Hamburg_2011
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1 Engineering and Physical Sciences Research Council CP-FTMW Spectroscopy of Metal-containing Complexes Nicholas R. Walker, Susanna L. Stephens, Anthony C. Legon Max-Planck Advanced Study Group at the Center for Free Electron Laser Science 22nd September, 2011. Introduction 1) Microwave spectroscopy provides high precision in the determination of molecular geometries and hyperfine parameters. Can also provide insight into barriers to internal rotation and internal dynamics. 2) Recently completed construction of a chirped pulse Fourier transform microwave (CP-FTMW) spectrometer at the University of Bristol. The instrument benefits from recent advances in electronics that allow direct digitisation of waves at GHz frequencies. 3) Present results from complexes of CF3I that illustrate the capabilities of the spectrometer. 4) Show how the CP-FTMW spectrometer is being applied to the study of metal-containing complexes. 7 Animation : Prof. Wolfgang Jäger, Dept. of Chemistry, University of Alberta, Edmonton, AB, CANADA, T6G 2G2. CP-FTMW Spectrometer Pin diode limiter 300 W Power amplifier SPST switch Adjustable attenuator Low noise amplifier 7.0 - 18.5 GHz 7.0 - 18.5 GHz Power divider Mixer 12.2 GHz Low-pass band filter AWG (0.5-12 GHz) PDRO (19.00 GHz) 10 MHz reference frequency Mixer Oscilloscope (0-12 GHz) Multiple Free Induction Decay Acquisition per Valve Pulse Small percentage of OCS in 2 bar of helium. Faraday Discuss., 2011, 150, 284–285 Faraday Discuss., 2011, 150, 284–285 Crystal Engineering with Halogen Bonds E. Corradi, S. V. Meille, M. T. Messina, P. Metrangolo and G. Resnati, Tetrahedron Lett. 1999, 40, 7519-7523. V. Amico, S. V. Meille, E. Corradi, M. T. Messina and G. Resnati, J. Am. Chem. Soc. 1998, 120, 82618262. CF3I 13840 13860 13880 13900 Energy/MHz 8000 10000 12000 14000 Energy/MHz 16000 18000 CF3INH3 ?? CF3INH3 8000 10000 12000 14000 Energy/MHz 16000 18000 13840 13860 13880 Energy/MHz 13900 Internal rotation? C3v Symmetric top ? [1] G. T. Fraser, F. J. Lovas, R. D. Suenram, D. D. Nelson, Jr. and W. Klemperer, J. Chem. Phys. 1986, 84, 5983-5988. [2] G. Valerio, G. Raos, S. V. Meille, P. Metrangolo and G. Resnati, J. Phys. Chem. A, 2000, 104, 1617-1620. The Hamiltonian H R ( B0 DJΚ K 2 DJ m m 2 DJKm Km)( J ( J 1)) DJ J 2 ( J 1) 2 N Rcm I Exp. Simulation and fitting using PGOPHER (2010, version 7.0.103), a Program for Simulating Rotational Structure, C. M. Western, University of Bristol, http://pgopher.chm.bris.ac.uk. Sim. [80 kHz FWHM] 13850 13860 13870 Energy/MHz CF3I14NH3 Total (A and E) sim. E species sim. A species sim. 13850 13855 13860 13865 13870 13875 Energy/MHz Exp. CF3I14NH3 Sim. 10370 10380 Energy/MHz 10390 Exp. Sim. CF3I15NH3 10150 10160 10170 Energy/MHz CF3I CF3I14N(CH3)3 8000 10000 12000 14000 Energy/MHz 16000 18000 Exp. CF3I14N(CH3)3 A and E species sim. 8790 8800 8810 8820 Energy/MHz 8830 8840 Structure N I Rcm I bb NH3 NH3 CF3I CF3I I I I I 2 M S Rcm bb 1 cos 2 cc sin 2 bb 1 cos 2 aa sin 2 2 2 2 2 aa (N) implies = 20.5(12) for CF3INH3 and = 16.2(20) for CF3IN(CH3) 3.054 Å > rNI > 3.034 Å for CF3INH3 where 30>>0 and 8>>0 2.790 Å > rNI > 2.769 Å for CF3IN(CH3)3 where 30>>0 and 8>>0 E. Corradi, S. V. Meille, M. T. Messina, P. Metrangolo and G. Resnati, Tetrahedron Lett. 1999, 40, 7519-7523. rNI=2.84(3) Å. V. Amico, S. V. Meille, E. Corradi, M. T. Messina and G. Resnati, J. Am. Chem. Soc. 1998, 120, 82618262. rNI close to 2.80 Å. 3.054 Å > rNI > 3.034 Å for CF3INH3 where 30>>0 and 8>>0 2.790 Å > rNI > 2.769 Å for CF3IN(CH3)3 where 30>>0 and 8>>0 Correspondence with solid state H2SICF3 K=1 Spectrum assigned using a symmetric top Hamiltonian. K=0 K=2 H2OC6H6 and H2SC6H6 [1] E. Arunan et al. J. Chem. Phys., 2002, 117, 9766-9776. [2] S. Suzuki et al. Science, 1992, 257, 942-945. [3] H. S. Gutowsky et al. J. Chem. Phys., 1993, 99, 4883-4893. [4] H. Ram Prasad et al. J. Mol. Spectrosc. 2005, 232, 308-314. Exp. Sim. 11130 11140 11150 11160 Frequency / MHz 11170 H2O CF3Cl and H2OCF4 [5] W. Caminati, A. Maris, A. Dell’Erba and P. G. Favero, Angew. Chem. Int. Ed. 2006, 45, 6711 – 6714. [6] L. Evangelisti, G. Feng, P. Écija, E. J. Cocinero, F. Castaño and W. Caminati, Angew. Chem. Int. Ed., (in press). H2OICF3 Superposition of spectra assigned using symmetric and asymmetric top Hamiltonian’s, respectively. Total sim. Sym. Asym. Exp. . Exp. Sim. . Total sim. 10050 10100 10150 Energy/MHz 10200 10250 Laser ablation source Laser ablation source informed by the designs currently used by Duncan and co-workers, Gerry and co-workers, Ziurys and co-workers. OCAgI 109 AgI 107 AgI CF3I AgI 8000 10000 12000 14000 16000 Frequency/MHz 18000 OCAgI OC109AgI 109 AgI 107 OC107AgI AgI Exp. Sim. OCICF3 13200 13400 13600 13800 14000 Frequency / MHz 14200 14400 Conclusions • CP-FTMW spectroscopy has greatly accelerated the speed at which it is possible to measure and analyse rotational spectra. • In the first year of full operation, the spectra of NH3ICF3, N(CH3)3ICF3, H2OICF3, H2SICF3, OC ICF3, Kr ICF3 have been analysed and described in a series of papers. (Two papers in press with PCCP, one paper in press with JCP). • The spectra of OCAgI and H2SAgI have been measured and the molecular geometries have been determined. Further analysis and theoretical calculations are in progress. • Future applications in molecular dynamics and analytical chemistry seem possible. Acknowledgements University of Bristol Susanna Stephens Tony C. Legon Colin M. Western David P. Tew University of Virginia Brooks H. Pate Stephen T. Shipman University of Sheffield Michael Hippler University of Oxford Brian Howard Financial Support Engineering and Physical Sciences Research Council 1946 - First high resolution spectroscopic measurements using microwaves (B. Bleaney). 1950 1960 1970 3 1954 – Invention of the Maser (Gordon, Zeiger and Townes). 1968 – First polyatomic molecule identified in space is NH3. 1980 1981 – cavity FT-MW spectroscopy (Balle and Flygare). 1990 Explore intermolecular Pre-reactive complexes potentials. Hydrogen and van der Waals bonding. 2000 2002 – rotational spectra of OCS in He droplets Experimental 532 nm Lens Nozzle and Cu rod Ar/H2O/CCl4 Ar/H2O/CCl4 supersonic expansion Pump 6 Balle-Flygare FTMW Spectrometer 10 MHz Frequency Doubler 20 MHz Single Sideband modulator Adjustable frequency 10 MHz e - 20 MHz (6 ≤ e ≥ 18 GHz) -20 MHz SPDT MW Signal Attenuators generator switch e - 20 MHz Image rejection mixer m (m - e) +20 MHz =Δ +20 MHz 10 MHz Low Band Pass Filter Δ +20 MHz MW 20 MHz Signal Generator RF Mixer +Δ Pre-amp Digitiser and computer SPDT switch Low Noise Amplifier e e MW Amplifier SPDT switch Fabry-Perot Resonator Parallel Propagation m 350 mm diameter 840 mm curvature radius ~700 mm distance aluminum 510 mm 180 mm 394 mm CF3I 8000 10000 12000 14000 Energy/MHz 16000 18000 But what’s this stuff ???? 3 hours of averaging, CF3I, CO and Ar gas sample Normalized Intensity / MHz 0.02 0.01 0.00 10680 10690 10700 10710 10720 Energy/MHz 10730 10740 A new complex of CF3I and CO 10750 CF3I 8000 10000 12000 14000 Energy/MHz 16000 18000 But what’s this stuff ???? 6 hours of averaging, CF3I, N(CH3)3 and Ar gas sample Normalized Intensity / MHz 0.015 0.010 0.005 0.000 9660 9670 9680 9690 9700 Energy/MHz 9710 9720 A new complex of CF3I and N(CH3)3 9730 C2H4ICF3 Exp. Total sim. Prof. Brian Howard, University of Oxford Exp. Total sim. Asym. Sym. 11280 11300 11320 11340 11360 Energy/MHz 11380 H2SAgI H2SICF3 109 AgI 107 AgI H2S 107AgI . H2S 109AgI 13300 13400 13500 13600 Frequency / MHz 13700 39.1º 1000 800 3 V(φ)/cm-1 600 2 400 1 V=0 200 0 -80 -60 -40 -20 0 20 40 60 80 φ/deg “Identification and molecular geometry of a weakly bound dimer (H2O,HCl) in the gas phase by rotational spectroscopy” A. C. Legon and L. C. Willoughby, Chem. Phys. Letters, 95, 449-52, (1983). 4000 3000 2000 V(φ)/cm-1 5 3 1000 4 2 1 V=0 0 -120 -90 -60 -30 0 φ/deg. 30 60 90 120 Nuclear Quadrupole Coupling Constants aa (M) / MHz aa (Cl) / MHz M=Cu M=Cu MCl ArMCl KrMCl H2OMCl H3NMCl H2SMCl OCMCl H4C2MCl 16.2 33.2 36.5 50.3 61.8 70.8 63.8 32.1 28.0 27.3 25.5 23.0 21.5 21.0 NaCld ArNaCld M=Ag 36.4 34.5 33.8 32.3 29.8 29.4 28.1 27.9 / MHz 5.7 5.8 Ionicity, ic M=Cu M=Ag 0.71 0.67 0.74 0.69 0.75 0.69 0.77 0.71 0.73 0.79 0.73 0.80 0.74 0.81 0.75 Ionicity, ic 0.95 0.95 • Determination of the molecular geometry of each of the above complexes completed (where possible from isotopic substitution). • Nuclear quadrupole coupling constants provide measure of charge redistribution after formation of the complex. Theory cc-pVTZa cc-pVQZb r0 rAgCl / Å 2.280 2.272 2.273(6) cc-pVTZ cc-pVQZ r0 rAgCl / Å 2.2783 2.2714 2.26333(6) cc-pVTZ cc-pVQZ r0 rAgCl / Å 2.2835 2.2777 2.26882(13) cc-pVTZ cc-pVQZ r0 rAgCl / Å 2.2837 2.2771 2.2724(8) H2OAgCl rAgO / Å 2.280 2.209 2.198(10) H3NAgCl rAgN / Å 2.1619 2.1530 2.15444(6) H2SAgCl rAgS / Å 2.4049 2.3875 2.38384(12) H4C2AgCl rAgX / Å 2.1975 2.1945 2.1719(9) /˚ 45.0 43.7 37.4(16) AgNH 111.87 111.68 113.48(2) /˚ 76.2 76.2 78.052(6) CCH 121.46 121.46 123.02(6) Dr. David Tew, University of Bristol • CCSD(T) calculations. • cc-pVTZ basis sets for H, O. • cc-pV(T+d)Z basis set for Cl. • cc-pVTZ-PP for Ag. Publications on BMX Complexes H3N...AgCl, V.A. Mikhailov et al., Chem. Phys. Lett. 499, 16-20 (2010) H2O...CuCl and H2O...AgCl ; V.A. Mikhailov et al., J. Chem. Phys., 134, 134305 (2011) H2O...AgF, S.L. Stephens et al., J. Mol. Spectrosc. 267, 163-168 (2011) H2S...CuCl and H2S...AgCl; N.R. Walker et al., J. Chem. Phys. 135, 014307 (2011) C2H4...Ag-Cl; S.L. Stephens et al., J. Chem. Phys. 135, 024315 (2011) Endo and co-workers
