Title

STRUCTURE and CONFORMATION OF PHOTOSYNTHETIC PIGMENTS and RELATED COMPOUNDS. 2. NICKEL (II) METHYL PYROPHEOPHORBIDE a–A SEVERELY ISTORTED CHLOROPHYLL DERIVATIVE

Document Type

Article

Publication Date

1-1-1991

Abstract

The crystal structure of Ni(II) methyl pryopheophorbide a (3) (CMH34N4Ni03, Mu= 605.4) was determined by x‐ray diffraction methods in order to determine the influence of the nickel‐ion on the ring conformation. The crystals were blue octahedrons and crystallized in the tetragonal space group P4121,2 with a= 14.727(4) Å, c = 26.666(12) Å, V= 5781(3) Å3Z= 8, D= 1.391 mg/m3. (Mo Kα) = 0.71069 Åμ= 0.713 mm−1, F(000) = 2544, 130 K. The final R value was 0.064 for 4096 observed reflections, wR = 0.065. The molecule is severely distorted and shows a saddle‐shaped ring conformation, the β‐pyrrole atoms being displaced up to 0.6 A out of the plane of the nitrogens. The severe deformation restricts the use of Ni‐derivatives in spectroscopic model studies on chlorophylls and provides an example for the conformational flexibility of the phorbin macrocycle. Copyright © 1991, Wiley Blackwell. All rights reserved

Publication Source (Journal or Book title)

Photochemistry and Photobiology

First Page

841

Last Page

846

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