Synthesis and Characterization of Novel Guanidine Ligands Featuring Biphenyl or Binaphthyl Backbones

Abstract

AbstractIn this paper we report on the synthesis and characterization of several new 2,2′‐bisguanidino‐1,1′‐biphenyl and ‐binaphthyl ligands as well as the electron donor 3,3′,4,4′‐tetrakis(tetramethylguanidino)‐1,1′‐biphenyl. Chiral bisguanidine ligands were prepared with binaphthyl backbones. The solid‐state structures were analysed by single‐crystal X‐ray diffraction. UV/Vis and Raman spectra provided a qualitative insight into the rotational barriers in solution and in the solid state. Finally, late‐transition‐metal complexes of two of these ligands were prepared. These complexes prefer a κ1 rather than a κ2 coordination mode. The discussion of the experimental results is complemented by quantum chemical (DFT) calculations. Finally, we report on the first catalytic test reactions.