Ph_3 As+CH_2 COO-·1 1/2H_2O的晶体和分子结构

The Crystal and Molecular Structure of Carboxylmethyl Triphenylarsonium Salt, Ph_3 As+CH_2 COO-·1 1/2H_2O

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Colorless transparent crystals of an inner salt of carboxylmethyl triphenylarsonium Ph_3As^+CH_2COO- 11/2H_2O, the hydrolytic product of carbomethoxymethylene triphenylarsorane, were obtained from CH_3OH:C_2H_5OH (1:2) solution. Space group P , a=9. 430(1),b=9. 544 (1), c=20.797(1) , a=97.62(1), β=97.42(1),γ=99.23(1)°,V=1809.2 ,Z=4,D_o= 1.436g/cm^3. The structure was Solved by the heavy-atom method and refined by the full- matrix least-squares method with anisotropic temperature factors for non-hydrogen atoms and isotropic for all hydrogen atoms to R=0.030. The results show that the bond length As-CH_2 is comparable to the three As-Ph bond lengths and the carboxyl is delocalized. These differ obviously from those of arsonium ylides reported. The possible mechanism of the hydrolysis process was also suggested.