Griffin, C. E. published the artcilePhosphoryl stretching frequency correlation for phosphonic acid derivatives, Quality Control of 66197-72-6, the publication is Chemistry & Industry (London, United Kingdom) (1960), 1058-9, database is CAplus.
A plot of Σ σ* (Taft substituent constants) vs. γPO (as films in CS2 or CCl4) for 19 phosphonates [RP(O)XY] (I) gave a linear relationship; a least squares treatment of the data gave γPO = 16.80 Σσ* + 1198. The following I were studied (X = Y = OEt) (R given): Me, Et, Pr, Bu, n-C6H13, CH2:CH, CH2:CHCH2, PhCH2, Ph, ClCH2, Cl2CH, CCl3 (II), BrCH2, HOCH2, AcCH2. Also I (R, X, and Y given): Me, OMe, OMe; Me, OEt, NMe2; Me, NMe2, NMe2 (III); Ph, H, OEt. The average deviation between calculated and observed frequencies was ±4 cm.-1; the only significant deviation occurred with II and III, and may have arisen through disturbance of the normal inductive effects of the substituents by field effects. Major deviations from the linear relationship also occurred with frequency values obtained in the presence of H-bonding solvents. The following σ* values were tentatively assigned: (CH2)2CO2Et, 0.39; (CH2)3CO2Et, 0.39; NEt2, 0.68.
Chemistry & Industry (London, United Kingdom) published new progress about 66197-72-6. 66197-72-6 belongs to bromides-buliding-blocks, auxiliary class Aliphatic Chain, name is Diethyl (bromomethyl)phosphonate, and the molecular formula is C5H12BrO3P, Quality Control of 66197-72-6.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary