Spectral-structural correlations in high-spin cobalt(II) complexes

Banci, Lucia; Bencini, Alessandro; Benelli, C.; Gatteschi, Dante; Zanchini, C.

doi:10.1007/bfb0111296

Cited by 259 publications

(211 citation statements)

References 190 publications

Supporting

Mentioning

184

Contrasting

Order By: Relevance

“…This absorption band consists of three components whose overall width is analogous to that reported for the corresponding absorption in the tetrahedral [COX,]*-, suggesting little evidence of any C,, perturbation [26,27]. This is in agreement with solution magnetic susceptibility measurements which gave a value of 4.27 BM, within the range typically observed for tetrahedral Co2 + complexes (3.98-4.82 BM) [28,29].…”

Section: Solution and Solid-state Structure Of Co(n-meim)(ci)2 (1)supporting

confidence: 82%

“…2) shows Co2+ to be tetrahedrally coordinated; the bond lengths and angles in the molecule are normal within the observed standard deviations of the few tetrahedral CoA2X, compounds that have been characterized and are different from the polymeric six-coordinate violet form of CoPy2C1, [24,29]. The somewhat shorter Co-Nl (2.004 A) and Co-N3 (2.007 A) bond lengths of 1 versus those reported for the 4-methylpyridine complex (2.03 and 2.06 A) reflect the greater basicity of the N-MeIm ligand (pK, = 7.06) versus 4-MePy (pK, = 5.25) [30].…”

Section: Solution and Solid-state Structure Of Co(n-meim)(ci)2 (1)mentioning

confidence: 72%

“…While octahedral complexes also show bands in tlhis same region (4T1g (F)-t4T2, (F) (950-1550 nm) and 4T1g(F) -4T1,(P) (450-650 nm), the molar extinction coefficients of the 4T1g (F) -+4T2g (F) transition typically range from 5 to 40 while those of the 4T1,(F) -4TI,(P) transition range from 15 to 60, well below those reported for 2 [29,40]. In comparison, the binuclear Fe"+ compound 5, appears featureless in the visible region owing to a strong tailing absorbance at 312 nm ( E~ = 30000) [9].…”

Section: Physical Characterizationmentioning

confidence: 76%

“…The presence of excited energy levels quite close to the ground state, which is independent of coordination geometry, induces fast relaxation of the three unpaired electrons leading to the type of broad spectra (500-4500 Gauss) shown in Fig. 6 for 2 even at 4 K [29,44]. These data suggest that the two Co2+ centers are not strongly antiferromagnetically coupled.…”

Section: Physical Characterizationmentioning

confidence: 94%

“…Under identical conditions, simple Fez+ and Fe3+ salts in the presence of OIPh were unable to catalyze any of these reactions. 29 The intermolecular kinetic isotope effect for alkane C-H oxidation was determined by the competitive oxidation of cyclohexane and cyclohexane-dlz (k& = 2.?!). 30 This small intermolecular KIE is consistent with some,3i-33 but not all,34 studies for the oxidation of alkanes by MMO and is indicative of only a minor contribution from C-H bond breaking in the rate-determining step of substrate oxidation.…”

Section: N-melmmentioning

confidence: 99%

See 4 more Smart Citations

Binuclear Non-heme Iron Catalysts

Caradonna¹

2004

View full text Add to dashboard Cite

This project involved the investigation of the ability of non-heme iron metalloenzyme reactivity model complexes to catalyze the oxidation of alkane and arene molecules. The objectives were to synthesize a series of non-heme mononuclear and dinuclear iron complexes, characterize their electronic structure and reactivity properties, characterize intermediates formed during oxygen atom transfer chemistry, and elucidate the mechanisms and specificity of the reactions. These data also were to be compared to analogous heme-based chemistry.A series of diferrous, ferrous/ferric, and diferric complexes were synthesized from simple polyamide and polycarboxylate ligands and characterized by visible absorption, EPR and IR spectroscopy and by cyclic voltametry. The diferrous compounds, which are all powerful reductants, heterolytically decompose peracids and are capable of acting as oxygen atom transfer catalysts when reacted with oxygen atom donor compounds and simple olefins, yielding both allylic oxidation and epoxidation products. Lowtemperature optical spectroscopic studies provide evidence in support of an Fe(IV)=O intermediate, rather than an 0-donor adduct, as the reactive species. An isostructural dicobalt(I1) complex gives rise only to epoxidation products. These reactivity studies provide important new information of the chemistry of dinuclear nonheme iron systems.Publications resulting from this project:1. 2.3. 4."Fe2+-catalyzed heterolytic RO-OH bond cleavage and substrate oxidation: A fhctional synthetic non-heme iron monooxygenase system", Foster TL, Caradonna ' in anhydrous 1% methanol-acetonitrile under anaerobic conditions afforded @?e22+(Hzbamb)2(N-MeIm)2] (1)25a (60% yield). Isothermal distillation techniquesls indicate that 1 has a molecular weight of 4 100, consistent with its dimeric formulation. EPR spectra of 1 show a g H % 16 signal, suggesting a ferromagnetically coupled S = 4 core as previously reported for an analogous binuclear system.I9 Cyclic voltammetry experiments show two coupled le-oxidationheduction processes; a scanrate-dependent quasi-reversible process at -310 mV ("E) and an electrochemically reversible couple at -690 mV ("E), giving K , , = 2.7 x loa. Repetitive scans showed no significant decrease in either cathodic or anodic current; ligand centered redox behavior was observed outside this region of interest. The scan-rate dependence of AEp, attributed to kinetic effects, allowed the measurement of an intrinsic rate constant, k = 2 x assuming pseudo-first-order kinetics. This rate constant, thought to reflect a structural change, is independent of [I] interfaced to a "33% series U integrator. Mass spectral analyses were performed on a HP 5971 mass-selective detector attached to a HPS890 Series 2 GC. Authentic samples were used to verify all retention times. Expected reaction products were stable to GC conditions.(21) Studies using Fa12 and FeCla were performed and analyzed by GC and GUMS techniques using identical conditions as reported for 1-3 (Table 1) with catalyst:OIF'h:sub...

show abstract

Section: Solution and Solid-state Structure Of Co(n-meim)(ci)2 (1)supporting

confidence: 82%

Section: Solution and Solid-state Structure Of Co(n-meim)(ci)2 (1)mentioning

confidence: 72%

Section: Physical Characterizationmentioning

confidence: 76%

Section: Physical Characterizationmentioning

confidence: 94%

Section: N-melmmentioning

confidence: 99%

See 3 more Smart Citations

Binuclear Non-heme Iron Catalysts

Caradonna¹

2004

View full text Add to dashboard Cite

show abstract

Dioxatriazamacrocycle-N,N′,N″-triacetic Acids: Synthesis, Protonation Constants, and Metal-Complex Studies. Crystal Structure of Hydrogen [1,4-Dioxa-7,10,13-triazacyclopentadecane-7,10,13-triacetato(4)-κN7,κN11,κN13,κO7]copper(1 -) Hydrate (2 : 1) ([Cu(HL1)]⋅0.5 H2O)

Cabral

Delgado

Duarte³

et al. 2000

HCA

View full text Add to dashboard Cite

Structure and Magnetism of a Polycrystalline Transition Metal Soap − CoII[OOC(CH2)10COO](H2O)2

Rueff

Masciocchi²,

Rabu

et al. 2001

Eur. J. Inorg. Chem.

295

127

View full text Add to dashboard Cite

Diaquacobalt(II) n-dodecane-α,ω-dioate (2) has been synthesized by metathesis of the corresponding potassium soap 1 and has been fully characterized by chemical and spectroscopic analysis. The crystal structure of 2 has been established by X-ray powder diffraction techniques combined with electron diffraction experiments. It crystallizes in a monoclinic cell [P2 1 /a; a = 9.6558(8), b = 7.4793(6), c = 19.8936(2) Å , β = 95.648(9)°, V = 1429.7(3) Å 3 ; Z = 2] and consists of stacked layers of cobalt(II) ions connected by carb-

show abstract

Spectral-structural correlations in high-spin cobalt(II) complexes

Cited by 259 publications

References 190 publications

Binuclear Non-heme Iron Catalysts

Binuclear Non-heme Iron Catalysts

Dioxatriazamacrocycle-N,N′,N″-triacetic Acids: Synthesis, Protonation Constants, and Metal-Complex Studies. Crystal Structure of Hydrogen [1,4-Dioxa-7,10,13-triazacyclopentadecane-7,10,13-triacetato(4)-κN7,κN11,κN13,κO7]copper(1 -) Hydrate (2 : 1) ([Cu(HL1)]⋅0.5 H2O)

Structure and Magnetism of a Polycrystalline Transition Metal Soap − CoII[OOC(CH2)10COO](H2O)2

Contact Info

Product

Resources

About