Metal complexes of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, N-tetramethylcyclam

Barefield, E. Kent; Wagner, Frank S.

doi:10.1021/ic50128a042

Cited by 190 publications

(78 citation statements)

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“…These complexes are generally less stable than complexes of its unsubstituted analogue, cyclam (8). [36] In the present case, the zinc() ion is removed from the macrocycle by formation of the more stable bis(thiolate) of zinc, releasing the free ligand.…”

Section: Complexation Experimentsmentioning

confidence: 79%

Zinc Thiolate Complexes [ZnL_n(SR)]⁺ with Azamacrocyclic Ligands: Synthesis and Structural Properties

Notni¹,

Görls²,

Anders³

2006

Eur J Inorg Chem

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A series of 24 novel zinc thiolate complexes containing saturated macrocyclic polyamine ligands with the general formula [Zn(L n )(SR)]ClO 4 (L n : n-dentate azamacrocyclic ligand) has been synthesized. Two different thiolate ligands (R = phenyl, benzyl) and 12 macrocyclic ligands with ring sizes varying from 11 to 16 atoms and containing three, four, and five nitrogen donors (including a new macrocyclic triamine ligand, 8-methyl-[11]aneN 3 ) have been used. The solid-state structures of 20 of the 24 complexes have been characterized by X-ray diffraction. The crystal lattice of all compounds is comprised exclusively of monomers. The tetracoordinate N 3 S compounds exhibit Zn-S bond lengths ranging from

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Section: Complexation Experimentsmentioning

confidence: 79%

Zinc Thiolate Complexes [ZnL_n(SR)]⁺ with Azamacrocyclic Ligands: Synthesis and Structural Properties

Notni¹,

Görls²,

Anders³

2006

Eur J Inorg Chem

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“…2.03 Å and 2.15 Å. It has been pointed out a while ago by Barefield and Wagner [6] that macrocycles with tertiary amines such as tetramethylcyclam could accommodate a sixth ligand at short distance with a significant fold-ing of the macrocycle resulting in two pairs of nonequal Cu-N bonds. Such an interpretation could perhaps be consistent with the FT difference spectra of Figure 5(B).…”

Section: Inactive Xerogels Complexed With Cuclmentioning

confidence: 98%

“…Starting from the consideration that saturated polyazamacrocycles, especially the 1,4,8,11-tetraazacyclotetradecane (cyclam), had a strong capability to bind transition metal cations, [6][7][8][9][10] two partner groups (located in Dijon and Montpellier) settled upon incorporating cyclam units within silica matrices prepared by a sol-gel process. [11][12][13] Two strategies illustrated in Scheme 1 were explored: [13] (A) The hydrolysis and polycondensation of [Cu-(cyclam)] 2+ or [Co(cyclam)] 2+ alkoxysilylated complexes quantitatively produced hybrid polymers incorporating the metallated cyclam units.…”

Section: Introductionmentioning

confidence: 99%

A Study Using X‐ray Absorption and Emission Spectroscopy of Dioxygen‐Binding Xerogels Incorporating Cyclam Units Complexed with Copper Salts

et al. 2005

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X‐ray absorption spectroscopy was used to elucidate how hybrid xerogels complexed with CuCl2 could reversibly bind molecular dioxygen. Difference EXAFS analyses at the Cu K‐edge suggest that dioxygen could bridge two Cu atoms in a μ‐η1:η1 peroxo‐like conformation with unequal Cu···O distances. Only the short distance (RCu–O1 = 1.86 ± 0.01 Å) was unambiguously determined and looks typical of a CuII site. The Cu···Cu internuclear distances would be rather long: RCu–Cu ≈ 4.0 Å (3.9 Å) for the oxygenated (oxygen‐free) xerogels. Cl K‐edge EXAFS spectra revealed the pre‐existence in the oxygen‐free xerogels of CuI sites with short Cl–Cu bonds (2.11 ± 0.03 Å). Pentacoordinate CuII sites with a longer Cl–Cu bond (2.45 ± 0.03 Å) were also identified. Another signal at a further distance (2.73 ± 0.03 Å) suggests that the Cl ions could bridge mixed‐valence {CuI,CuII} sites. In oxygenated xerogels complexed with CuCl2, ca. 75 % of the Cu atoms would be singly bound to dioxygen while the signature of the pentacoordinate CuII sites would totally vanish. Substituting CuBr2 for CuCl2 yields xerogels with a poor capability to bind dioxygen. This is remarkably correlatedwith a decrease of the signatures at RCu–O1 = 1.86 Å and RCu–Cu 4.0 Å. EXAFS spectra of the oxygen‐free xerogel complexed with CuBr2 again exhibit signatures assigned to short (2.30 Å)/long (2.49 Å) Cu–Br bonds as expected for mixed‐valence {CuI,CuII} systems. Inactive xerogels prepared with metallated cyclams seem to undergo a structural change during hydrolysis and polycondensation. Deconvoluted XANES spectra of the active xerogels exhibit a strong pre‐edge resonance which is characteristic of mixed‐valence CuI sites. This interpretation was supported by ab initio XANES simulations carried out beyond the muffin‐tin approximation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…1) were prepared, and investigated as homogeneous electrocatalysts for CO 2 reduction. With an aim to address the demetalation issue of Cu(II)-cyclam, N-alkylation with a cross-bridging propylene group in Cu(II)-PCB-cyclam was adopted with the following two rationales: (1) [16]. To a solution of cyclam (0.075 mmol) in EtOH (10 mL), Ni(ClO 4 ) 2 ·6H 2 O (1.87 mmol dissolved in EtOH (10 mL)), was added dropwise.…”

Section: Introductionmentioning

confidence: 99%

Electrocatalytic Reduction of CO₂by Copper (II) Cyclam Derivatives

Kang

Dale

Sarkar

et al. 2015

Journal of Electrochemical Science and Technology

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This study investigates Cu(II) complexes of cyclam, propylene cross-bridged cyclam (PCB-cyclam), and propylene crossbridged cyclam diacetate (PCB-TE2A) as homogeneous electrocatalysts for CO 2 reduction in comparison with Ni(II)-cyclam. It is found that Cu(II)-cyclam can catalyze CO 2 reduction at the potential close to its thermodynamic value (0.75 V vs. Ag/AgCl) in tris-HCl buffer (pH 8.45) on a glassy carbon electrode. Cu(II)-cyclam, however, suffers from severe demetalation due to the insufficient stability of Cu(I)-cyclam. Cu(II)-PCB-cyclam and Cu(II)-PCB-TE2A are revealed to exhibit much less demetalation behavior, but poor CO 2 reduction activities as well. The inferior electrocatalytic ability of Cu(II)-PCB-cyclam is ascribed to its redox potential that is too high for CO 2 reduction, and that of Cu(II)-PCB-TE2A to the steric hindrance preventing facile contact with CO 2 molecules. This study suggests that in addition to the redox potential and chemical stability, the stereochemical aspect has to be considered in designing efficient electrocatalysts for CO 2 reduction.

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Metal complexes of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, N-tetramethylcyclam

Cited by 190 publications

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Zinc Thiolate Complexes [ZnL_n(SR)]⁺ with Azamacrocyclic Ligands: Synthesis and Structural Properties

Zinc Thiolate Complexes [ZnL_n(SR)]⁺ with Azamacrocyclic Ligands: Synthesis and Structural Properties

A Study Using X‐ray Absorption and Emission Spectroscopy of Dioxygen‐Binding Xerogels Incorporating Cyclam Units Complexed with Copper Salts

Electrocatalytic Reduction of CO₂by Copper (II) Cyclam Derivatives

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Metal complexes of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, N-tetramethylcyclam

Cited by 190 publications

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Zinc Thiolate Complexes [ZnLn(SR)]+ with Azamacrocyclic Ligands: Synthesis and Structural Properties

Zinc Thiolate Complexes [ZnLn(SR)]+ with Azamacrocyclic Ligands: Synthesis and Structural Properties

A Study Using X‐ray Absorption and Emission Spectroscopy of Dioxygen‐Binding Xerogels Incorporating Cyclam Units Complexed with Copper Salts

Electrocatalytic Reduction of CO2by Copper (II) Cyclam Derivatives

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Zinc Thiolate Complexes [ZnL_n(SR)]⁺ with Azamacrocyclic Ligands: Synthesis and Structural Properties

Zinc Thiolate Complexes [ZnL_n(SR)]⁺ with Azamacrocyclic Ligands: Synthesis and Structural Properties

Electrocatalytic Reduction of CO₂by Copper (II) Cyclam Derivatives