RT Journal Article
T1 Copper(II) Complexes of Cyclams Containing Nitrophenyl Substituents: Push–Pull Behavior and Scorpionate Coordination of the Nitro Group
A1 Boiocchi, Massimo
A1 Ciarrocchi, Carlo
A1 Fabbrizzi, Luigi
A1 Licchelli, Maurizio
A1 Mangano, Carlo
A1 Poggi, Antonio
A1 Vázquez López, Miguel
AB The three nitrophenyl–cyclam derivatives (nitrocyclams): 1-(4-nitrophenyl)-1,4,8,11-tetraazacyclotetradecane (2), 1-(2-nitrophenyl)-1,4,8,11-tetraazacyclotetradecane (3), and 1-(2,4-dinitrophenyl)-1,4,8,11-tetraazacyclotetradecane (4), in an MeCN solution, specifically incorporate the CuII ion according to an irreversible process signaled by disappearance of the yellow color for a concentration c < 1 × 10–4 M and by a yellow-to-red color change for c ≥ 1 × 10–3, and must be considered efficient and specific dosimeters of copper(II) salts. When present in the ortho position of the nitrophenyl substituent, the −NO2 group coordinates the CuII according to a scorpionate mode, while the metallocyclam system exhibits a trans-I configuration. In an MeCN solution the red trans-I-[CuII(3)]2+ and trans-I-[CuII(4)]2+ scorpionate complexes slowly convert into the violet trans-III scorpionate complexes. Kinetic aspects of the trans-I-to-trans-III configurational rearrangement were investigated in detail for the [CuII(4)]2+ system. In particular, the conversion is spectacularly accelerated by catalytic amounts of Cl–, NCO–, and F–. While for Cl– and NCO– the effect can be associated with the capability of the anion to stabilize through coordination a possible dissociative intermediate, the amazingly powerful effect of F– must be related to the preliminary deprotonation of one N–H fragment of the macrocycle, driven by the formation of the HF2– ion. Most of the metal complex species studied in solution were isolated in a crystalline form, and their molecular structures were elucidated through X-ray diffraction studies. This study documents the first examples of effective metal coordination by the nitro group
PB American Chemical Society
SN 0020-1669
YR 2015
FD 2015
LK http://hdl.handle.net/10347/17020
UL http://hdl.handle.net/10347/17020
LA eng
NO Massimo Boiocchi, Carlo Ciarrocchi, Luigi Fabbrizzi, Maurizio Licchelli, Carlo Mangano, Antonio Poggi, and Miguel Vázquez López Inorganic Chemistry 2015 54 (21), 10197-10207 DOI: 10.1021/acs.inorgchem.5b01273
NO The financial support of the Italian Ministry of University and Research (PRIN−InfoChem) is gratefully acknowledged
DS Minerva
RD 27 abr 2026