Compounds having the formula R-(CH.sub.2).sub.m -CO-R' wherein R is ferrocene, a 5 to 7 member azacyclic system or an 8 to 11 member azabicyclic system, having 1 or 2 nitrogen atoms, or any such system substituted with one or more of F, Cl, Br, OH, C1 to C4 alkyl, C1 to C4 alkoxy, CF.sub.3, phenyl, amino, C1 to C4 alkylamino and di(C1 to C4 alkyl)amino; m is 0 or 1; and R' is--[NH(CH.sub.2).sub.n ].sub.x NH.sub.2, with each n being independently 2 to 5 and x being 1 to 6; ##STR1## with each n being independently 2 to 5, x being 0 to 4, y and z being independently 1 to 5 and the sum of x and the greater of y and z being 1 to 5; or ##STR2## with each a being 2 to 5, each b being 2 to 5, each n being independently 2 to 5, x being 0 to 3, each y being 0 or 1, z being 0 to 3 and x+y+z being 0 to 4, and their pharmaceutically acceptable acid addition salts are potent excitatory amino acid neurotransmitter antagonists. These compounds are useful as mammalian psychotherapeutants, as the active ingredient in pharmaceutical compositions for treating conditions in mammals which are mediated by excitatory amino acid neurotransmitters and in the control of invertebrate pests.