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STRUCTURE and CONFORMATION OF PHOTOSYNTHETIC PIGMENTS and RELATED COMPOUNDS. 2. NICKEL (II) METHYL PYROPHEOPHORBIDE a–A SEVERELY ISTORTED CHLOROPHYLL DERIVATIVE *
Author(s) -
Senge Mathias O.,
Smith Kevin M.
Publication year - 1991
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1991.tb02099.x
Subject(s) - ring (chemistry) , chemistry , crystallography , crystal structure , molecule , nickel , tetragonal crystal system , stereochemistry , derivative (finance) , organic chemistry , economics , financial economics
The crystal structure of Ni(II) methyl pryopheophorbide a (3) (C M H 34 N 4 Ni0 3 , M u = 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 P4 1 2 1 ,2 with a = 14.727(4) Å, c = 26.666(12) Å, V = 5781(3) Å 3 Z = 8, D = 1.391 mg/m 3 . (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.