Synthesis and Structures of (Porphinato)(thiolato)gallium(III) Complexes

Abstract

Gallium(III)-substituted P-450 models, [Ga(OEP)(SAr)] (OEP=octaethylporphinato; SAr=S-2-CF3CONHC6H4, SPh), were synthesized and the structures were determined by X-ray analysis. The gallium(III) complexes were found to be excellent structural analogues having a diamagnetic metal center.

Synthesis and molecular structures of S-2-FcNHCOC6H4SH and [MIII(OEP)(S-2-FcNHCOC6H4)] (Fc = ferrocenyl, M = Fe, Ga): Electrochemical contributions of intramolecular SH⋯O C and NH⋯S hydrogen bonds

“…These values were found in a reasonable region for 5-coordinated porphinato(thiolato) compounds reported previously [14]. Furthermore, paramagnetic iron(III) center effectively shifts the proton signal by electron spin-nuclear spin interactions through bonds and/or space.…”

“…The NH stretching band of 3a was found at a lower wavenumber (3184 cm À1 ) than that of 2a (3195 cm À1 ). Such a stronger NHÁ Á ÁS has been found previously, which is caused by a more ionic Ga-S bond than Fe-S [14]. The ionic bond prevents the decrease of electron density on S by p-donation from the thiolato ligand to the metal ion and the electron-rich sulfur has considerably strong ability of hydrogen bond formation.…”

“…The degree of electron donation depends on the M-S bond character. Ionic Ga-S bond tends to remain the electron on sulfur but the relatively covalent Fe-S bond uses the electrons for the linkage [14]. The found tendency of hydrogen bond strength, 4a > 2a > 3a, is a reasonable result.…”

“…The selected bond lengths and angles are summarized in Table 1 comparing with some analogous. Two structures of (porphinato)gallium(III) thiolate complexes have been known [14]. Previously, we reported a significant contribution of intramolecular NHÁ Á ÁS hydrogen bond to the elongation of Ga-S bond.…”

Conformational Switching Between Acids and their Anions by Hydrogen Bonding

“…In contrast, the FeÀS bond distance in P450 model porphyrin complexes slightly elongates with NHÁ Á ÁS hydrogen bonding, as it does for the similar Ga(III) complex [55,56]. IR shifts for [Fe III (OEP)(S-tBuCONHC 6 H 4 )] (OEP ¼ octaethylphorphinato) and [Ga III (OEP)(S-t-BuCONHC 6 H 4 )] indicate the presence of a relatively weak NHÁ Á ÁS hydrogen bond.…”