loss of intensity was observed during the experiment as judged by regular monitoring of three reference reflections so that a single scale factor could be used. No corrections for absorption were deemed necessary.Crystal Data for o-Bromobenzoate 6.-CijHaiBrO, had formula weight 547.4, orthorhombic, a = 11.25 (2), b = 26.63 (4), c = 8.96 (2) A, U = 2685 Á8, Dm = 1.34 (by pycnometry with an aqueous Znl solution), Z = 4, £)" = 1.35, F (000) = 1136. Space group P2i2i2i. Precession photography, Mo Ka radiation, X 0.7107 Á, µ 17 cm-1.Structure Determination and Refinement.-The structure was solved by the heavy-atom method in the usual way, and five cycles of Fourier refinement with a single, overall, isotropic thermal parameter, B = 4.0 A2, gave B = 0.22.Further refinement of the structural parameters was by blockdiagonal least-squares methods. With anisotropic thermal parameters assumed only for the bromine atom, B was 0.118 at convergence. Inclusion of the anomalous dispersion terms16 for bromine in the structure factor calculations gave B = 0.123 and 0.116 for the two possible enantiomeric structures. By Hamilton's ñ-factor ratio test17 a significant distinction is implied between the two absolute configurations at the 99.5% confidence (16) D.
Die Phospholenoxide (I) reagieren nach Lithiierung mit n‐Butyllithium mit CO2 zu den Säuren (II), die auf verschiedenen Wegen zu den Estern (III) umgesetzt und nach Hydrierung zu den entsprechenden Phospholanen mit Trichlorsilan zu den Phosphinen (IV) reduziert werden.
Abstract-The 13C-31P coupling constant is much larger for a 2-methyl substituent (about 20 Hz) than for a 3-methyl substituent (about 5 Hz) in phospholes and 2-phospholenes, and appears useful for assigning structures in these compounds.IN THE interpretation of the NMR spectrum of I-methylphosphole,l we proposed that 31P coupling with the proton at the 2-position [2J(P-H)] was more extensive (38-5 us. 13.8 Hz) than with the 3-pr0ton[~J(P-H)]. Although this view was the opposite of that commonly held for P-H coupling in phosphines, it has been fully substantiated in later work2 and also found applicable to the 2-phospholene ~y s t e m .~ In the course of an examination of the I3C NMR properties of phospholes and phospholenes, we have discovered that the same relation is true for 31P coupling with 13C of methyls attached to sp2 carbon; 2J(P-C) is considerably larger than 3J(P-C). This specificity is unusual, for in acyclic phosphines 2J(P-C) and 3J(P-C) (as well as 'J(P-C)) are of similar magnitude and little structural information
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