NOTES
Nov., 1962
2275
TABLE I Initial mixture
+
2Ra0 1VO1,to IISa3V~08 7Ba0 1BaO 2V01.00 113aaVz08 1V40 IllBaO WZOJ 51Ba0 3VO2 5Ba0 3Vz0a 71Ba0 ~VOZ
+ + + +
Reaction conditions
2 X
+ 3V
3 x 2 X 3 x
2 x 2 X 2 X 2 X
+ + +
l/e '/4
+ 72 hr., 1080" hr., 1270" + 150 hr., 1000"
hr., 1270"
hr., 1450' hr., 1220' hr., 1200" hr., 1200' hr., 1120" hr., 1230"
l/* 1/4
+ hr., 1,740" + 150 hr., 1000" + 150 hr., 1000° + 50 hr., 1130" + 170 hr., 1070"
in Table I while powder diagrams are presented in Fig. 1. For the preparation of the BaV203 phase considerably more severe prefiring was shown to be necessary when BaO and VO1 00 were employed as starting materials. A difference of the very weak reflections therefore remained even after prolonged annealing at various temperatures. Some very weak lines in patterns Fig. l g and h do not fit in patterns Fig. Id or i. The circumstances to obtain both Ba3V2Os and BaV203 in a good crystalline state apparently do not coincide: after annealing of a mixture 7Ba0 6V02 a t 1200' the Ba3V:!Os lines vanished leaving pattern Fig. Id. (No ipowder diagram of this sample is presented in Fig. 1.) However, a composition different from IBaVzO3is considered to be possible. I n two respects Ba-V-0 products are shown to be remarkable. First the non-existence of MI11 and MIV complexes a t temperatures higher than 1000° has proved to be in contrast with the systems Ba-M-0 in which h4 = Ti, Cr, hln, Fe. On the other hand no perovskite phases are formed in the Ba-Tr-O system, contrary to the A-V-0 systems in which A = Sr or Ca. Both Sr and Ca form perovskite compounds: Rudorff and Reuter' reported a Sr-V-0 phase of this structure which according to Kestigian, et uZ.,~ forms a t l l O O o and at compositions between Sr'VO2.60 and SrV02.,6, while Rudorff and Beckerg observed a Ca-V-0 perovskite. Magnetic measurements and closer X-ray -~ studies on the Ba2V03 and h V z 0 3 phases are being carried out in order to investigate the way in which the 3d electrons of the vanadium metal contribute to chemical bondings. The results will be described elsewhere. Acknowledgment.-The authors wish to express their gratitude to Professor Dr. A. E. van Arkel for his guidance in many stimulating discussions.
+
___.
(7) W. Rihlorff and B. Reuter, Z. anorg. allgem. Chem., 253, 177 (1947). (8) M. Xe'stigian, J. G. Dickinson, and R. Ward, J . A m , Chem. Sac., 79, 5598 (1957). (9) W. Rldorff and H. Becker, Z. Naturforsch., 9b, 613 (1954).
~ I / z
Appearance
Green Green Dark gray Black Gray Gray Gray Gray
Products
Ba2V03
B
X
BaVzOa BaVz03 lBarVxOs 4BazV08 1BarVzO~ 3-1 IBa31iz08 -k 2BaVzOs 2BasVz08 l m t
+ + +
doline-6'-nitrobenzopyrylospiran (I) by ultraviolet irradiation at room temperature.
It has recently been reported4 that electron spin resonance studies of the solid colored form I1 indicate an unpaired eIectron suggestive of I1 being a stable biradical or an ionic free radical. We have prepared solid I1 by two different routes : (1) by ultraviolet irradiation of a hexane solution of I, and (2) by treatment of a hydrochloride of I with aqueous alkali. The solid colored material produced by either route gave identical infrared absorption spectra (as Nujol mulls), thermally and photochemically reverted in solution to I, and melted a t 172--174' after becoming colorless a t about 15.5'. Electron spin resonance studies6 showed the absence of unpaired electrons in freshly prepared colored form 11. However, a sample of I1 which had been stored in the dark in air for several months gave a weak absorption (g = 2.0039 & 0.0001, v = 9405.4 Mc./sec.) probably due to peroxide formation. The author agrees with the proposal3 that the colored forms of spiropyrans are various geometric isomers of the merocyanine type and not biradicals. (1) Y. Hirshberg, J . A m . Chem. Soc., 78, 2304 (1956). (2) E. Berman, R. E. Fox, and F. D. Thomson, %bad.,81,5605 (1959). (3) R. Heiligman-Rim, Y. Hirshberg, and E. Fischer, J . Phys. Chem., in press. (4) C. A. Heller, D A. Fine, and R. A. Henry, zbid., 65, 1908 (1961). (5) Performed through the courtesy of Dr. Paul Dorain, Brandeis Univ.
EFFECT OF CROSS-LIKKIXG ON THE PROPERTIES OF CARBQXYLIC POLYMERS. 11. APPARENT DISSOClATION CONSTANTS AS A FUKCTIQN OF T H E EXCHANGING &IONOVALENT CATIOK
PHOTOCHROMIC SPIROPYRANS
BY ROBERT KTNINA N D SALLIEFISHER
:BY ELLIOT BERMAN
R o h m &- Haas Company, Philadelphia, Pa.
Chemistry Laboratory, Itek Corporation, Lexington, Maseachusetta
Received June 18, 1068
Received M a y 86, 1068
I n a previous paper* the authors presented data pertaining to the variation of the apparent dissociation constants of cross-linked polyacrylic and
Previous ~ o r k e r s l -in~ general. have proposed a merocyanine-like structure for the colored form I1 formed plnotochemically from 1,3,3-trimethylin-
(1)
S.Fisher and R. Kunin, J. Phys. Chem.,
60, 1030 (1956).
