Interconversion between Polymeric Orange and Monomeric Green Forms of a Schiff Base-Oxovanadium(IV) Complex

Kiyohiko Nakajima, Masaaki Kojima, Shunryo Azuma, Ryuichi Kasahara, Masanobu Tsuchimoto, Yoshihiro Kubozono, Hironobu Maeda, Setsuo Kashino, Shigeru Ohba, Yuzo Yoshikawa, Junnosuke Fujita

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    Abstract

    The orange and green forms of the Schiff base-oxovanadium(IV) complex, [VO{sal-(RR)-stien}]·MeOH (1, green), [VO{sal-(RR)-stien}]·2CHC13 (2, green), and [VO{sal-(RR)-stien}]·CH3CN (3, orange) (H2{sal-(RR)-stien} = N,N′-disalicylidene-(RR)-1,2-diphenyl-1,2-ethanediamine), have been prepared, and their crystal structures were determined by an X-ray method. The green forms, 1 and 2, contain mononuclear square pyramidal molecules of the complex, while the orange form 3 consists of individual complexes stacked to give an infinite linear ⋯V=O⋯V=O⋯ chain. 1, which crystallizes as monoclinic in space group P21 with Z=4, has the cell parameters a=16.684(2), b=16.923(4), c=9.249(3) Å, β = 105.76(2)°, and V=2513(1) Å3. 2, which crystallizes as triclinic in space group P1 with Z=2, has the cell parameters a = 13.187(3), b = 13.469(3), c = 10.450(3) Å, α = 103.72(2), β = 103.20(3), γ = 63.03(2)°, and V = 1591.2(7) Å3. 3 crystallizes as triclinic in space group P1 with Z=2. The cell parameters are a = 13.300(3), b = 13.667(4), c = 7.551(1) Å, α = 90.44(2), β = 94.51(2), γ = 97.36(2)°, and V = 1357(1) Å3. The final R indices are R = 0.059 and RW = 0.062 for 1, R = 0.098 and RW = 0.090 for 2, and R = 0.053 and Rw = 0.042 for 3. The structural characteristics of these complexes are compared and discussed. 3 shows piezochromism (mechanochromism); its color changes from orange to green upon grinding. 1 and 2 turn orange when heated at 120 °C for a few minutes. The extent of conversion either by grinding or heating was studied by EXAFS (X-ray absorption fine structure) and IR spectroscopy. The orange crystals turn green when exposed to chloroform vapor, and the green crystals turn orange upon exposure to acetonitrile vapor.

    Original languageEnglish
    Pages (from-to)3207-3216
    Number of pages10
    JournalBulletin of the Chemical Society of Japan
    Volume69
    Issue number11
    DOIs
    Publication statusPublished - Nov 1996

    ASJC Scopus subject areas

    • Chemistry(all)

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