Kiyohiko NAKAJIMA,Ý Masaaki KOJIMA,* Shunryo AZUMA,* Ryuichi KASAHARA,** Motonobu TSUCHIMOTO,** Yoshihiro KUBOZONO, Hironobu MAEDA,* Setsuo KASHINO,* Shigeru OHBA,** Yuzo YOSHIKAWA and Junnosuke FUJITA*** (ÝAichi Univ. Educ., *Okayama Univ., **Keio Univ., ***International Christian Univ.)
[Bull. Chem. Soc. Jpn. 69, 3207 (1996)]
The orange and green forms of the Schiff base-oxovanadium(IV) complex, [VO{sal-(RR)-stien }]·MeOH (1, green), [VO{sal-(RR)-stien}]·2CHCl3 (2, green), and [VO{sal-(RR)-stien}]·CH3CN (3, orange) (H2{sal-(RR)-stien} =N,N'-disalicylidene-(RR)-I,2-diphenyl-I,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, (beta)=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, (alpha)=103.72(2), (beta) = 103.20(3), (gamma)=63.03(2)°, and V =1591.2(7) Å3. 3 crystallizes as triclinic in space group Pl with Z = 2. The cell parameters are a =13.300(3), b =13.667(4), c = 7.55 l(l) Å, a= 90.44(2), b= 94.51(2), g= 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.