PREFERRED METAL BINDING SITE OF ANILINE SUDESH KUMARI, BRAD SOHNLEIN, DILRUKSHI HEWAGE, and DONG-SHENG YANG University of Kentucky, Lexington, KY

BACKGROUND  High resolution UV of aniline with Ar, N 2  High resolution threshold spectroscopy of aniline and its van der Waals complexes  REMPI spectroscopy of aniline-water and aniline-methanol complexes  Theoretical study of aniline and its cation Sinclair W. E.; Pratt, D. W. J. Chem. Phys. 1996, 105, Song, X.; Yang, M.; Davidson E. R.; Reilly, J. P. J. Chem. Phys. 1993, 99, Zhang, X.; Smith, J. M.; Knee, J. L. J. Chem. Phys. 1992, 97, Piani, G.; Pasquini, M.; López-Tocón, I.; Pietraperzia, G.; Becucci, M.; Castellucci, E.; Chem. Phys. 2006, 330, 138. Wojciechowski, P.M.; Zierkiewicz, W.; Michalska, D.; Hobza P. J. Chem. Phys. 2003, 118,

BACKGROUND  IRMPD studies of Cr + -aniline and Cr + -aniline 2  Threshold CID studies of alkali metal cation-aniline complexes  Surface-enhanced Raman spectroscopy of adsorption of aniline on silver mirror Moore, D. T.; Oomens, J.; Eyler, J. R.; Heldon G. V.; Meijer, G.; Dunbar, R. C. J. Am. Chem. Soc. 2005, 127, Amunugama R.; Rodgers, M. T.; Int. J. Mass. Spectro. 2003, 227, 339. Qi, Y.; Hu, Y.; Xie, M.; Xing, D. Gu, H.; J. Raman Spectroc. 2010, 42, 1287.

Pulsed Valve and Rod Source Extraction Can MCP  -Metal Shielding Diffusion Pump HV GV TOF EXPERIMENTAL SETUP

PIE AND ZEKE SPECTRA OF Sc(C 6 H 5 NH 2 ) 40 psi 0-0

ZEKE SPECTRUM OF Sc(C 6 H 5 NH 2 ) psi

ZEKE SPECTRUM OF Sc(C 6 H 5 NH 2 ) psi Sohnlein, B. R.; Li, S.; Yang, D.-S. J. Chem. Phys. 2005, 123,

Sc, Ar Y, He/Ar mix La, He/Ar mix ZEKE SPECTRA OF Sc, Y, AND La(C 6 H 5 NH 2 ) 127, 151, 288, 354, 369, and 386 cm -1 69, 91, 128, 241, and 339 cm -1 22, 87, 110, 285, and 297 cm (375) (328) (295)

 Geometries and vibrational frequencies B3LYP G(d,p) {Sc, C, H, and N} SDD {Y and La}  Single point energies CCSD(T)//B3LYP  Intrinsic reaction coordinates calculations  Spectral simulations COMPUTATIONAL METHODS

StructureDescriptionE rel (cm -1 )PGState Neutral ground state0CsCs 1 A' Transition state (NH 2 inversion)273C 2v 1A11A1 Transition state (rotation of C-N bond)1934CsCs 1 A' Ionic ground state60772C 2v 2B12B1 STRUCTURES, RELATIVE ENERGIES (E rel ), POINT GROUPS (PG), AND ELECTRONIC STATES OF C 6 H 5 NH 2 BY B3LYP METHOD

POSSIBLE STRUCTURES  Structure of C 6 H 5 NH 2  Pi-structure two ways syn or anti  Binding to N of aniline/on C-N bond  Metal with NCC forming a four member ring  Metal with slight boat shaped aniline M ~ 3600 cm -1 higher

 True for every metal in the triad Ar carrier gas 1 A ' ← 2 A 3 A'' ← 4 A EXPERIMENT & SIMULATIONS OF Sc(C 6 H 5 NH 2 ) 3 A'' ← 2 A

Relative energy (cm -1 ) Intrinsic Reaction coordinates (IRC) calculations are done Ion only anti conformer ION NEUTRAL

Aniline-Ar NH 2 inversion Aniline NH 2 inversion An-Ar in ground state syn and anti conformations differs by 20 cm -1 Sinclair, W. E.; Pratt, D. W. J. Chem. Phys. 1996, 105, VIBRATIONALLY AVERAGED STRUCTURES

Sc-AnilineAnilineMode description ExpCalExp*Cal 127 (a) Out of plane; ring def.; little movement of Sc 151 (b) Out of plane; NH 2 wag; ring def. 288 (c) Out of plane; ring def.; significant Sc-aniline bend 354 (d) Out of plane; ring def.; Sc-aniline stretch 369 (e) Out of plane; NH 2 inversion; little Sc-aniline stretch 386 (f)385Sc-aniline stretch; little NH 2 wag In plane; CN rock, no movement of Sc Out of plane; NH twist In plane; ring def.; Sc almost fixed In plane; ring def. (some contribution from 577 of aniline as well) Out of plane; ring def.; NH 2 wag (179 vibrational mode in aniline) 5792 nd quanta of Out of plane; ring def.; CN and CH wag Out of plane; C-H bend (some 356 motion of aniline i.e ring def) CH and NH bond twist with p-CH bond fixed Out of plane; CH wag Out of plane; ring def.; CH bend CC and CN stretch In plane; NH 2 and CH rock Out of plane; CH bend In plane; ring stretch; little movement of NH Out of plane; CH bend In plane; ring stretch In plane CH scissor; ring stretch In plane; CH scissor; little NH 2 wag In plane; CC stretch; NH 2 rock *from previos studies

ZEKE SPECTRUM OF Sc(C 6 H 5 NH 2 )

CONCLUSIONS  Preferred binding site determined to be phenyl ring  Frank-Condon principle does not work Vibrationally averaged structures  Ground electronic states of the neutral and ion Neutral has syn and anti ( 2 A ) Ion has anti ( 1 A`)

Thank You!

StructureSc(C 6 H 5 NH 2 )Y(C 6 H 5 NH 2 )La(C 6 H 5 NH 2 ) E (rel) FreqE (rel) FreqE (rel) Freq Syn Anti Ion (Anti) TS Relative energies (E rel, cm -1 ) and M-L stretching frequencies by B3LYP method

WHY ANILINE? ComplexStructure Sc(C 6 H 5 X), Where X = H, CH 3, and F Sc(C 6 H 5 OH) Sc(C 6 H 5 CN) C 6 H 5 NH 2 Where metal is going to bind? Put reference

ComplexAIE Sc-C 6 H Sc-C 6 H 5 NH Y-C 6 H Y-C 6 H 5 NH La-C 6 H La-C 6 H 5 NH Table 3: Comparison between the experimental AIE (cm -1 ) of M-C 6 H 6 and M-C 6 H 5 NH 2 complexes where, M = Sc, Y, and La

Y-AnilineAnilineMode description ExpCalExpCal 69 (a) Out of plane; ring def.; little movement of Y 91 (b) 128 (c) Out of plane; NH 2 wag; ring def 163a+b 218b+c 241 (d) Out of plane; ring def.; significant movement of Y 339 (e)325Y-aniline stretch Out of plane; NH 2 inversiond+c In plane; CN rock, no movement of Ya+b+2c Out of plane; NH twistc+e In plane; ring def; Y almost fixeda+2d In plane; ring def (some contribution from 577 as well)b+c+e 565 Out of plane; ring def.; NH 2 wag.a+2c+d 590b+2c+d 650a+b+2d 6772 nd quanta of Out of plane; ring def. CH wagb+2c+e In plane; ring stretch; CH and NH rocka+2c+d+e rd quanta of 339

La-AnilineAnilineMode description ExpCalExpCal 22 (a) 87 (b) 110 (c)120La-NH 2 stretch Out of plane; ring def.; NH 2 twista+c nd quanta of c+a 285 (d) 297 (e)270La-aniline stretch Out of plane; aniline bending (some similarity to 179 mode of aniline)e+a In plane; CN rock, no movement of Lad+c Out of plane; NH 2 inversionc+e 5032c+d ring stretch (ring def.)2c+e Out of plane; ring def.; NH waga+2c+e In plane; ring def nd quanta of2d 5922 nd quanta of la-aniline stretch

Aniline bent (C s ) in ground state and planar in excited and ion state (C 2v ) In ground state dihedral angle b/w NH 2 and C 6 H 5 N plane is ~37° NH 2 wag. motion strongly anharmonic impossible to predict freq. with harmonic approx. inversion barrier a (~500 cm -1 ) thus described by double sym well another barrier exists little higher (~1200 cm -1 ) related to C-N bond rotation a James P. Reily observed three kinds of vibrational states in cation (total 36 normal modes) Background a Wang et al. 1993

BACKGROUND Why aniline? ComplexIE (cm -1 )Obs. Freq. (cm -1 )Mode descriptionStructure Sc(C 6 H 6 ) Sc-ligand stretch Sc(C 6 H 5 CH 3 ) Sc-ligand stretch Sc(C 6 H 5 OH)41477/ Sc-ligand stretch Sc(C 6 H 5 F) Sc-ligand stretch Sc(C 6 H 5 CN) Sc–C/N asymmetric stretch C/N move 716Sc–N stretch, N move 262Sc–C stretch Sc move C 6 H 5 NH 2 Where metal is going to bind?

Relative energy (cm -1 ) Intrinsic Reaction coordinates (IRC) calculations are done 2894 Ion only anti conformer ION NEUTRAL

Aniline-Ar NH 2 inversion Aniline NH 2 inversion An-Ar in ground state syn and anti conformations differs by 20 cm -1 Why anti str. favorable? - Attractive nature of lone pair - Repulsive nature of two N-H bonds Sinclair, W. E.; Pratt, D. W. J. Chem. Phys. 1996, 105, VIBRATIONALLY AVERAGED STRUCTURES