title: Does a reinforced kinetic macrocyclic effect exist? the demetallation in strong acid of copper(II) Complexes with open and cyclic tetramines containing a piperazine fragment.
abstract: The demetallation in acidic solution of the Cu(II) complexes with open-chain and cyclic tetramines containing a piperazine unit (2 and 3) has been investigated in terms of its kinetic aspects and compared with the behaviour of unsubstituted counterparts (tetramines 1 and 4). The presence of the piperazine fragment slows demetallation of the open-chain-ligand complex owing to the activation barrier associated with the conformational change from boat-to-half-boat; however, it does not affect the demetallation of the macrocyclic complex, which involves the spontaneous boat-to-twist conformational change. Thus, lateral reinforcement of a cyclam-like ligand does not add any further contribution to the typical inertness in demetallation of macrocyclic complexes.
authors.affiliation: Dipartimento di Chimica Generale, Università di Pavia, via Taramelli 12, 27100 Pavia, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Boiocchi
authors.forename: Marco
authors.initials: M
authors.lastname: Bonizzoni
authors.forename: Luigi
authors.initials: L
authors.lastname: Fabbrizzi
authors.forename: Francesco
authors.initials: F
authors.lastname: Foti
authors.forename: Maurizio
authors.initials: M
authors.lastname: Licchelli
authors.forename: Antonio
authors.initials: A
authors.lastname: Poggi
authors.forename: Angelo
authors.initials: A
authors.lastname: Taglietti
authors.forename: Michele
authors.initials: M
authors.lastname: Zema