Macrocyclic Hydroperoxocobalt(III) Complex:  Photochemistry, Spectroscopy, and Crystal Structure

Abstract

The hydroperoxocobalt complex [L(2)(CH(3)CN)CoOOH](ClO(4))(2).CH(3)CN (L(2) = meso-5,7,7,12,14,14-Me(6)-[14]aneN(4)) crystallizes with discrete anions, cations, and solvate acetonitrile molecules in the lattice. The complex crystallizes in the monoclinic space group P2(1)/n, a = 10.4230(5) A, b = 16.1561(8) A, c = 17.4676(9) A, beta = 92.267(1) degrees, V = 2939.2(3) A(3), Z = 4. The O-O bond length is 1.397(4) A, and the O(2)-O(1)-Co angle spans 117.7 degrees. The O-O stretch in the infrared spectrum appears at 815 cm(-1). The 355- and 266-nm photolysis of acidic aqueous solutions of L(2)(H(2)O)CoOOH(2+) results in homolytic splitting of the Co-O bond and yields L(2)Co(H(2)O)(2)(2+) and HO(2)(*)/O(2)(*-) as the only products. The two fragments were scavenged selectively in separate experiments with O(2) and C(NO(2))(4). There is no evidence for photochemical O-O bond homolysis, presumably because the appropriate optical transition is masked by the HO(2)-to-Co LMCT transition.

Transformation of Nitrile to Cyanide and Aldehyde Using a Cobalt(II) Complex and Dioxygen

“…[13] So far, we do not have proof of the occurrence of a hydroperoxo complex [Co III (salmdpt)OOH] (4) as an intermediate, but such compounds are known, and the first full characterization of such a species with a macrocyclic ligand has been reported by Guzei and Bakac. [14] Furthermore, Karlin and co-workers observed a dinuclear copper hydroperoxo complex (characterized by UV/Vis and resonance Raman spectroscopy). [6] The presence of dioxygen and water is necessary, because under inert conditions 1 could be recrystallized from acetonitrile solutions.…”

Hydrogenation of a Rhodium Peroxido Complex by Formate Derivatives: Mechanistic Studies and the Catalytic Formation of H2O2 from O2

“…[10,13,16] The 19 F NMR spectrum of 6 a displays four signals for the tetrafluoropyridyl ligand, which indicates a hindered rotation about the rhodium-carbon bond. [10,13,16] A broad signal in the 1 H NMR spectrum at d = 8.38 ppm can be attributed to the hydroperoxido ligand, [10,12,17] and a resonance at d = 8.15 ppm is assigned to the formato ligand. [18] The latter signal correlates with a signal for the {OC(O)H} ligand at d = 167.5 ppm in the 13 C domain of a 1 H, 13 C-HMQC NMR spectrum.…”

“…The IR spectrum of 7 a shows an absorption band at 969 cm À1 for the Rh{k 2 -OOC(O)O} moiety. [20b] This band shifts to 959 cm À1 for the 17 O-labeled isotopologue 7 c (Dñ = 10 cm À1 ) and to 948 cm À1 for the 18 O-labeled isotopologue 7 b (Dñ = 21 cm À1 ), respectively ( Table 1).…”

Umwandlung eines Nitrils in Cyanid und Aldehyd unter Verwendung von Sauerstoff und einem Cobalt(II)‐Komplex

“…Die erste vollständige Charakterisierung eines solchen Komplexes mit einem makrocyclischen Liganden stammt von Bakac und Guzei. [14] Auch Karlin et al beobachteten einen zweikernigen Kupfer-Hydroperoxo-Komplex (der mithilfe von UV/Visund Resonaz-Raman-Spektroskopie charakterisiert wurde). [6] Bei [15] Bisher …”