1. + MILLIMETER-WAVE SPECTROSCOPY OF ETHYLMERCURY HYDRIDE Manuel Goubet, Roman A. Motiyenko, Laurent Margulès Laboratoire PhLAM, Université Lille 1 Jean-Claude Guillemins Sciences Chimiques de Rennes - ENSCR

2. + Chemistry background Synthesis of organomercury compounds: Guillemin, J.-C.; Bellec, N.; Kiz-Szetsi, S.; Nyulaszi, L.; Veszpremi, T. Inorg. Chem. 1996, 35, 6586 − 6591. Craig, P. J.; Garraud, H.; Laurie, S. H.; Mennie, D.; Stojak, G. H. J. Organomet. Chem. 1994, 468, 7 − 11. Extensive spectroscopic and ab initio study of gaseous HgH 2 and HgD 2 : Shayesteh, A.; Yu, S.; Bernath, P. F. J. Phys. Chem. A 2005, 109, 10280 − 10286.

3. + Ab initio structure of C 2 H 5 HgH Method: MP2(full) Basis sets: Hg - small core pseudo-potential basis set: cc-pVTZ-PP, accounting for relativistic effects C - cc-pCVTZ with extra core/valence functions H - standard cc-pVTZ Geometry optimization using « tight » convergence option 207.8 pm 161.5 pm 153.1 pm 113.5° A = 29464.95 MHz B = 2817.15 MHz C = 2654.66 MHz μ a = 0.43 D; μ b = 0.13 D

4. + The Lille fast scan spectrometer BWO HV Power Supply F/32 + IF Amplifier Absorbing cell DDS 8.7 – 11.8 MHz SR7270 DSP Lock-in amplifier Bolometer RS-232 Synthesizer Agilent E8257D 8 – 16.5 GHz PLL, IF=8.7 – 11.8 MHz Amplifier RS-232 Internal bus Microcontroller ADuC 842 Ethernet fast frequency switching up to 20 μs/point frequency range in this study: 120 – 180 GHz Frequency synthesizer Absorbing cell Bolometer to diffusion + rotary pump Sample at 250 K At room temperature

5. + The spectrum 5.34 GHz ≈ B+C 202 Hg 201 Hg 200 Hg 199 Hg 198 Hg 204 Hg ν 23 = 1 excited state ω = 199 cm -1 ab initio: B+C = 5.45 GHZ 201 Hg I = 3/2 ν 22 = 1 excited state ω = 233 cm -1 V 3 = 1100 cm -1 CH 3 top internal rotation ? 17 GHz spectrum recorded in ≈20 min (0.024 MHz frequency step)

6. + Calculation of nuclear quadrupole tensor pseudo-potential should not be used however high-level all electrons calculations of the electric field gradient for an atom like Hg might become unreasonably time consuming the solution is to perform low level field gradient calculations (B1LYP/6-311G(df,p)) based on the geometry from high level calculations (see W.C. Bailey web- page at http://nqcc.wcbailey.net/)http://nqcc.wcbailey.net/ F=? ? ? ?

7. + Calculation of nuclear quadrupole tensor Calculations have been made at the the HF, B1LYP and B3LYP levels of theory Basis sets: Hg - all electrons ANO-RCC C and H – cc-pVDZ, 6-311G(df,p), cc-pVTZ and ANO-RCC For the consistency of the basis set over the molecule, the initial ANO basis was reduced to a double- or triple-zeta polarization according to the set used for H and C The two-electrons integrals were calculated using the second order Douglas-Kroll-Hess (DKH) Hamiltonian to take into account the relativistic effect The input geometry was the atomic Cartesian coordinates calculated at the MP2/cc-pVTZ-PP in the principal inertial axis orientation

8. + Calculation of nuclear quadrupole tensor: the results The agreement is improving faster by increasing the level of the method than the quality of the basis set If one has to compromise between accuracy and calculations time, the best choice would be a combination of a high level method and a small basis set χ aa χ bb HFB1LYPB3LYP Experiment cc-pVDZ (126) -1962 786 -1545 617 -1517 606 -1169.50(67) 473.33(61) 6-311G(df,p) (154) -1956 784 -1532 612 -1503 600 ANO-DZP (180) -1953 782 -1513 603 -1481 590 cc-pVTZ (237) -1919 778 -1467 585 -1435 572 ANO-TZP (291) -1942 778 -1415 562 -1376 546 63/2 – 61/2 57/2 – 55/2 61/2 – 59/2 59/2 – 57/2

9. + Calculation of nuclear quadrupole tensor: the results The angle between principal axis a and internuclear axis z containing quadrupolar atom (Legon, A. C. Faraday Discuss. 1994, 97, 19): χ ab can be estimated from the diagonal components in the assumption that the angular oscillation of the subunit containing the quadrupolar nucleus is two-dimensionally isotropic in the ab plane: Estimation: χ ab = 644.78 MHz and α az = 19.1° From ab initio calculations: α az = 19.6°

10. + Rotational spectroscopy: the results 202 Hg 200 Hg 199 Hg 201 Hg 198 Hg 204 Hg A /MHz29302.2001(35) 29464.946 29302.823(13)29303.129(11)29302.57(19)29303.509(44)29301.593(56) B /MHz2750.73634(10) 2817.149 2753.73409(19)2755.25383(17)2752.22888(73)2756.79080(44)2747.79563(50) C /MHz2593.295144(97) 2654.657 2595.96453(19)2597.31756(17)2594.62014(57)2598.68407(43)2590.67525(49) Δ J /kHz1.349427(53) 1.372 1.352251(62)1.353555(61)1.35144(20)1.355191(96)1.34668(11) Δ JK /kHz-28.73258(74) -29.288 -28.76191(78)-28.77643(82)-28.7520(23)-28.7924(11)-28.7069(15) Δ K /kHz514.23(20) 496.021 513.07(94)513.00(57)514.23516(16)514.23 δ J /kHz0.148784(10) 0.154 0.149193(44)0.149477(45)0.14952(16)0.149911(88)0.14848(12) δ K /kHz6.1780(76) 6.127 6.241(28)6.200(32)6.64(10)6.392(65)6.270(62) H KJ /Hz -2.0210(36)-2.0265(38)-2.0346(44)-1.996(11)-2.0342(56)-2.0291(99) L KKJ /mHz 0.1296(43)0.1334(48)0.1467(60)-0.1419(76)0.143(16) N lines561537483559449395 J max ; K max 52; 2651; 2643; 2434; 1646; 2534; 22 σ /MHz0.0240.0230.0190.0410.0270.026

11. +