Performing Organic Chemistry with Inorganic Compounds: Electrophilic Reactivity of Selected Nitrosyl Complexes

Abstract

The inorganic nitrosyl (NO(+)) complexes [Fe(CN) 5NO](2-), [Ru(bpy)2(NO)Cl](2+), and [IrCl 5(NO)](-) are useful reagents for the nitrosation of a variety of organic compounds, ranging from amines to the relatively inert alkenes. Regarding [IrCl 5(NO)](-), its high electrophilicity and inertness define it as a unique reagent and provide a powerful synthetic route for the isolation and stabilization of coordinated nitroso compounds that are unstable in free form, such as S-nitrosothiols and primary nitrosamines. Related to the high electrophilicity of [IrCl 5(NO)](-), an unusual behavior is described for its PPh 4(+) salt in the solid state, showing an electronic distribution represented by Ir(IV)-NO(*) instead of Ir (III)-NO(+) (as for the K(+) and Na(+) salts).

Complete and Partial Electron Transfer Involving Coordinated NOx

“…Apparently, there is enough charge provided by these potent donors in order to cause significant nitrosyl bending despite the presence of a formal positive charge. Significant structural deviation of the MNO angle from linearity in NO + complexes may also occur due to solid-state packing effects and NO radical involving contributions, as has been discussed for various cases (X + ) [Ir(NO) Cl 5 ] with different cations X + and Ir III (NO + ) $ Ir IV (NO • ) limiting structures (7). The readiness of the originally linear Ru II (NO + ) entity to undergo bending has its origin in the theoretically derived admixture of the Ru III (NO • ) valence isomer even in the ground state (30).…”

“…Corresponding metal-to-ligand charge transfer (MLCT) transitions occur but have rather low intensity (10). An important aspect of the chemistry of cationic and electrophilic (7) NO + is the + III oxidation state of N, corresponding to that of the nitrite anion, NO 2 À (cf. Section 4).…”

Electronic structures and reactivity aspects of ruthenium–nitrosyls

“…The biological relevance of nitrosyl molecule (NO) in neuro-signaling [1], cardiovascular control [2], or in defense mechanisms against microorganisms and tumor cells [3][4][5][6] has prompted an intense renewed research interest towards nitrosyl coordination chemistry [7][8][9][10][11][12][13][14][15]. At the cellular level, NO is produced from L-arginine catalyzed by NO synthase (NOS) and its deficiency initiates a wide range of physiological disorders [16].…”

“…Moreover, the redox non-innocent feature of the coordinated nitrosyl function, cationic NO + , radical NO Å , or anionic NO À [23][24][25][26] makes it an attractive ligand from a broader perspective of inorganic chemistry [7][8][9][10][11][12][13][14][15]. This indeed introduces an extensive research initiative in recent years on newly designed metal-nitrosyl species [(AL){M-NO}] with AL (= ancillary ligands) having varying electronic nature.…”

Conformational and structural diversity of iridium dimethyl sulfoxide complexes

“…Consequently, the first step in this reaction is the formation of a labile N-nitroso intermediate; this is then transformed into the corresponding free alcohol after a second nucleophilic attack by a hydroxyl anion generated during the reaction. Finally, the alcohol is lost from the complex and replaced by a solvent molecule, which, in this case, is DMSO (Di Salvo et al, 2008;Doctorovich & Di Salvo, 2007). The complex now contains one DMSO ligand, and this may exert a higher trans effect than that of the N-nitroso moiety on the trans-chloride, resulting in loss of the corresponding chloride and coordination of a DMSO molecule to the metal centre.…”