Novel Type of Tetranitrosyl Iron Salt: Synthesis, Structure and Antibacterial Activity of Complex [FeL’2(NO)2][FeL’L”(NO)2] with L’-thiobenzamide and L”-thiosulfate

Abstract

In this work a new donor of nitric oxide (NO) with antibacterial properties, namely nitrosyl iron complex of [Fe(C6H5C-SNH2)2(NO)2][Fe(C6H5C-SNH2)(S2O3)(NO)2] composition (complex I), has been synthesized and studied. Complex I was produced by the reduction of the aqueous solution of [Fe2(S2O3)2(NO)2]2− dianion by the thiosulfate, with the further treatment of the mixture by the acidified alcohol solution of thiobenzamide. Based on the structural study of I (X-ray analysis, quantum chemical calculations by NBO and QTAIM methods in the frame of DFT), the data were obtained on the presence of the NO…NO interactions, which stabilize the DNIC dimer in the solid phase. The conformation properties, electronic structure and free energies of complex I hydration were studied using B3LYP functional and the set of 6–31 + G(d,p) basis functions. The effect of an aquatic surrounding was taken into account in the frame of a polarized continuous model (PCM). The NO-donating activity of complex I was studied by the amperometry method using an “amiNO-700” sensor electrode of the “inNO Nitric Oxide Measuring System”. The antibacterial activity of I was studied on gram-negative (Escherichia coli) and gram-positive (Micrococcus luteus) bacteria. Cytotoxicity was studied using Vero cells. Complex I was found to exhibit antibacterial activity comparable to that of antibiotics, and moderate toxicity to Vero cells.

Synthesis of a tetranitrosyl iron complex with unique structure and properties as an inhibitor of phosphodiesterases

“…In the IR spectra of anionic, 52,62 neutral 50,63 and cationic 64,65 DNICs or their dimers, 66 two intense absorption bands of valence oscillations of NO groups are usually present, which correspond to in-phase (NO- sym ) and antiphase (NO- asym ) oscillations of NO groups. The value of the oscillatory doublet splitting between ν NO- sym and ν NO- asym (Δ ν NO) depends on the nature of the ligands coordinated to the iron atom 67 and, as a rule, is due to the nonequivalence of the nitrosyl groups in the {Fe(NO) 2 } 9 fragments.…”