Synthesis of Optically Pure Helicene Metallocenes

Abstract

Tw ot ypes of ruthenocenes and af errocene coordinated by rac-9H-cyclopenta[1,2-c:4,3-c']diphenanthrenyl anion(s), a[ 7]helicene with ac yclopentadienyl moiety at the center of its skeleton, were successfully synthesized:m onohelicene ruthenocene 1 and its iron analogue 1 Fe with one [7]helicene ligand bound to the central metal, and bis-helicene ruthenocene 2 with two [7]helicenes.S tarting from ar acemic mixture of the ligand precursor,r ac-2 and meso-2 were obtained in a7 :3 ratio.S ince the [7]helicene has ah igh racemization barrier,e nantiomers of the complexes were isolated in their pure forms;they showed large optical rotations and intense circular dichroism (CD) responses.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.