Philip Coppens tribute
Joint refinement of X-ray and polarized neutron diffraction data has been carried out in order to determine charge and spin density distributions simultaneously in the nitronyl nitroxide (NN) free radical Nit(SMe)Ph. For comparison purposes, density functional theory (DFT) and complete active-space self-consistent field (CASSCF) theoretical calculations were also performed. Experimentally derived charge and spin densities show significant differences between the two NO groups of the NN function that are not observed from DFT theoretical calculations. On the contrary, CASSCF calculations exhibit the same fine details as observed in spin-resolved joint refinement and a clear asymmetry between the two NO groups.
Keywords: charge and spin densities; X-ray and polarized neutron diffraction; joint refinement; DFT and CASSCF calculations; nitronyl nitroxide free radical.
Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520617008241/xf5001sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520617008241/xf5001Isup2.hkl | |
Portable Document Format (PDF) file https://doi.org/10.1107/S2052520617008241/xf5001sup3.pdf |
CCDC reference: 1553900
Computing details top
(I) top
Crystal data top
C28H38N4O4S2 | F(000) = 596 |
MONOCLINIC, | Dx = 1.305 Mg m−3 |
a = 9.34 Å | Mo Kα radiation, λ = 0.71073 Å |
b = 19.482 Å | µ = 0.23 mm−1 |
c = 8.634 Å | T = 293 K |
β = 115.13° | Spherical, colorless |
V = 1422.4 Å3 | 0.12 × 0.11 × 0.1 mm |
Z = 2 |
Data collection top
8800 independent reflections | θmax = 40.3°, θmin = 2.6° |
7301 reflections with I > 2σ(I) |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | ||
S | 0.255160 (10) | 0.533470 (10) | 0.477150 (10) | 0.02244 (4) | |
O2 | 0.30684 (4) | 0.71903 (3) | −0.14381 (4) | 0.02690 (10) | |
O1 | 0.29505 (4) | 0.874580 (10) | 0.25753 (3) | 0.02480 (10) | |
N2 | 0.30117 (4) | 0.77492 (2) | −0.06913 (4) | 0.01820 (10) | |
N1 | 0.29036 (3) | 0.84854 (2) | 0.11910 (4) | 0.01710 (10) | |
C1 | 0.30447 (4) | 0.78121 (2) | 0.08832 (4) | 0.01580 (10) | |
C2 | 0.30795 (4) | 0.72411 (2) | 0.19885 (4) | 0.01540 (10) | |
C7 | 0.37939 (4) | 0.66139 (2) | 0.19219 (4) | 0.01740 (10) | |
C6 | 0.36578 (4) | 0.60520 (2) | 0.28365 (5) | 0.01760 (10) | |
C5 | 0.27731 (4) | 0.60962 (2) | 0.38032 (4) | 0.01670 (10) | |
C4 | 0.21125 (4) | 0.67264 (2) | 0.39262 (4) | 0.0202 (2) | |
C3 | 0.22810 (4) | 0.72950 (2) | 0.30408 (5) | 0.01870 (10) | |
C9 | 0.30051 (4) | 0.84340 (2) | −0.14955 (4) | 0.01780 (10) | |
C8 | 0.24759 (4) | 0.89124 (2) | −0.03905 (4) | 0.01630 (10) | |
C12 | 0.33259 (5) | 0.95994 (2) | 0.00754 (5) | 0.02470 (10) | |
C10 | 0.06903 (5) | 0.90237 (2) | −0.11262 (6) | 0.02520 (10) | |
C11 | 0.47000 (5) | 0.85696 (3) | −0.12594 (6) | 0.0310 (2) | |
C13 | 0.18925 (6) | 0.84061 (2) | −0.33844 (5) | 0.0275 (2) | |
C14 | 0.14777 (5) | 0.56097 (2) | 0.59714 (5) | 0.0284 (2) | |
H7 | 0.4473 (7) | 0.65479 (3) | 0.1206 (7) | 0.0400 (4) | |
H6 | 0.4225 (7) | 0.5575 (3) | 0.2830 (7) | 0.0417 (4) | |
H4 | 0.1428 (7) | 0.6771 (3) | 0.4654 (8) | 0.0423 (4) | |
H3 | 0.1707 (8) | 0.7766 (3) | 0.3083 (8) | 0.0377 (4) | |
H121 | 0.4549 (8) | 0.9506 (2) | 0.0823 (9) | 0.0477 (5) | |
H122 | 0.3264 (8) | 0.9850 (3) | −0.1059 (8) | 0.0403 (5) | |
H123 | 0.2773 (8) | 0.9922 (3) | 0.0692 (9) | 0.0513 (5) | |
H101 | 0.0349 (7) | 0.9336 (4) | −0.2264 (9) | 0.0470 (5) | |
H102 | 0.0393 (8) | 0.92814 (4) | −0.0178 (8) | 0.0510 (4) | |
H103 | 0.0066 (7) | 0.8548 (3) | −0.1394 (8) | 0.0420 (5) | |
H111 | 0.5506 (7) | 0.8599 (4) | 0.0065 (8) | 0.0407 (4) | |
H112 | 0.4722 (8) | 0.9031 (4) | −0.1912 (9) | 0.0507 (5) | |
H113 | 0.4996 (9) | 0.8152 (4) | −0.1889 (10) | 0.0587 (5) | |
H131 | 0.1778 (8) | 0.8908 (4) | −0.3982 (8) | 0.0470 (5) | |
H132 | 0.2324 (9) | 0.8045 (4) | −0.4017 (8) | 0.0533 (5) | |
H133 | 0.0762 (9) | 0.8215 (4) | −0.3555 (8) | 0.0463 (4) | |
H141 | 0.0363 (8) | 0.5831 (4) | 0.5088 (9) | 0.0550 (5) | |
H142 | 0.2147 (8) | 0.5966 (4) | 0.6947 (8) | 0.0533 (5) | |
H143 | 0.1352 (9) | 0.5152 (4) | 0.6595 (9) | 0.0520 (5) |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
S | 0.02991 (5) | 0.01742 (5) | 0.01998 (5) | −0.00415 (3) | 0.00859 (4) | 0.00219 (3) |
O2 | 0.0379 (2) | 0.02110 (10) | 0.02170 (10) | 0.00380 (10) | 0.01630 (10) | −0.00150 (10) |
O1 | 0.0365 (2) | 0.01820 (10) | 0.01980 (10) | −0.00160 (10) | 0.01510 (10) | −0.00200 (10) |
N2 | 0.02160 (10) | 0.01740 (10) | 0.01570 (10) | 0.00180 (10) | 0.00940 (10) | 0.00060 (10) |
N1 | 0.02080 (10) | 0.01460 (10) | 0.01600 (10) | −0.00020 (10) | 0.00890 (10) | 0.00050 (10) |
C1 | 0.01710 (10) | 0.01510 (10) | 0.01530 (10) | 0.00070 (10) | 0.00790 (10) | 0.00140 (10) |
C2 | 0.01580 (10) | 0.01480 (10) | 0.01580 (10) | 0.00080 (10) | 0.00760 (10) | 0.00130 (10) |
C7 | 0.01740 (10) | 0.0160 (2) | 0.01890 (10) | 0.00150 (10) | 0.00940 (10) | 0.00090 (10) |
C6 | 0.01900 (10) | 0.01470 (10) | 0.0191 (2) | 0.00150 (10) | 0.00770 (10) | 0.00100 (10) |
C5 | 0.01900 (10) | 0.01550 (10) | 0.01570 (10) | −0.00160 (10) | 0.00620 (10) | 0.00100 (10) |
C4 | 0.0228 (2) | 0.0179 (2) | 0.0199 (2) | 0.00050 (10) | 0.01270 (10) | 0.0020 (2) |
C3 | 0.0206 (2) | 0.01630 (10) | 0.0191 (2) | 0.00220 (10) | 0.0116 (2) | 0.00190 (10) |
C9 | 0.01840 (10) | 0.0201 (2) | 0.01500 (10) | 0.00150 (10) | 0.00690 (10) | 0.00340 (10) |
C8 | 0.01600 (10) | 0.01530 (10) | 0.01760 (10) | −0.00090 (10) | 0.00670 (10) | 0.00230 (10) |
C12 | 0.0308 (2) | 0.0199 (2) | 0.0236 (2) | −0.00810 (10) | 0.0106 (2) | 0.00020 (10) |
C10 | 0.0181 (2) | 0.0249 (2) | 0.0326 (2) | 0.00460 (10) | 0.0106 (4) | 0.0083 (2) |
C11 | 0.0241 (2) | 0.0332 (2) | 0.0358 (2) | 0.0038 (2) | 0.0194 (2) | 0.0098 (2) |
C13 | 0.0383 (2) | 0.0289 (2) | 0.0154 (2) | 0.0031 (2) | 0.0044 (2) | 0.00190 (10) |
C14 | 0.0324 (2) | 0.0307 (2) | 0.0221 (2) | −0.0099 (2) | 0.0132 (2) | 0.0013 (2) |
H7 | 0.044 (4) | 0.035 (4) | 0.041 (4) | 0.010 (3) | 0.031 (3) | 0.005 (3) |
H6 | 0.054 (4) | 0.020 (4) | 0.051 (4) | 0.011 (3) | 0.029 (3) | 0.006 (3) |
H4 | 0.048 (4) | 0.035 (4) | 0.044 (4) | 0.000 (3) | 0.034 (3) | 0.001 (3) |
H3 | 0.047 (4) | 0.025 (4) | 0.041 (4) | 0.007 (3) | 0.030 (4) | 0.003 (3) |
H121 | 0.039 (5) | 0.048 (5) | 0.056 (5) | −0.005 (4) | 0.010 (4) | 0.015 (4) |
H122 | 0.057 (5) | 0.029 (4) | 0.035 (4) | −0.006 (3) | 0.019 (4) | 0.010 (3) |
H123 | 0.065 (5) | 0.028 (4) | 0.061 (5) | −0.005 (4) | 0.035 (4) | −0.012 (4) |
H101 | 0.043 (4) | 0.049 (5) | 0.049 (5) | 0.005 (3) | 0.023 (4) | 0.019 (4) |
H102 | 0.045 (4) | 0.058 (5) | 0.050 (5) | 0.016 (4) | 0.027 (4) | 0.005 (4) |
H103 | 0.029 (4) | 0.041 (5) | 0.056 (5) | 0.001 (3) | 0.012 (3) | 0.013 (4) |
H111 | 0.023 (4) | 0.071 (5) | 0.028 (4) | −0.001 (3) | 0.006 (3) | 0.009 (4) |
H112 | 0.041 (4) | 0.049 (5) | 0.062 (5) | −0.001 (3) | 0.028 (4) | 0.029 (4) |
H113 | 0.058 (5) | 0.049 (5) | 0.069 (5) | 0.001 (4) | 0.042 (4) | 0.010 (4) |
H131 | 0.067 (5) | 0.038 (5) | 0.036 (4) | 0.001 (4) | 0.016 (4) | 0.012 (4) |
H132 | 0.081 (6) | 0.054 (5) | 0.034 (4) | 0.019 (4) | 0.027 (4) | −0.002 (4) |
H133 | 0.054 (5) | 0.048 (5) | 0.037 (4) | −0.006 (4) | 0.012 (4) | −0.014 (3) |
H141 | 0.045 (4) | 0.067 (5) | 0.053 (5) | −0.001 (4) | 0.024 (4) | 0.010 (4) |
H142 | 0.059 (5) | 0.052 (5) | 0.049 (4) | −0.015 (4) | 0.028 (4) | −0.012 (4) |
H143 | 0.064 (5) | 0.036 (5) | 0.056 (5) | −0.005 (4) | 0.027 (4) | 0.012 (4) |