Conformational analysis of octa- and tetrabromo tetraphenylporphyrins and their Ni(II) and Tb(III) complexes.
Molecular mechanics (MM) calculations were used to analyze the puckering of metalloporphyrins as a function of metal ion size and the position of substituents on the porphyrin periphery, on a three series of octa- and tetrabromo tetraphenylporphyrins: without metal, and with Ni(II), and Tb(III) as representative small and large metal ions, respectively. Molecular energy optimization calculations were carried out using the Consistent Force Field (CFF) program, with the parameters developed previously and new parameters for bromine atom. Normal-coordinate structural decomposition (NSD) analysis was performed on the equilibrium structures obtained by MM calculations. The conformers are also stereochemically characterized, compared with available X-ray structures and with the conformers obtained in our previous MM study using chloro instead of bromo beta-pyrrole substituents.
Chemistry Department, University of Belgrade, Studentski Trg 16, P.O. Box 158, YU-11001 Belgrade, Serbia and Montenegro; Center for Chemistry, IHTM, YU-11001 Belgrade, Serbia and Montenegro.
Maja
M
Gruden-Pavlović
Sonja
S
Grubisić
Svetozar R
SR
Niketić