Title

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 5. Structural Investigation of Nickel(II) Bacteriopetroporphyrins Related to the Bacteriochlorophylls c and d: Evidence for Localized Conformational Distortion in the c-Series

Document Type

Article

Publication Date

1-1-1993

Abstract

The structural investigation of three bacteriopetroporphyrins related to bacteriochlorophylls c and d reveals a localized distortion of the porphyrin macrocycle in the c-series at the meso-substituted C(20) position. This presents a structural rationale for the differences observed in reactivity and absorption spectra between bacteriochlorophylls bearing a C(20) methyl group and those without. The crystal structures determined for the Ni(II) bacteriopetroporphyrins present the first such analysis for geoporphyrins derived from bacteriochlorophylls of the green sulfur bacteria. Crystal data 1; C38H44N4NiO2, Mr = 647.5, triclinic, P1̄, a = 10.449(3) Å, b = 12.469(4) Å, c = 14.622(8) Å, α = 64.93(3)∘, β = 72.37(4)∘, γ = 68.50(3)∘, V= 1580.7(11) Å3, Z = 2, DX = 1.360 Mg·m−3, λ(Mo Kα) = 0.710 69 Å, μ = 0.654 mm−1, F(000) = 688, 130 K, R = 0.056 for 4566 reflections with I > 3σ(I); 2, C37H42N4NiO2, Mr = 633.5, triclinic, P1̄, a = 9.581(3) Å, b = 12.365(5) Å, c = 14.429(7) Å, α = 110.03(3)∘, β = 95.82(3)∘, γ = 101.34(3)∘, V= 1548.0(11) Å3, Z = 2, Dx = 1.359 Mg·m−3, λ(Mo Kα) = 0.710 69 Å, μ = 0.667 mm−1, F(000) = 672, 130 K, R = 0.042 for 5452 reflections with I > 3σ(I); 3; C36H40NiO2, Mr = 619.4, triclinic, P1̄, a = 8.248(4) Å, b = 11.487(7) Å, c = 16.164(8) Å, α = 93.28(5)∘, β = 91.11(4)∘, γ= 100.42(4)∘, V = 1503.1(13) Å3, Z = 2, DX = 1.369 Mg·m−3, λ(Mo Kα) = 0.710 69 Å, μ = 0.686 mm−1, F(000) = 656, 130 K, R = 0.059 for 5269 reflections with I > 2σ(I). © 1993, American Chemical Society. All rights reserved.

Publication Source (Journal or Book title)

Inorganic Chemistry

First Page

1259

Last Page

1265

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