Lomonosov Moscow State University Faculty of Chemistry Structures and dynamics of free molecules: a tale of two nitrocompounds Denis Tikhonov 25-08-2017 53rd Symposium on Theoretical Chemistry The Great Quest for Truth 1 ! |Quantum chemistry Gas{z Electron Diffraction} # Equilibrium geometry Mata R., Suhm M. // Angew. Chem. Int. Ed., 56 (2017), DOI: 10.1002/anie.201611308 Tetranitromethane (TNM) 2 • Spectroscopy: S4 symmetry 3 • Quantum chemistry: S4 symmetry 3 • Gas Electron Diffraction: – 1939 3 – 1970-s 3 – 2016 7) Stosick A. et al. // JACS, 61, pp. 1127–1130 (1939) Lindenmeyer P. et al. // J. Chem. Phys., 21, pp. 408–414 (1953) Sadova N. et al. // J. Struct. Chem., 15, pp. 593–595 (1974) Sadova N. et al. // J. Mol. Struct., 31, pp. 399–402 (1976) Internal dynamics of TNM 3 4 internal rotations of NO2 groups Dynamic model in GED 4 LAM SAM, thus: vib(qLAM; qSAM) LAM(qLAM) ¡ SAM(qSAMjqLAM) (adiabatic separation of LAMa и SAMb) Usually hmax max = LAM T D;LAM k exp therefore: V (q ) (q ) / exp LAM LAM LAM kT a - LAM = large-amplitude motions b - SAM = small-amplitude motions T˙ Cur`e of Dimen`ionality in GED 5 1D dynamic models: boooooring... since 1950-s 2D dynamic models since 2000, less then dosen 3D dynamic models currently only one case aviliable Morino Y. et al. // J. Chem. Phys., 28, 185–197 (1958) Tsuji T. et al. // J. Mol. Struct., 554, 203–210 (2000) Kovtun M. et al. // J. Phys. Chem. A, 119, 1657–1665 (2015) Khaikin L. et al. // Struct. Chem., 26, 1651–1687 (2015) TNM vs. TNB 6 TNM vs. TNB 7 1,3,5-trinitrobenzene Tetranitromethane PES scan increment = 10 N 363 5 ¡ 102 N 364 4 ¡ 103 uniq > jG96j uniq > jG384j Let’s roll the dice! 8 Metropolis Monte-Carlo PES scan ! 4D GED dynamic model Vishnevskiy Yu. et al. // Angew. Chem. Int. Ed., 56, pp. 9619–9623 (2017) Finding structure of TNM 9 Vishnevskiy Yu. et al. // Angew. Chem. Int. Ed., 56, pp. 9619–9623 (2017) Nitroxoline (NXN) 10 Conformational properties of NO2-group: to be or not to be planar or not planar? \CCNO (') NXN in DFT (PBE0) 11 NXN @ true ab initio 12 GED of NXN 13 V2 V4 V6 Vexp(') = V0 + (1 cos(2')) + (1 cos(4')) + (1 cos(6')) 2 2 2 The twist of NO2-group in NXN 14 Equilibrium value for \CCNO ('): Experimental: GED 8(3) Double-: CCSD/cc-pVDZ 24 DFTa/cc-pVDZ0 MP2(fc)/cc-pVDZ 27 Triple-: B3LYP/cc-pVTZ 11 ri-MP2(full)/cc-pVTZ 26 PBE0/cc-pVTZ8 PBE/cc-pVTZ4 MP2(full)/cc-pwCVTZ 13 TPSS/cc-pVTZ0 Quadriple-: PBE0/cc-pVQZ8 PBE0-D3/cc-pVQZ9 a – DFT = B3LYP, PBE, PBE0, TPSS Conclusions 15 GED says, that: • now the equilibrium structure of tetranitromethane is found and it is S4 • nitroxoline is not planar and DFT gives better results, then MP2 and DLPNO-CCSD[T] Acknowlegments 17 Tetranitromethane team: • Dr. Yu. Vishnevskiy • J. Schwabedissen • Prof. N. Mitzel Nitroxolin team: • Dr. D. Sharapa • A. Otlyotov • Dr. A. Rykov Thank You for the Attention! Gas Electron Diffraction (GED) 20 • Beginning: Mark and Wierl in Germany (1930) • Some people: – Peter Debye (NP @ 1936) – Linus Pauling (NP @ 1954) – Odd Hassel (NP @ 1969) • Variants of GED: – Structural GED (geometry) – Small-angle GED (electron density) http://molwiki.org/ – TRED wiki/BielefeldGED: (transition states) Equipment Structural GED worldwide 21 Currently: GED: basics 22 # 4 s = sin 2 The case of semi-rigid molecules 23 X l2 s2 ¡ ( ) ( ) ij ¡ s Imol s gij s 3 sM (s) = = e 2 sin sra;ij s ij ; Iat(s) ra;ij i;j 6=i D E 1 1 l2 ra = hri ; r |{z} re rg 1 ¡ l2 = hr 2i hri2 ; = hr 3i 3hrihr 2i + 2hri3 ; 6 Vibrational effects in GED 24 CS2: \g (SCS) 173 @ 288 K r (CS)h 2i r (S ¡¡¡ S) 2r (CS) e ; = (SCS) g g 4 \ “Bastiansen – Morino Shrinkage Effect” Tikhonov D. et al., PCCP, 2016, 18, 28325–28338 NXN in DFT (PBE) 25 NXN in DFT (B3LYP) 26 Let’s roll the dice! 27 .