Hydrolysis and Photolysis of Tris(tetraethylammonium) Pentacyanoperoxynitritocobaltate(III): Evidence for a Novel Complex, Pentacyanonitratocobaltate(III)

Abstract

Dedicated to the memory of Prof. Luigi M. Venanzi, a friend and colleague At pH 2, the rate constant of hydrolysis of tris(tetraethylammonium) pentacyanoperoxynitritocobaltate(III) in H 2 O is 9.6 Â 10 À6 s À1 . In the absence of any light, ONOO À is not replaced by H 2 O and isomerizes within the coordination sphere to NO 3 À . The novel complex [Co(CN) 5 NO 3 ] 3À released NO 3 À slowly, as detected by ion chromatography. At pH 6, no hydrolysis is observed. Direct photolysis, both at pH 2 and pH 6, of tris(tetraethylammonium) pentacyanoperoxynitritocobaltate(III) by irradiation (YAG laser) at 355 nm destroys the coordinated ONOO À and releases NO 2 . , which hydrolyzes to NO 3 À and NO 2 À . We also measured the 59 Co-NMR spectra of [Co(CN) 5 OONO] 3À and [Co(CN) 5 H 2 O] 2À ; the chemical shifts correspond very well to those predicted and are in agreement with the expected contribution to the ligand field by H 2 O and ONOO À .

Mechanistic Studies on the Reaction of Nitroxylcobalamin with Dioxygen: Evidence for Formation of a Peroxynitritocob(III)alamin Intermediate

“…30,31 If the reaction proceeds via this type of reaction pathway, the NO 2 Cbl:(H 2 OCbl + + HOCbl) product ratio will be dependent on the total cobalamin concentration, 31 with more NO 2 Cbl expected at higher cobalamin concentrations. However, HPLC experiments showed that the NO 2 Cbl:H 2 OCbl + product ratio is the same 61 Additionally Richter-Addo et al 60 found that the rate of the reaction of the picket fence porphyrin complex [Fe(tpivpp)(NO)] with air in CHCl 3 solution is enhanced by light. A control experiment in the absence of regular laboratory light showed that light has no effect on the observed product ratio for our system, Supporting Information, Figure S17.…”

The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity

“…The Cu­(II)–peroxynitrite complex then undergoes thermal transformation to a Cu­(II)–nitrite complex . Other non-porphyrin peroxynitrito metal complexes have been investigated by Koppenol and coworkers, including pentacyano­peroxynitrito­cobaltate­(III). , …”

Dinitrosyliron Complex [(PMDTA)Fe(NO)2]: Intermediate for Nitric Oxide Monooxygenation Activity in Nonheme Iron Complex

“…[M–O 2 – ]/[M–O 2 2– ]/[M–OOH – ] (M = Cr, Fe, Co, Cu) complexes promoted dioxygenation of NO (or NO + ) into NO 3 – via the formation of [M­(κ 1 - O -OONO)] intermediates, which features ν ON(OO) stretching frequencies at 1621 and 1598 cm –1 in complexes [Co­(CN) 5 (κ 1 - O -OONO)] 3– and [Tp tBu,Me Co­(κ 1 - O -OONO)], respectively (Table ). ,,− Unlike the rearrangement of [Cr III (12-TMC)­(κ 1 - O -OONO)­(Cl)] into the respective [Cr III (NO 3 – )] adduct, homolytic cleavage of the O–O bond within [Cr III (14-TMC)­(κ 1 - O -OONO)­(Cl)] results in the formation of released • NO 2 and Cr IV -oxo intermediate, which reacts with additional NO to afford a Cr III -NO 2 – adduct. , On the other hand, two-electron-reduction power of the Mn III center in [(TAML)­Mn III (κ 1 - O -OONO)] promotes the formation of [(TAML)­Mn V (O)] and released NO 2 – . In comparison with [M­(κ 1 - O -OONO)] intermediates, complex [(TMG 3 tren)­Cu­(κ 2 - O , O ′-OONO)] derived from the reaction of Cu–O 2 – precursor and NO transforms into [Cu-NO 2 – ] adduct and released O 2 . , …”