organic compounds
Diethyl [2,2,2-trifluoro-1-phenylsulfonylamino-1-(trifluoromethyl)ethyl]phosphonate
aUniversity of Michigan, Toxicology Program, 1420 Washington Heights, Ann Arbor, MI 48109-2029, USA, bUniversity of Michigan, Department of Chemistry, 930 N. University, Ann Arbor, MI 48109-1055, USA, and cInstitute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russian Federation
*Correspondence e-mail: rjrich@umich.edu
The title compound, C13H16F6NO5PS, is of interest with respect to inhibition of serine hydrolases. Its structure contains a 1.8797 (13) Å P—C bond and two intermolecular N—H⋯O=P hydrogen bonds, resulting in centrosymmetric dimers. An intramolecular N—H⋯O=P hydrogen bond is also present.
Related literature
For related literature, see: Chekhlov et al. (1995); Makhaeva et al. (2005); Adams et al. (2008); Chen et al. (2008); Guo et al. (2008); Kachkovskyi & Kolodiazhnyi (2007); Liu et al. (1995).
Experimental
Crystal data
|
Refinement
|
Data collection: SMART (Bruker, 1998); cell SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536808020175/si2094sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808020175/si2094Isup2.hkl
The title compound was synthesized by mixing ether solutions of equimolar amounts of diethylphosphite and the sulfonylimine of hexafluoroacetone followed by subsequent recrystallization from petroleum ether.
Colorless plates of the ethyl analog were grown via evaporation from methanol at 22 °C. A crystal with dimensions of 0.60 × 0.42 × 0.40 mm was cut from a larger crystal and mounted on a standard Bruker SMART CCD-based X-ray diffractometer equipped with a LT-2 low temperature device and normal focus Mo-target X-ray tube (λ = 0.71073 Å) operated at 2000 W power (50 kV, 40 mA). X-ray intensities were measured at 113 (2) K with the detector placed 4.980 cm from the crystal. A total of 3030 frames were collected with a scan width of 0.3° in ω and ϕ and an exposure time of 20 sec/frame.
Data integration yielded a total of 20001 reflections to a maximum 2θ value of 56.58° of which 4568 were independent and 4343 were greater than 2 σ(I). The final cell constants were based on the xyz centroids of 6691 reflections above 10 σ(I).
The hydrogen atoms were treated as riding, with N—H distance = 0.88 Å and C—H distances in the range 0.95–0.99 Å with Uiso(H) = 1.2Ueq(N,C), 1.5Ueq(Cmethyl).
Data collection: SMART (Bruker, 1998); cell
SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C13H16F6NO5PS | F(000) = 904 |
Mr = 443.3 | Dx = 1.596 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 6567 reflections |
a = 11.6913 (15) Å | θ = 2.9–28.3° |
b = 10.1375 (13) Å | µ = 0.35 mm−1 |
c = 15.5955 (19) Å | T = 113 K |
β = 93.264 (2)° | Plate, colourless |
V = 1845.4 (4) Å3 | 0.60 × 0.42 × 0.40 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | 4568 independent reflections |
Radiation source: fine-focus sealed tube | 4027 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.022 |
ϕ and ω scans | θmax = 28.3°, θmin = 2.9° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | h = −15→15 |
Tmin = 0.820, Tmax = 0.874 | k = −13→13 |
20001 measured reflections | l = −20→20 |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.029 | w = 1/[σ2(Fo2) + (0.0427P)2 + 0.6948P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.082 | (Δ/σ)max = 0.001 |
S = 1.03 | Δρmax = 0.34 e Å−3 |
4568 reflections | Δρmin = −0.33 e Å−3 |
246 parameters |
C13H16F6NO5PS | V = 1845.4 (4) Å3 |
Mr = 443.3 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 11.6913 (15) Å | µ = 0.35 mm−1 |
b = 10.1375 (13) Å | T = 113 K |
c = 15.5955 (19) Å | 0.60 × 0.42 × 0.40 mm |
β = 93.264 (2)° |
Bruker SMART CCD area-detector diffractometer | 4568 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 4027 reflections with I > 2σ(I) |
Tmin = 0.820, Tmax = 0.874 | Rint = 0.022 |
20001 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.082 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.34 e Å−3 |
4568 reflections | Δρmin = −0.33 e Å−3 |
246 parameters |
Experimental. 2103 frames × 20 sec @ 4.980 cm; 0.3 ° scans in ω & ϕ |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
P1 | 0.64284 (3) | 0.17485 (3) | 0.04487 (2) | 0.02726 (9) | |
S1 | 0.33796 (3) | 0.15018 (3) | 0.174771 (18) | 0.02622 (8) | |
N1 | 0.46059 (9) | 0.12554 (10) | 0.13045 (6) | 0.0247 (2) | |
H1A | 0.4569 | 0.0699 | 0.0870 | 0.030* | |
F1 | 0.73735 (8) | 0.14398 (10) | 0.24829 (6) | 0.0445 (2) | |
F2 | 0.66649 (8) | −0.02537 (9) | 0.17986 (5) | 0.0429 (2) | |
F3 | 0.57711 (8) | 0.05961 (9) | 0.28299 (5) | 0.0412 (2) | |
F4 | 0.56725 (9) | 0.33003 (9) | 0.27115 (5) | 0.0434 (2) | |
F5 | 0.67125 (8) | 0.38612 (9) | 0.16867 (6) | 0.0415 (2) | |
F6 | 0.48768 (7) | 0.39288 (8) | 0.14967 (5) | 0.03547 (19) | |
C1 | 0.26341 (11) | 0.26504 (13) | 0.10763 (7) | 0.0255 (2) | |
C2 | 0.24216 (12) | 0.23293 (14) | 0.02114 (8) | 0.0307 (3) | |
H2A | 0.2676 | 0.1513 | −0.0009 | 0.037* | |
C3 | 0.18337 (14) | 0.32241 (16) | −0.03191 (9) | 0.0398 (3) | |
H3A | 0.1682 | 0.3022 | −0.0909 | 0.048* | |
C4 | 0.14648 (15) | 0.44131 (17) | 0.00055 (9) | 0.0435 (4) | |
H4A | 0.1074 | 0.5028 | −0.0366 | 0.052* | |
C5 | 0.16614 (14) | 0.47135 (16) | 0.08707 (9) | 0.0402 (3) | |
H5A | 0.1391 | 0.5522 | 0.1091 | 0.048* | |
C6 | 0.22553 (12) | 0.38277 (14) | 0.14136 (8) | 0.0313 (3) | |
H6A | 0.2399 | 0.4026 | 0.2005 | 0.038* | |
C7 | 0.57400 (11) | 0.18007 (12) | 0.15084 (8) | 0.0258 (2) | |
C8 | 0.57452 (12) | 0.32405 (14) | 0.18606 (9) | 0.0326 (3) | |
C9 | 0.63978 (13) | 0.08914 (14) | 0.21698 (9) | 0.0342 (3) | |
C10 | 0.86488 (14) | 0.16185 (18) | 0.02046 (12) | 0.0464 (4) | |
H10A | 0.8876 | 0.2351 | −0.0170 | 0.056* | |
H10B | 0.8423 | 0.0853 | −0.0161 | 0.056* | |
C11 | 0.96179 (17) | 0.1256 (3) | 0.08278 (18) | 0.0793 (7) | |
H11A | 0.9820 | 0.2017 | 0.1194 | 0.119* | |
H11B | 1.0283 | 0.0995 | 0.0512 | 0.119* | |
H11C | 0.9386 | 0.0519 | 0.1186 | 0.119* | |
C12 | 0.50917 (13) | 0.29279 (16) | −0.07438 (9) | 0.0367 (3) | |
H12A | 0.4590 | 0.3713 | −0.0728 | 0.044* | |
H12B | 0.4613 | 0.2134 | −0.0674 | 0.044* | |
C13 | 0.56368 (16) | 0.28690 (17) | −0.15912 (10) | 0.0455 (4) | |
H13A | 0.6155 | 0.3622 | −0.1640 | 0.068* | |
H13B | 0.5040 | 0.2901 | −0.2058 | 0.068* | |
H13C | 0.6071 | 0.2046 | −0.1628 | 0.068* | |
O1 | 0.27788 (9) | 0.02744 (10) | 0.16554 (6) | 0.0339 (2) | |
O2 | 0.36007 (9) | 0.20787 (10) | 0.25771 (5) | 0.0346 (2) | |
O3 | 0.61539 (8) | 0.04887 (9) | 0.00278 (6) | 0.0311 (2) | |
O4 | 0.77052 (9) | 0.20205 (12) | 0.07141 (7) | 0.0435 (3) | |
O5 | 0.59785 (9) | 0.29985 (10) | −0.00394 (6) | 0.0348 (2) |
U11 | U22 | U33 | U12 | U13 | U23 | |
P1 | 0.02908 (17) | 0.02691 (17) | 0.02539 (16) | 0.00270 (12) | −0.00198 (12) | −0.00504 (12) |
S1 | 0.03576 (17) | 0.02732 (16) | 0.01571 (13) | 0.00577 (12) | 0.00261 (11) | 0.00207 (10) |
N1 | 0.0305 (5) | 0.0241 (5) | 0.0192 (4) | 0.0051 (4) | −0.0018 (4) | −0.0048 (4) |
F1 | 0.0422 (5) | 0.0527 (5) | 0.0364 (4) | 0.0091 (4) | −0.0185 (4) | −0.0058 (4) |
F2 | 0.0575 (5) | 0.0330 (4) | 0.0363 (4) | 0.0205 (4) | −0.0127 (4) | −0.0031 (3) |
F3 | 0.0557 (5) | 0.0430 (5) | 0.0236 (4) | 0.0084 (4) | −0.0093 (4) | 0.0041 (3) |
F4 | 0.0591 (6) | 0.0422 (5) | 0.0277 (4) | 0.0078 (4) | −0.0074 (4) | −0.0163 (3) |
F5 | 0.0415 (5) | 0.0342 (5) | 0.0479 (5) | −0.0042 (4) | −0.0065 (4) | −0.0146 (4) |
F6 | 0.0423 (4) | 0.0229 (4) | 0.0404 (4) | 0.0082 (3) | −0.0050 (3) | −0.0057 (3) |
C1 | 0.0292 (6) | 0.0292 (6) | 0.0181 (5) | 0.0059 (5) | 0.0025 (4) | 0.0009 (4) |
C2 | 0.0388 (7) | 0.0329 (7) | 0.0202 (5) | 0.0110 (5) | 0.0005 (5) | −0.0027 (5) |
C3 | 0.0523 (9) | 0.0449 (8) | 0.0215 (6) | 0.0175 (7) | −0.0052 (6) | −0.0026 (5) |
C4 | 0.0550 (9) | 0.0439 (8) | 0.0304 (7) | 0.0243 (7) | −0.0075 (6) | 0.0003 (6) |
C5 | 0.0500 (8) | 0.0379 (8) | 0.0320 (7) | 0.0214 (7) | −0.0022 (6) | −0.0062 (6) |
C6 | 0.0371 (7) | 0.0346 (7) | 0.0222 (5) | 0.0100 (5) | 0.0012 (5) | −0.0042 (5) |
C7 | 0.0319 (6) | 0.0237 (6) | 0.0210 (5) | 0.0065 (5) | −0.0062 (4) | −0.0044 (4) |
C8 | 0.0386 (7) | 0.0287 (6) | 0.0294 (6) | 0.0053 (5) | −0.0067 (5) | −0.0091 (5) |
C9 | 0.0412 (7) | 0.0339 (7) | 0.0261 (6) | 0.0100 (6) | −0.0105 (5) | −0.0032 (5) |
C10 | 0.0367 (8) | 0.0492 (9) | 0.0545 (10) | −0.0068 (7) | 0.0128 (7) | −0.0050 (7) |
C11 | 0.0352 (9) | 0.110 (2) | 0.0913 (17) | 0.0118 (11) | −0.0041 (10) | −0.0132 (15) |
C12 | 0.0365 (7) | 0.0387 (8) | 0.0345 (7) | 0.0026 (6) | −0.0009 (5) | 0.0107 (6) |
C13 | 0.0660 (11) | 0.0390 (8) | 0.0318 (7) | 0.0067 (7) | 0.0048 (7) | 0.0056 (6) |
O1 | 0.0433 (5) | 0.0309 (5) | 0.0280 (4) | −0.0005 (4) | 0.0077 (4) | 0.0054 (4) |
O2 | 0.0497 (6) | 0.0391 (5) | 0.0150 (4) | 0.0111 (4) | 0.0014 (4) | −0.0011 (4) |
O3 | 0.0386 (5) | 0.0286 (5) | 0.0259 (4) | 0.0044 (4) | 0.0006 (4) | −0.0070 (4) |
O4 | 0.0289 (5) | 0.0543 (7) | 0.0466 (6) | 0.0028 (5) | −0.0028 (4) | −0.0166 (5) |
O5 | 0.0443 (6) | 0.0288 (5) | 0.0308 (5) | −0.0027 (4) | −0.0012 (4) | 0.0026 (4) |
P1—O3 | 1.4632 (10) | C4—C5 | 1.390 (2) |
P1—O4 | 1.5509 (11) | C4—H4A | 0.9500 |
P1—O5 | 1.5545 (10) | C5—C6 | 1.3923 (19) |
P1—C7 | 1.8797 (13) | C5—H5A | 0.9500 |
S1—O2 | 1.4296 (9) | C6—H6A | 0.9500 |
S1—O1 | 1.4321 (11) | C7—C9 | 1.5539 (17) |
S1—N1 | 1.6458 (11) | C7—C8 | 1.5594 (17) |
S1—C1 | 1.7629 (12) | C10—O4 | 1.4540 (19) |
N1—C7 | 1.4549 (16) | C10—C11 | 1.496 (3) |
N1—H1A | 0.8800 | C10—H10A | 0.9900 |
F1—C9 | 1.3361 (17) | C10—H10B | 0.9900 |
F2—C9 | 1.3419 (16) | C11—H11A | 0.9800 |
F3—C9 | 1.3313 (18) | C11—H11B | 0.9800 |
F4—C8 | 1.3359 (16) | C11—H11C | 0.9800 |
F5—C8 | 1.3354 (18) | C12—O5 | 1.4687 (17) |
F6—C8 | 1.3320 (16) | C12—C13 | 1.501 (2) |
C1—C6 | 1.3870 (18) | C12—H12A | 0.9900 |
C1—C2 | 1.3960 (16) | C12—H12B | 0.9900 |
C2—C3 | 1.3838 (18) | C13—H13A | 0.9800 |
C2—H2A | 0.9500 | C13—H13B | 0.9800 |
C3—C4 | 1.386 (2) | C13—H13C | 0.9800 |
C3—H3A | 0.9500 | ||
O3—P1—O4 | 117.26 (6) | F6—C8—F5 | 107.48 (12) |
O3—P1—O5 | 115.62 (6) | F6—C8—F4 | 108.02 (11) |
O4—P1—O5 | 106.23 (6) | F5—C8—F4 | 106.43 (11) |
O3—P1—C7 | 108.97 (6) | F6—C8—C7 | 110.65 (10) |
O4—P1—C7 | 102.36 (6) | F5—C8—C7 | 110.84 (11) |
O5—P1—C7 | 104.94 (6) | F4—C8—C7 | 113.15 (11) |
O2—S1—O1 | 120.58 (6) | F3—C9—F1 | 107.88 (11) |
O2—S1—N1 | 108.97 (6) | F3—C9—F2 | 106.91 (12) |
O1—S1—N1 | 105.06 (6) | F1—C9—F2 | 107.63 (12) |
O2—S1—C1 | 108.97 (6) | F3—C9—C7 | 111.92 (11) |
O1—S1—C1 | 106.92 (6) | F1—C9—C7 | 112.07 (12) |
N1—S1—C1 | 105.30 (5) | F2—C9—C7 | 110.20 (10) |
C7—N1—S1 | 130.95 (8) | O4—C10—C11 | 106.50 (16) |
C7—N1—H1A | 114.5 | O4—C10—H10A | 110.4 |
S1—N1—H1A | 114.5 | C11—C10—H10A | 110.4 |
C6—C1—C2 | 121.60 (11) | O4—C10—H10B | 110.4 |
C6—C1—S1 | 120.05 (9) | C11—C10—H10B | 110.4 |
C2—C1—S1 | 118.34 (10) | H10A—C10—H10B | 108.6 |
C3—C2—C1 | 118.67 (12) | C10—C11—H11A | 109.5 |
C3—C2—H2A | 120.7 | C10—C11—H11B | 109.5 |
C1—C2—H2A | 120.7 | H11A—C11—H11B | 109.5 |
C2—C3—C4 | 120.41 (13) | C10—C11—H11C | 109.5 |
C2—C3—H3A | 119.8 | H11A—C11—H11C | 109.5 |
C4—C3—H3A | 119.8 | H11B—C11—H11C | 109.5 |
C3—C4—C5 | 120.51 (13) | O5—C12—C13 | 110.09 (13) |
C3—C4—H4A | 119.7 | O5—C12—H12A | 109.6 |
C5—C4—H4A | 119.7 | C13—C12—H12A | 109.6 |
C4—C5—C6 | 119.89 (13) | O5—C12—H12B | 109.6 |
C4—C5—H5A | 120.1 | C13—C12—H12B | 109.6 |
C6—C5—H5A | 120.1 | H12A—C12—H12B | 108.2 |
C1—C6—C5 | 118.90 (12) | C12—C13—H13A | 109.5 |
C1—C6—H6A | 120.5 | C12—C13—H13B | 109.5 |
C5—C6—H6A | 120.5 | H13A—C13—H13B | 109.5 |
N1—C7—C9 | 109.28 (11) | C12—C13—H13C | 109.5 |
N1—C7—C8 | 114.70 (10) | H13A—C13—H13C | 109.5 |
C9—C7—C8 | 109.24 (10) | H13B—C13—H13C | 109.5 |
N1—C7—P1 | 103.16 (8) | C10—O4—P1 | 123.57 (10) |
C9—C7—P1 | 110.27 (9) | C12—O5—P1 | 122.10 (9) |
C8—C7—P1 | 110.04 (9) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O3 | 0.88 | 2.34 | 2.8730 (14) | 119 |
N1—H1A···O3i | 0.88 | 2.00 | 2.8324 (14) | 158 |
Symmetry code: (i) −x+1, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | C13H16F6NO5PS |
Mr | 443.3 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 113 |
a, b, c (Å) | 11.6913 (15), 10.1375 (13), 15.5955 (19) |
β (°) | 93.264 (2) |
V (Å3) | 1845.4 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.35 |
Crystal size (mm) | 0.60 × 0.42 × 0.40 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.820, 0.874 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 20001, 4568, 4027 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.666 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.082, 1.03 |
No. of reflections | 4568 |
No. of parameters | 246 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.33 |
Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 2003), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O3 | 0.88 | 2.34 | 2.8730 (14) | 119.0 |
N1—H1A···O3i | 0.88 | 2.00 | 2.8324 (14) | 157.7 |
Symmetry code: (i) −x+1, −y, −z. |
Footnotes
‡Deceased.
Acknowledgements
The authors thank NIH (ES07062), CRDF (RB2-2035 and RB2-2488) and ARO (DAAD19-02-1-0388) for financial support.
References
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Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
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The title compound is a member of the fluorinated α-aminophosphonate (FAP) group of compounds [(RO)2P(O)C(CF3)2NHS(O)2C6H5; R = CH3, C2H5, C3H7, iso-C3H7, n-C4H9, iso-C4H9, iso-C5H11, n-C5H11, and n-C6H13] that have been synthesized and used in biochemical studies as inhibitors of serine hydrolases (Chekhlov et al., 1995; Makhaeva et al., 2005). These studies suggested the hypothesis that inhibition of serine hydrolases by FAP compounds occurs via scission of the P—C bond to organophosphorylate the active site serine (Makhaeva et al., 2005). Although P—C bonds are exceptionally stable in most phosphonates, enzymes such as bacterial carbon-phosphorus lyase are capable of catalyzing their cleavage, thus providing a potential method for destroying toxic phosphonates that might otherwise accumulate in the environment (Adams et al., 2008). Moreover, the structure of diisopentyl-FAP revealed a 1.888 (4) Å P—C bond (Chekhlov et al., 1995), which was calculated to be longer and weaker than P—C bonds in phosphonates lacking adjacent –CF3 groups (Makhaeva et al., 2005).
To provide a further test of our hypothesis, the X-ray crystal structure of the title compound was determined (Fig 1). The title compound contains an intramolecular P=O···H—N hydrogen bond (Fig. 1; Table 1), and in the crystal it is linked via two intermolecular P=O···H—N hydrogen bonds to form inversion-related dimers (Fig. 2; Table 1). As predicted, the structure of diethyl-FAP revealed an elongated P—C bond that was 1.8797 (13) Å in length, which is not significantly different from the 1.888 (4) Å P—C bond in diisopentyl-FAP (Chekhlov et al., 1995). This is long compared to P—C bond lengths of 1.822 (2) Å (Chen et al., 2008), 1.803 (4) Å (Guo et al., 2008), 1.818 (5) Å (Kachkovskyi and Kolodiazhnyi, 2007), and 1.805 (6) Å (Liu et al., 1995) reported for the crystal structures of a variety of dialkyl phosphonates lacking α-CF3 groups. The long P—C bond in diethyl-FAP is expected to be labile and would explain the ability of the compound to organophosphorylate and inhibit serine hydrolases as well as their ability to undergo hydrolysis to yield phosphoric acid diethyl ester and the amide, (CF3)2CH–NH–SO2–C6H5 (Makhaeva et al., 2005).