(CO)6] (M=Cr, Mo, W) as synthetic entry into group-six metal PCP pincer complexes
All CO ligands are involved in interchange processes that occur in single-step paths

Summary

Introduction

PCP pincer complexes which feature an aromatic anionic benzene backbone connected to phosphine donors via CH2, O, or NR (R=H, alkyl, aryl) linkers are a very attractive class of compounds [1,2,3]. Keywords Chromium · Molybdenum · Tungsten · Pincer complexes · Carbonyl ligands · DFT calculations We utilize the oxidative addition of the C–Br bond of the ligand precursor (2-bromo-1,3-phenylene)bis(methylene) bis(diisopropylphosphane) (P(C-Br)PCH2-iPr) (1) to the hexacarbonyl complexes [M(CO)6] (M=Cr, Mo, W) as synthetic entry into group-six metal PCP pincer complexes.

Results

Conclusion