Synthesis and structure of planar-chiral (1,2,4-trisubstituted cyclopentadienyl)cobalt(tetraarylcyclobutadiene) complexes containing three different chiralities in one molecule

Article abstract of DOI:10.1016/0022-328X(94)80131-2

The first diastereomerically pureplanar-chiral cyclopentadienyl-cobalt complexes (4 and 5) have been synthesised by the reaction of CoCl(PPh3)3 with a trisubstituted cyclopentadienyl anion having a (-)-menthyl group in the presence of diarylacetylenes.Removal of the menthyl group from 4a and 5a afforded the first optically pure enantiomers of planar-chiral cyclopentadienylcobalt complexes, (+)- and (-)-6, and (+)- and (-)-7.The molecular structure including absolute configuration of 4a has been established by a single-crystal X-ray structure analysis.Crystallographic data for 4a: orthorhombic, space group P2₁2₁2₁; a = 18.602(10), b = 15.629(3), c = 13.893(3) Angstroem; Z = 4; R = 0.051, R_w = 0.057.The structure of 4a indicates that there exist three different chiralities , and helical (C4Ar4-moiety) chirality> in one molecule.These complexes provide not only the first optically pure planar-chiral Cp'-Co omplexes but also the first examples containing three different chiralities in one molecule. Key words: Cobalt, Cyclobutadiene; Optical resolution; X-ray diffraction; Crystal structure