How does the pH influences the Ru‐NO coordination compounds?

Abstract

The pH influence has important role in the bioavailability of coordination compounds.fac-[Ru(NO)Cl 2 (κ 3 N 4 ,N 8 ,N 11 [1-carboxypropyl]cyclam)] + , 1, and the species found at different pHs, 2-4, were investigated. One series of computational methodologies has been used to investigate these compounds. One special highlight is to interacting quantum atoms method, where the total interaction energy, E AB int , between two atoms has been used as base to estimate the chemical bonds strength. The deprotonation ofcreates a hydrogen bond in the complex 2, N(3)-HÁÁÁ ÁOCO − , with a more favorable E AB int than the presents in 1, N(3)-HÁÁÁ ÁOCOH. There are no changes in E AB int in Ru-NO bond. The second deprotonation occurs in the N(2) atom of the cyclam group, 2à3 (pK a = 8.0). It promotes an increase in the covalent character of Ru-N(2). In contrast, there is no changes in Ru-N(5)O bond. For higher pHs, there is a 3à4 equilibrium (pK a = 11.5) and the conversion of Ru-N(5)O for Ru-N(5) O 2 . The Ru-N(5) of 4 shows a larger ionic character than 3. Thus, Ru-NO in 1-4 has worthy stability about a large pH range, showing potential application as NO scavengers. K E Y W O R D S bond theory, computational chemistry, interacting quantum atoms, nitric oxide donor or scavenger compounds, pH influence

The nature of the NO bond in amine oxides

“…Orenha and Galembeck explained that the behavior of a Ru-N bond is due to the absence of V(Ru,N) between C(Ru) and C(N), and the T A B L E 4 ELF basin components: ELF domain volume, V(Ω i ); domain population, N(Ω i ) domain population contribution from atoms A and B; domain population contribution from atoms A and B in percentage (A% and B%); and population variance, σ 2 (Ω i ). observation of a V(N), was attributed to the dative character of these bonds, as observed in other systems that present dative bonds with strong ionic character [45,68,69].…”

“…The same behavior has been observed in coordinating bonds between metals and ligands. Orenha and Galembeck explained that the behavior of a Ru‐N bond is due to the absence of V(Ru,N) between C(Ru) and C(N), and the observation of a V(N), was attributed to the dative character of these bonds, as observed in other systems that present dative bonds with strong ionic character [45, 68, 69].…”