Assignment of 31P Chemical Shifts to Isomers of 2,3-Dialkoxy-A3-diazadiphosphetidines — Crystal and Molecular Structure of rrflMs-[PhNP(OCH2CF3)]2
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چکیده
Geometrical isomers of /.3-diazadiphosphetidines show large differences in their 31P chemical shifts. Trifluoroethoxylation of rä-(PhNPC l) 2 gives only the 'low-field' isomer initially, for which the crystal structure is determined. The compound crystallises in the triclinic space group P 1 with a = 9 .624(4 ).6 = 10 .107(4),c = 11.140(7) Ä ;a = 105.65(4),ß = 110.59(4),y = 93 .82(3)°;and Z = 2. The structure was solved by direct methods and refined to R = 0.045. The alkoxy groups are trans to each other. On standing in solution. rra/J5 -[PhNP(OCH 2 CF3 ) ] 2 transforms slowly and almost com pletely into its cis analogue with a high field 31P chemical shift.
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تاریخ انتشار 2012