As part of our research effort directed at the preparation of volatile organometallic compounds of the group 2 elements Ca, Sr, and Ba,'we needed cyclopentadienide anions exocyclically p-or 'y-substituted with ether or amine functionality capable of intramolecular coordination to the central metal atom. Although many ring-, and a few aexocyclic heteroatom-substituted cyclopentadienes are known? they were not useful to our need ...