The chemistry of donor-functionalized cyclopentadienyl metal carbonyl anions is a research focus of the Fischer group.  Novel intramolecular hydrogen bonds involving group VI metal acceptors in zwitterionic (2-(dimethylammonium)ethyl)cyclopentadienyltricarbonylmetalates, M(CO)₃(Cp^NH) (M = Cr, Mo, W) prompted us to explore methylation of (2-(dimethylamino)ethyl)cyclopentadienyl group VI metal carbonyl anions in the hopes of selective attack at the amine resulting in zwitterionic (2-(trimethylammonium)ethyl)cyclopentadienyltricarbonylmetalates, M(CO)₃(Cp^NMe).  Reactions of CH₃I and these anions resulted in metal alkyls; addition of excess CH₃I led to doubly methylated salts [M'CH₃(CO)₃(Cp^NMe)]I (M' = Mo, W).  These results suggested that a protecting group was necessary for the metal to permit selective methylation of the amine, and the pursuit of this hypothesis was our objective in summer 2006.  Oxidation of Na[M(CO)₃(Cp^N)] with iodine provides MI(CO)₃(Cp^N); subsequent methylation affords structurally characterized [MI(CO)₃(Cp^NMe)]I.  Reduction of these salts provides structurally characterized (2-(trimethylammonium)ethyl)cyclopentadienyltricarbonylmetalates.  The spectroscopic and structural properties of these zwitterions, and their nucleophilicity, will be discussed.