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The crystal and molecular structure of pentafluoropropionylbenzoylmethylene triphenylphosphorane
Author(s) -
ZongXiang Xia,
ZhiMing Zhang,
YanChang Shen
Publication year - 1984
Publication title -
acta chimica sinica english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 0256-7660
DOI - 10.1002/cjoc.19840020207
Subject(s) - chemistry , crystal structure , crystal (programming language) , crystallography , programming language , computer science
Abstract The crystals of pentafluoropropionylbenzoylmethylene triphenylphosphorane that bears two strongly electron‐withdrawing groups in alkylidene moiety are monoclinic and its space group is C 2/ c , with a = 11.271(3)Å, b = 18.253(6)Å, c =23.938(7)Å, β = 91.09(2)°, z = 8. The X‐ray diffraction intensity data were collected on a four‐circle diffractometer. The structure has been solved by direct method and refined by block‐diagonal least‐squares method. The final R ‐ index was 0.075 for 3146 independent observed reflexions. In this paper the structure of this ylide is compared with that of corresponding arsonium ylide previously reported. Both ylidic skeleton structures are planar with sp 2 hybridization. The bond length of P‐C(1) is 1.748 (5)Å with bond order. 1.60 while the bond order of As‐C(1) in the corresponding arsonium ylide is 1.46, indicating that the phosphonium ylide has a greater contribution of “ylene” structure to the overall structure. As a result the phosphonium ylide should be less reactive than the corresponding arsonium ylide. In both ylides, (he major delocalized canonical forms of negative charge are shown to be 3.