The 17O NMR spectra for aryl-substituted P,P-diphenylbenzoylphosphanes (p-YC6H4COPPh2, 1), trimethylbenzoylsilanes (p-YC6H4COSiMe3, 2) and dialkyl benzoylphosphonates (p-YC6H4COPO(OR)2, 3) were recorded. Compounds 1, 2 and 3 show a similar high substituent sensitivity (p+), indicating a strong electron demand of the carbonyl group; as resonance stabilization is not possible in 2 and 3 it is concluded that electron donation from P to carbonyl is equally negligible in 1. The carbonyl oxygen signals of 1, 3 and, in particular, 2 appear at low field. The 31P NMR shifts of 1 were also measured; they are less sensitive to the ring substituents.
记录了芳基取代的 P,P-二苯基苯甲酰膦(p-YC6H4C
OPPh2,1)、三甲基苯甲酰
硅烷(p-YC6H4COSiMe3,2)和二烷基苯甲酰
膦酸盐(p-YC6H4
COPO(OR)2,3)的 17O NMR 光谱。化合物 1、2 和 3 显示出类似的高取代基灵敏度 (p+),表明羰基对电子的需求量很大;由于在 2 和 3 中无法实现共振稳定,因此可以得出结论:在 1 中,从 P 到羰基的电子捐赠同样可以忽略不计。还测量了 1 的 31P NMR 移位;它们对环状取代基不那么敏感。