Acknowledgment. This work was supported by NSF Latin/American Cooperative Science Grant INT-8111977 (to RAA) and by a grant from CNPq (Brazil) (to JM), for which we are grateful. ... Registry No. 1 (X = H), 105019-32-7; 1 (X = Cl), 105019-34-9; 1 (X = NOz), 105019-36-1; 2 (X