Reactivity of [1,4,7,10,13-pentaazacyclohexadecane-14,16-dionato(2-)]nickel(II) toward derivatives of methyl-coenzyme M

Drain, Charles Michael; Sable, David B.; Corden, Barry B.

doi:10.1021/ic00332a029

Cited by 16 publications

(19 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The final step in methane formation by methanogenic bacteria requires an unusual, highly reduced nickel tetrapyrrole cofactor, F 430 , to catalyze the reduction of a methyl sulfide to methane and a disulfide . The severe distortion of F 430 in the enzyme modulates the reactivity since planar nickel porphyrins, such as nickel protoporphyrin IX, are ineffective by themselves or in the enzymatic system, while a non-porphyrin, nonplanar nickel macrocycle also catalyzes the methyl sulfide reduction ranging from photosynthetic reaction centers 3c to vitamin B 12 3b.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Photophysical Properties of Conformationally Distorted Nickel Porphyrins. 1. Nickel(II) Dodecaphenylporphyrin

et al. 1996

View full text Add to dashboard Cite

Transient absorption measurements with subpicosecond resolution have been performed on nickel(II) dodecaphenylporphyrin (NiDPP), a highly nonplanar tetrapyrrole. Following photoexcitation, NiDPP deactivates by the pathway (π,π*) f (d,d) f ground state, the route proposed previously for planar analogues. However, the (π,π*) state has now been spectrally and kinetically resolved, and evidence is presented that the deactivation proceeds mainly in the singlet manifold. The lifetime of the 1 (π,π*) state of NiDPP is about 0.7 ps in all solvents investigated and increases only slightly as the temperature is reduced. The (d,d) state exhibits complex spectral evolution over the following 20 ps or more, which is interpreted in terms of vibrational relaxation and cooling, together with changes in the conformation of the porphyrin macrocycle. The ligandfield excited state decays with a lifetime of about 120 ps in toluene, but this decay time, like the vibrational and conformational dynamics in the (d,d) state, slows considerably in mineral oil and at low temperature. The solvent dependence of the ground-state absorption spectrum combined with the dependence of the excitedstate kinetics on detection wavelength, viscosity, and temperature suggests that NiDPP has a number of accessible conformers and that the energies of these conformers and the barriers between them differ with the electronic state. Such conformers probably differ in the type and degree of nonplanar distortion (e.g., saddle or ruffled) and in the orientations and solvent interactions of the phenyl rings. The results presented here for NiDPP, together with previous time-resolved data on metal-free nonplanar porphyrins, suggest that key properties of nonplanar tetrapyrroles include ready access to multiple conformers and a propensity for photoinduced conformational changes. Collectively, the results of spectroscopic studies on nonplanar porphyrins suggest that static and dynamic functional properties of tetrapyrrole cofactors in vivo may be strongly modulated by the steric constraints imposed by a protein matrix.

show abstract

Section: Introductionmentioning

confidence: 99%

Dynamic Photophysical Properties of Conformationally Distorted Nickel Porphyrins. 1. Nickel(II) Dodecaphenylporphyrin

et al. 1996

View full text Add to dashboard Cite

show abstract

“…Porphyrin π cation radicals incorporating high oxidation states of Fe, Mn, Cr, and Ru catalyze epoxidations, hydroxylations, and oxidations of alkenes, alkanes, and other organic substrates and Ni(III) tetrapyrroles (factor 430) have been invoked in the catalytic cycle of methanogenic bacteria . Porphyrins with elegantly designed superstructures have also been synthesized in attempts to construct regiospecific catalysts that mimic the many biological processes mediated by porphyrins…”

mentioning

confidence: 99%

Ligand-Bridged Heterobimetallic Polymers: Silver(I)−Benzothiadiazole−Nickel Porphyrin Cation−Benzothiadiazole Arrays

et al. 1996

View full text Add to dashboard Cite

Stable crystals of (NiOETPP(BTD)2 +)(Ag+)(ClO4)2·2CH2Cl2 were obtained from the oxidation of NiOETPP with AgClO4 in CH2Cl2 followed by addition of BTD. (OETPP = 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin; BTD = 2,1,3-benzothiadiazole). An X-ray structure reveals that the complex is a bimetallic polymeric aggregate composed of [−Ag+−BTD−NiP+−BTD−] subunits in which the BTDs act as bidentate ligands that bind to the Ni and Ag ions via their their two nitrogens. As in the parent NiOETPP, the ligated oxidized porphyrin adopts a severely distorted saddle conformation. The saddle distortion and peripheral substituents form superstructural trenches that control the orientations of the two BTD axial ligands which are forced into a nearly orthogonal configuration along the axes defined by opposite porphyrin nitrogens.

show abstract

“…Additionally, some derivates of these complexes have been shown to interact with and activate dioxygen [7][8][9]. The question whether the Ni-dione complex in its neutral or dicationic form is able to generate methane from the cofactor methyl coenzyme-M, has been contradictorily discussed in the literature [10,11]. Rokita and co-workers synthesised the small azamacrocyclic Ni(II) complex (NiHFGN, Fig.…”

Section: = F)mentioning

confidence: 99%

Nickel and cobalt complexes of 15,15-disubstituted 1,4,7,10,13-pentaazacyclohexadecane-14,16-dione ligands

Pieve

Spingler

2012

Inorganica Chimica Acta

View full text Add to dashboard Cite

Nickel and cobalt complexes of 15,15-disubstituted 1,4,7,10,13-pentaazacyclohexadecane-14,16-dione ligands Da Pieve, Chiara; Spingler, Bernhard Abstract: The synthesis of the novel Co(III) (15,15-difluoro-1,4,7,10,13-pentaazacyclohexadecane-14,16-dione) acetate complex from different cobalt sources is described. Furthermore, the corresponding nickel complex and its new analog with the 15-fluoro-15-methyl-1,4,7,10,13-pentaazacyclohexadecane-14,16-dione ligand were studied in great detail including cyclic voltammetry and single crystal analyses of a total of 6 complexes. The results for the nickel compounds showed that depending upon ligand substitution and solvent, an N3 or, after a double deprotonation, an N5 coordination mode could be observed and characterized in the solid state and in solution. Moreover, cyclic voltammetric analyses were performed revealing that the Ni(II/III) oxidation potentials are becoming more positive with the increasing number of fluorine atoms. This effect is due to the electron withdrawing property of fluorine that is reducing the electron richness of the metal ion. (C) -15-methyl-1,4,7,10,13-pentaazacyclohexadecane-14,16-dione ligand were studied in great detail including cyclic voltammetry and single crystal analysis of a total of 6 complexes. The results for the nickel compounds showed that depending upon ligand substitution and solvent, an N3 or, after a double deprotonation, an N5 coordination mode could be observed and characterized in the solid state and in solution. Moreover, cyclic voltammetric analyses were performed revealing that the Ni(II/III) oxidation potentials are becoming more positive with the increasing number of fluorine atoms. This effect is due to the electron withdrawing property of fluorine that is reducing the electron richness of the metal ion.

show abstract

Reactivity of [1,4,7,10,13-pentaazacyclohexadecane-14,16-dionato(2-)]nickel(II) toward derivatives of methyl-coenzyme M

Cited by 16 publications

References 0 publications

Dynamic Photophysical Properties of Conformationally Distorted Nickel Porphyrins. 1. Nickel(II) Dodecaphenylporphyrin

Dynamic Photophysical Properties of Conformationally Distorted Nickel Porphyrins. 1. Nickel(II) Dodecaphenylporphyrin

Ligand-Bridged Heterobimetallic Polymers: Silver(I)−Benzothiadiazole−Nickel Porphyrin Cation−Benzothiadiazole Arrays

Nickel and cobalt complexes of 15,15-disubstituted 1,4,7,10,13-pentaazacyclohexadecane-14,16-dione ligands

Contact Info

Product

Resources

About