Molecular stereochemistry of a six-coordinate nickel(II) porphyrin

Kirner, J. F.; Garofalo, John P.; Scheidt, W. Robert

doi:10.1016/0020-1650(75)80004-3

Cited by 43 publications

(48 citation statements)

References 13 publications

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“…Similar behavior was reported for the ligation of piperidine to NiTPP [65] and other Ni(II) porphyrins [64]. In the solid-state, the Ni(II) porphyrins are known to exhibit six coordinate geometry [96][97][98][99][100][101][102].…”

Section: Ni(ii) Perhaloporphyrinssupporting

confidence: 69%

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Sankar

Arunkumar

Bhyrappa

2004

J. Porphyrins Phthalocyanines

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Electronic absorption spectra of divalent metal (Ni(II) and Cu(II)) complexes of 2, 3,7,8,12,13,17,10,15, X = Br, Cl) were examined in various solvents. M(II) perhaloporphyrins exhibited dramatic shifts in their optical absorption spectral features relative to the corresponding metallotetraphenylporphyrins, MTPPs. Copper(II) perhaloporphyrins show significant red-shifts of the absorption bands in coordinating solvents relative to that observed for nickel(II) perhaloporphyrins. The large redshift of the electronic absorption bands and the gain in intensity of the longest wavelength band (Q(0,0)), of Cu(II) perhaloporphyrins in certain coordinating solvents is comparable to that found in meso-tetraphenylporphinatozinc(II), ZnTPP. The solvent dependent spectral features of M(II) perhaloporphyrins are attributed to a coordinative interaction of the solvent with the core metal ion induced by the electron deficient porphyrin macrocycle.

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Section: Ni(ii) Perhaloporphyrinssupporting

confidence: 69%

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Sankar

Arunkumar

Bhyrappa

2004

J. Porphyrins Phthalocyanines

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“…In addition, the core expands by an additional 0.02 Â upon binding two ligands as indicated by the further decrease in (Figure 6). The total expansion of 0.08 Â agrees with the value determined from the 4-and 6-coordinate Ni-porphyrin crystal structures (38,39).…”

Section: Axial Coordination In Nickel Porphyrinssupporting

confidence: 80%

Axial Coordination in Nickel and Vanadium Porphyrins: Transient and Difference Raman Spectroscopy

Shelnutt

Alston

Findsen

et al. 1987

ACS Symposium Series

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Nickel-and vanadium-porphyrin complexes and Ni(II)-reconstituted hemoglobin ( Ni Hb) and myoglobin ( Ni Mb) have been investigated using cw and transient resonance Raman spectroscopy.The state of axial coordination at the metal in these materials can be determined using the characteristic frequencies of the Raman marker lines arising from the porphyrin moiety.The state of axial ligation is highly sensitive to the molecular environment of these geoporphyrin analogs.Whether vanadium porphyrins are 5-or 6-coordinate depends on solvent and π-π aggregation and complexation. Similarly, nickel porphyrins exhibit 4-, 5-, or 6-coordination depending on the molecular environment.Nickel -reconstituted proteins provide well characterized models of hydrophobic cavities such as might exist in a heterogeneous petroleum environment.In the protein cavity a novel 5-coordinate Ni-porphyrin complex is observed. The existence of only one axial ligand is supported by identification of the axial ligand-Ni stretching vibration by isotopic substitution.The frequency of the Ni-ligand mode is consistent with histidine as the fifth ligand. The effects of the T->R change in quaternary structure of the protein environment of the Ni porphyrin are also observed in the Raman spectrum. The photoinitiated ligand-release and ligand-uptake processes in excited states of the Ni porphyrins and Ni-reconstituted proteins were also investigated. Laser excitation (~10-ns duration) of the complexes formed in coordinating solvents induces the release of axial ligands, but does not induce release of the histidine ligand of Ni-reconstituted hemoglobin and myoglobin. The results indicate that the protein matrix controls ligation dynamics by promoting rapid geminate recombination of the ligand.

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“…7b wiedergegeben, welche ein Histogramm aller in Nickel(I1)-Povphyrinaten gefundenen (gemittelten) (Ni-N)-Abstlnde zeigt16). Die Trennung zwischen den 'low-spin'-Komplexen und dem einzigen bekannten 'high-spin'-Komplex [22] ist nun wesentlich weniger ausgepragt, was offenbar das Resultat der einander entgegengesetzten Bestrebungen nach minimaler Ringspannung und optimaler Ni-Koordination ist. Beim analogen Histogramm der Kristallstrukturen von Ni(1I)-Komplexen mit hydroporphinoiden LigandenI7) (Fig.…”

Section: Schematiskrte Darstellungen Der Konformationellen Kopplungunclassified

Die Sattelkonformation der hydroporphinoiden Nickel(II)‐Komplexe: Struktur, Ursprung und stereochemische Konsequenzen

Kratky¹,

Waditschatka²,

Angst³

et al. 1985

Helvetica Chimica Acta

136

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Thirteen crystal structures document the general phenomenon of coordination-hole contraction in hexahydro-and tetrahydroporphinoid ligands of complexes with small metal ions such as low-spin Ni(I1). The contraction is characterized by a deformation of the ligand system towards a saddle-shaped, ruMed conformation of approximate S, symmetry. The central metal ion is coplanar with the four coordinating N-centers whereas the four C(meso)-atoms arc situated alternately above and below this coordination plane. Increasing steepness of the saddle (parameter d,) is associated with decreasing metal-N distances. For metal pyrrocorphinates, d, increases in the order Cu(11) < (pyridine) Co(l1) < Ni(II), for Ni(1l) complexes it does so in the order porphyrin < chlorin ' ) ')Beziehbar von der Hauptbibliothek der ETH Zurich. Alle in dieser Arbeit vorkommenden chiralen Verbindungen waren in racemischer Form.

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Molecular stereochemistry of a six-coordinate nickel(II) porphyrin

Cited by 43 publications

References 13 publications

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins

Axial Coordination in Nickel and Vanadium Porphyrins: Transient and Difference Raman Spectroscopy

Die Sattelkonformation der hydroporphinoiden Nickel(II)‐Komplexe: Struktur, Ursprung und stereochemische Konsequenzen

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