Berkelium and californium organometallic ions

Organoberkelium and organocalifornium ions were produced for the first time by laser ablation of (Bk2O3)-Bk-249 and (Cf2O3)-Cf-249 dispersions in poly imide, followed by analysis with time-of flight mass spectrometry. The prim ary products formed were: BkCH3+, BkC2+, AnC(2)H(+), AnCN(+), AnC(4)H(+), A n(OH)(CN)(+), AnOCN(+), AnOH(+), An(OH)(2)(+) and AnO(+) (where An = Bk or Cf). Several of these complexes represent the first organoactindes in which Bk and Cf are directly bonded to carbon. The compositions and abundance di stributions of the products are effectively evaluated in the context of a b onding model which requires one or two non-5f valence electrons at the An() center for participation in direct An(+)-C bonding to form the monovalent or divalent complexes. Both Bk and Cf exhibit a propensity to form. "monov alent" organoactinides in which the metal center forms a single sigma -type bond to the organic moiety. Most earlier actinides form "divalent" complex es having two An+-C bonds. A few small oxide cluster ions, An(m)O(n)(+) (m = 2 or 3) were identified, demonstrating the feasibility of preparing clust ers for the heavy actinides. The energetics underlying the present results are discussed with an emphasis on the evidently pivotal position of Bk in t he actinide series.