The method of synthesis has been developed and dinitrosyl iron complexes of a new class (DNIC) have been obtained, which contain functional sulfur-containing ligands and are mimetics of the active sites of nitrosyl non-heme proteins. The structure of cationic, neutral and anionic forms of paramagnetic mononuclear, diamagnetic binuclear of μ-S type and paramagnetic of μ-S-CN type nitrosyl complexes has been studied. Based on precision X-ray data and quantum-chemical calculations, specific features of the electronic structure of the basic (NO)2Fe- unit of these complexes have been studied, as well as the influence of the ligand surrounding on NO donating properties and mechanism of decomposition of the complexes in various solvents at different pH values of the solutions. The obtained results open possibilities for the development of promising medicines on their base, i.e., NO donors for the therapy of socially relevant diseases [1]. In some paramagnetic mononuclear cationic DNIC absolutely unusual magnetic properties have been detected, which cannot be explained in the frame of usual spin model The performed calculation shows a considerable contribution of unquenched orbital moment of the NO group in the magnetic properties of these complexes, which is also responsible for the residual magnetism of diamagnetic anionic DNIC of μ-S type. Specific features of the crystalline and molecular structure of DNIC, which are responsible for orbital paramagnetism have been studied. Bi-nuclei paramagnetic DNIC of μ-S-C-N type having a Heisenberg dimer structure and characterized by antiferromagnetic intramolecular exchange appeared to be promising compounds, which at low temperature possess quantum-information correlations in the form of quantum entanglement of the two-qubit model. The possibility has been shown for these complexes to determine the magnitude of these quantum-information correlations from the magnitude of magnetic susceptibility. The obtained results open prospects for molecular electronics [2] and magnet-controlled target delivery of medicines.