The Ruthenium Nitrosyl Moiety in Clusters: Trinuclear Linear μ-Hydroxido Magnesium(II)-Diruthenium(II), μ3-Oxido Trinuclear Diiron(III)-Ruthenium(II), and Tetranuclear μ4-Oxido Trigallium(III)-Ruthenium(II) Complexes.

Iryna Stepanenko,Ghenadie Novitchi,Joshua Telser,Vladimir B Arion,Dominik Schaniel,Lukáš Bučinský,Barbora Vénosová,Pavlo Mizetskyi,Peter Rapta,Geneviève Blondin,Martin Lutz,Yu-Sheng Chen,Martin Clémancey,Michal Zalibera,Ewelina Orlowska,Jozef Kožíšek,Wolfgang Schrader

doi:10.1021/acs.inorgchem.1c03011

Abstract

The ruthenium nitrosyl moiety, {RuNO}6, is important as a potential releasing agent of nitric oxide and is of inherent interest in coordination chemistry. Typically, {RuNO}6 is found in mononuclear complexes. Herein we describe the synthesis and characterization of several multimetal cluster complexes that contain this unit. Specifically, the heterotrinuclear μ3-oxido clusters [Fe2RuCl4(μ3-O)(μ-OMe)(μ-pz)2(NO)(Hpz)2] (6) and [Fe2RuCl3(μ3-O)(μ-OMe)(μ-pz)3(MeOH)(NO)(Hpz)][Fe2RuCl3(μ3-O)(μ-OMe)(μ-pz)3(DMF)(NO)(Hpz)] (7·MeOH·2H2O) and the heterotetranuclear μ4-oxido complex [Ga3RuCl3(μ4-O)(μ-OMe)3(μ-pz)4(NO)] (8) were prepared from trans-[Ru(OH)(NO)(Hpz)4]Cl2 (5), which itself was prepared via acidic hydrolysis of the linear heterotrinuclear complex {[Ru(μ-OH)(μ-pz)2(pz)(NO)(Hpz)]2Mg} (4). Complex 4 was synthesized from the mononuclear Ru complexes (H2pz)[trans-RuCl4(Hpz)2] (1), trans-[RuCl2(Hpz)4]Cl (2), and trans-[RuCl2(Hpz)4] (3). The new compounds 4–8 were all characterized by elemental analysis, ESI mass spectrometry, IR, UV–vis, and 1H NMR spectroscopy, and single-crystal X-ray diffraction, with complexes 6 and 7 being characterized also by temperature-dependent magnetic susceptibility measurements and Mössbauer spectroscopy. Magnetometry indicated a strong antiferromagnetic interaction between paramagnetic centers in 6 and 7. The ability of 4 and 6–8 to form linkage isomers and release NO upon irradiation in the solid state was investigated by IR spectroscopy. A theoretical investigation of the electronic structure of 6 by DFT and ab initio CASSCF/NEVPT2 calculations indicated a redox-noninnocent behavior of the NO ancillary ligand in 6, which was also manifested in TD-DFT calculations of its electronic absorption spectrum. The electronic structure of 6 was also studied by an X-ray charge density analysis.

Highlights

Background and Applications to Isotropic andAnisotropic Dielectrics
The diamagnetism of complex 3 was confirmed by a 1H NMR spectrum, which exhibited sharp resonances in the usual window of chemical shifts for diamagnetic compounds
MeCN/MeOH measured in the negative ion mode showed a peak at m/z 442.89 attributed to [RuIICl2(Hpz)4−H]−

Summary

■ INTRODUCTION

Μ3-Oxido-centered transition metal based triangular complexes form a class of coordination compounds with many members, often exhibiting exciting electronic and magnetic properties.[1−11] The trinuclear μ3-oxido cluster with μ2-carboxylate bridges is a well-known structural type within the broader class of complexes with a [M3(μ3-O)]n+ core. The TZVP basis set is used for calculation of Mössbauer parameters for comparison with the present experiments and EPR parameters for potential future studies (see the Supporting Information) In comparison against DFT results, it can be seen that certain d orbital populations of Fe are overestimated (see Table S12) It is common in experimental studies (as well as in theoretical calculations) of electronic structure[88] that the charge of the central atom is always lower than the formal oxidation state. The observed decomposition of the complex in solution could have its origin in breaking these Fe−Cl bonds

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES