Isostructural triazenido complexes of first row transition metals. Part 3. Low spin cyclopentadienyl complexes of cobalt(II) (?5-C5H5)(PPh3)(RN3R)Co

Abstract

Reaction of (PPh3)2Cl2CoII with TlC5H5 gave the new (η5-C5H5)(PPh3)ClCoII complex. This complex reacted with Ag(RN3R) or Cu(RN3R) (R=p-MeC6H4,p-ClC6H4 or 3,5-Cl2C6H3) to give the novel compounds (η5-C5H5)(PPh3)(RN3R)CoII, with a spin state of one half, which are representatives of the very small class of paramagnetic monocyclopentadienyl transition metal complexes. The structural conclusions are based on comparison with the isostructural [η5-C5H5)(PPh3)(RN3R)CoIII]PF6 complex, on the i.r. spectra and on the observed redox behaviour. The e.p.r. spectra are reported, but are not well enough resolved for the determination of the hyperfine interactions. The orbital scheme of the new complex is discussed in terms of a distorted octahedral crystal field in relation to the series of isostructural (η5-C5H5)(PPh3)(RN3R)MII (M = Fe, Co or Ni) complexes.