of the central metal atom (Zn2+ and Cd2+, resp.) on the chemical shifts of the q-C5H5 and OC2H5 signals.
Preliminary experiments have shown that the alkaline earth metal ions Mgz+ and Ca2+ and, surprisingly, Hg2+ are also precipitated with the organometallic chelating agents [C,H,Co{ PO(OC,H,),} 3] -(prepared from {PO(OC2H5)2}3BF]+). Current investigations ought to clarify how selective the precipitation properties of the new chelating agents are and whether in each case (i.e. also with the larger ions) trinuclear complexes are formed in which-as in (la)-the six oxygen atoms of the phosphonato groups are coordinated octahedrally to the central metal atom.
CC,H,CoPO(OC2H,),~P(OH)(OC2H,),~,I+ or IC,H,Co-M2+ '
Experimental:
[C5H5Co{PO(OC2H5)2}3BF]BF4 (125 mg, 0.19mmol) is dissolved in methanol (10 ml) and the resulting solution diluted with water (10ml). 6ml of a 0.02 M aqueous solution of MCI2 or MSO, (M = Mn, Fe, Ni, Cu, Zn, Cd) is now added slowly to the stirred solution. After 30min the precipitate that has formed is filtered off and washed with water until no CIor SO:-, respectively, can be detected in the filtrate. The product is dried in a high vacuum, washed with methanol, re-dried, and finally recrystallized from CCI4. Yield: 40 to 95% (3b)-( ).