An unusual (10,3)-a racemic twofold interpenetrating network assembled from isolable tris(cyclopentadienyl)manganate and cesocene building blocks

The syntheses and X-ray crystal structures of (18]crown-6)2Cs](+)-Cp3Mn]- (1), (18]crown-6)2Cs](+)-Cp'3Mn]- (2), CsCp'] (3), (CsCp')2-(18]crown-6)] (4), and CsMnCp3] (5), and the synthesis of CsMnCp'3] (6) are reported (Cp' = C5H4Me). The anions Cp3Mn]- (1-) and Cp'3Mn]- (2-) are characterized by eta 2 coordination of all three Cp or Cp' rings. Measurements of the magnetic susceptibilities chi M resulted in values of mu eff = 6.20 microB (300 K), mu eff = 6.33 microB (301 K), and mu eff = 5.83 microB (300 K) for 1, 2, and 5, respectively, which are indicative of high-spin d5-Mn2+ centers. Density functional calculations illustrate that the coordination mode of 1- is characteristic for its sextet electronic ground state. Compound 3 forms infinite chains of cesocene-type sandwiches in the solid state, which are broken up into small subunits by the addition of crown ether to form 4. Compound 5 is a rare example of a (10,3)-a racemic interpenetrating network that crystallizes in the orthorhombic space group Pbca.