Lena F. Elmuti, Daniel A. Obenchain, Don L. Jurkowski, Cori L. Christenholz, Amelia J. Sanders, Rebecca A. Peebles, Sean A. Peebles Department of Chemistry, Eastern Illinois University, 600 Lincoln Avenue, Charleston, IL Amanda L. Steber, Justin L. Neill, Brooks H. Pate Department of Chemistry, University of Virginia, McCormick Rd., PO Box , Charlottesville, VA 22904

Recent work in C-H···π Interactions ? ? CHClF 2 ···HCCH a CH 2 F 2 ···HCCH CH 2 ClF···HCCH a Elmuti, L. F.; Peebles, R. A.; Peebles, S. A.; Steber, A. L.; Neill, J. L.; Pate, B. H. J. Phys. Chem. Chem. Phys. 2011, DOI /c1cp20684b 2 Cl F 3.061(38) Å 2.730(6) Å Cl F

CH 2 ClF··· HCCH a b initio Structures  MP2/ G(2d,2p) level A /MHz5120 B /MHz1625 C /MHz1243 E ZPE /cm -1 0 A /MHz9652 B /MHz1204 C /MHz1078 E ZPE /cm a b Chlorine out structure Chlorine in structure b a 3

CH 2 ClF ··· HCCH Spectrum Measurement  CP-FTMW (University of Virginia) a GHz 350,000 averages 0.75% CH 2 ClF/ 1.0% HCCH diluted in He, P= 2 atm Fit using AABS package from Kisiel b and SPFIT/SPCAT software c  Less intense transitions and 13 C isotopologues measured on the Balle-Flygare cavity FTMW (Eastern Illinois University) d, e 1.0% CH 2 ClF/ 1.0% HCCH diluted in He/Ne (17.5%/82.5%) P= atm a Brown, G. G.; Dian, B. C.; Douglass, K. O.; Geyer, S. M.; Shipman, S. T.; Pate, B. H. Rev. Sci. Instrum. 2008, 79, b Kisiel, Z.; Pszczolkowski, L.; Medvedev I.R.; Winnewisser, M.; De Lucia, F. C.; Herbst, C. E. J. Mol. Spec. 2005, 233, c Pickett, H. M. J. Mol. Spec. 1991, 148, 371 d Balle, T. J.; Flygare, W. H. Rev. Sci. Instrum. 1981, 52, 33 e Newby, J. J.; Serafin, M. M.; Peebles, R. A.; Peebles, S. A. Phys. Chem. Chem. Phys. 2005, 7, 487 4

CH 2 ClF 1 11 ← /2 ← 7/2 S/N ≈ 2800 CH 2 ClF···HCCH 3 03 ← /2 ←7/2 S/N ≈ 250 CH 2 35 ClF···HCCH CH 2 37 ClF···HCCH CH 2 ClF···HCCH Spectrum 5

CH 2 ClF· · ·HCCH Constants Ab initio Chlorine in CH 2 35 ClF··· H 12 C 12 CH CH 2 37 ClF··· H 12 C 12 CH CH 2 35 ClF··· H 13 C 13 CH CH 2 37 ClF··· H 13 C 13 CH A / MHz (14) (12) (21) (24) B / MHz (10) (15) (11) (11) C / MHz (7) (10) (7) (8) χ aa / MHz (5)22.270(7)28.362(8)22.096(8) χ bb / MHz–60.13–65.618(13)–51.496(22)–65.474(21)–51.337(20) χ cc / MHz (8)29.226(14)37.112(13)29.240(12) χ ab / MHz– – – – NaNa – Δν rms / kHz b – P cc / uÅ (4)1.7478(15)1.7461(5)1.7426(5) a number of fitted transitions b Δν rms =√(∑(ν obs -ν calc ) 2 /N) c Blanco, S.; Lesarri. A.; López, J. C.; Alonso, J. L.; Guarnieri, A. J. Mol. Spec. 1995, 174, 397 P cc (CH 2 ClF) = (1) uÅ 2 c 6

CH 2 ClF···HCCH Structure Inertial Fit “Best” a Ab initio Chlorine in R |||…C / Å 3.605(4)3.476 θ C–|||…C / ° 73.9(9)73.6 θ |||…C–Cl / ° 91.87(27)94.3 R Cl…H / Å 3.207(22)3.138 R |||…H / Å 3.236(6)3.101 θ C–H…||| / ° 101.0(1)101.2 θ C–H…Cl / ° 109.0(1.0) (22) Å R H…p = 3.236(6) Å q C-H…p = 101.0(1)° 91.87(27)° 73.9(9)° 3.605(4) Å 109.0(10)° 85.2(22)° Cl F a average of the structures produced by fitting (I a, I b, I c ), (I a, I b ), (I a, I c ), and (I b, I c ) in STRFITQ b Δν rms =√(∑(ν obs -ν calc ) 2 /N) 7

CH 2 F 2 ···HCCH Predictions A /MHz11211 B /MHz1703 C /MHz1493 E ZPE /cm -1 0 A /MHz8121 B /MHz2067 C /MHz1838 E ZPE /cm A /MHz10588 B /MHz1498 C /MHz1323 E ZPE /cm  MP2/ G(2d,2p) level 8 1 imaginary frequency

CH 2 F 2 ···HCCH Spectrum Measurement CP-FTMW at Eastern Illinois University 1.5% CH 2 F 2 / 1.5% HCCH in 5 bar He/Ne, 1.6 atm backing pressure 480 MHz Chirp, 1000 averages GHz Balle-Flygare FTMW Spectrometer at Eastern Illinois University a a Obenchain, D.A.; Elliott, A.A.; Steber, A.L.; Peebles, R.A.; Peebles, S.A. Wurrey, C.J.; Guirgis, G.A. J. Mol. Spec. 2010, 261,

CH 2 F 2 ···HCCH Spectrum CH 2 F 2 ···HCCH CH 2 F 2 ···H 2 O a (CH 2 F 2 ) 3 b (CH 2 F 2 ) 2 c a Caminati,W.; Melendra, S; Rossi, I.; Favero, P. G. J. Am. Chem. Soc. 1999, 121, b Blanco, S.; Melandri, S.; Ottaviani, P. Caminati, W. J. Am. Chem. Soc. 2007, 129 (9), 2700 c Blanco, S.; López, J. C.; Lesarri, A.; Alonso, J. L. J. Mol. Struct. 2002, 612, avg scan 1.5% CH 2 F 2 1.5% HCCH in 5 bar He/Ne

 From the original 1000 average scan  Only a-types were visible in the original scan  Potential b-type transitions were found in a 2000 average scan with a smaller chirp ( MHz) 13 CH 2 F 2 ···HCCH Isotopologue 12 CH 2 F 2 ···H 12 C 12 CH CH 2 F 2 ···H 12 C 12 CH

CH 2 F 2 ···HCCH Constants Parameter Ab initio MP2/ G(2d,2p) CH 2 F 2 ···HCCH 13 CH 2 F 2 ···HCCHCH 2 F 2 ···H 13 C 13 CH A /MHz (18) (24) (20) B /MHz (5) (8) (5) C /MHz (5) (8) (5) Δν rms /kHz a NbNb P aa /uÅ (14) (25) (16) P bb /uÅ (14) (25) (16) P cc /uÅ (14) (25)1.6724(16) P cc (CH 2 F 2 ) = (1) uÅ 2 c a Δν rms =√(∑(ν obs -ν calc ) 2 /N) b number of fitted transitions c Hirota, E.; Tanaka, T.; Sakakibara, A.; Ohashi, Y.; Morino, Y. J. Mol. Spec. 1970, 34,

CH 2 F 2 ···HCCH Stark Effects Transition10 5 x (Δν/E 2 ) obs.10 5 x (Δν/E 2 ) calc ←1 01 |M|= ←1 01 |M|= ←2 02 |M|= ←2 02 |M|= ←2 02 |M|= ←0 00 |M|= ←2 12 |M|= This StudyAb initio μ a /D1.511(3)1.68 μ b /D1.2246(19)1.29 μ total /D (26)2.12 c a b 13 μ total (CH 2 F 2 ) = 1.97(2) D a a Lide, D. R. Jr. J. Am. Chem. Soc. 1952, 74 (14) 3548

Inertial Fit “Best” a Ab initio Structure R |||···C /Å 3.625(9)3.51 θ C-|||···C /° 70.2(28)66.5 θ |||···C-F /° 80.0(8)83.7 R F···H /Å2.84(6)2.68 R H···||| /Å3.363(14)3.22 R cm /Å4.033(1)3.937 θ C-H···||| /°94.9(3)96.2 θ C-H···F /°105(3)111 θ C-F···H /°104.5(13)99.7 CH 2 F 2 ···HCCH Structure 3.625(9) Å R H···||| = 3.363(14) Å θ C-H…||| = 94.9(3)° 70.2(28)° 80.0(8)° 104.5(13)° 105(3)° 2.84(6) Å a /Åb /Å Substitution (11) (2) Inertial fit (I a, I c ) Ab initio structure a average of the structures produced by fitting (I a, I b, I c ), (I a, I b ), (I a, I c ), and (I b,I c ) in STRFITQ 14

HCCH complex k s /N m -1 E b / kJ mol -1 CH 2 F (3)3.88(6) CH 2 ClF3.46(2)4.75(4) CHClF 2 a 3.7(5) [3.7(5)] b 4.9(5) [5.0(5)] b CHBrF 2 c 1.82(1)2.46(3) Force Constants and Binding Energies 15 a Elmuti, L. F.; Peebles, R. A.; Peebles, S. A.; Steber, A. L.; Neill, J. L.; Pate, B. H. Phys. Chem. Chem. Phys DOI /c1cp20684b b Strucure refit using a refined CHClF 2 monomer structure. Vincent, M. A.; Hillier, I. H. Phys. Chem. Chem. Phys. 2011, 13, 4388 c Obenchain D. A.; Bills, B. J.; Christenholz, C. L.; Peebles, R. A.; Peebles, S. A.; Neill, J. L.; Pate, B. H. Manuscript in preparation

C-H···π Interactions CH 2 F 2 ···HCCHCH 2 ClF···HCCHCHClF 2 ···HCCH a CHBrF 2 ···HCCH R |||-C /Å3.625(9)3.605(4) 3.710(4) [3.676] 3.683(7) R |||-H /Å3.363(14)3.236(1) 2.730(6) [2.655] 2.670(8) θ |||···C-X /˚80.0(8)91.87(27) 88.0(5) [87.7] 91.71(94) R C-C / Å3.468(37)3.487(10) 3.563(16) [3.500] 3.540(14) 16 a Strucure refit using a refined CHClF 2 monomer structure. Vincent, M. A.; Hillier, I. H. Phys. Chem. Chem. Phys. 2011, 13, 4388

 Distributed Multipole Analysis Up to quadrupole terms considered  GDMA 2.2 Anthony Stone a  MIN16 Buckingham-Fowler model b,c PROSPE website d,e Electrostatic Interactions 17 Lowest Energy Highest Energy Buckingham- Fowler Model Ab initio MP2/ G(2d,2p) a Stone, A. J. J. Chem Theory Comp. 2005, 1, 1128 b Buckingham A. D.; Fowler P. W. J.Chem.Phys. 1983, 79, 6426 c Buckingham A. D.; Fowler P. W. Can.J.Chem. 1985, 63, 2018 d Kisiel Z.; Fowler, P. W.; Legon A.C. J. Chem. Phys. 1990, 93, 3054 e Kisiel Z. MIN16, PROSPE. E ZPE = 0 cm -1 E ZPE = 34 cm -1 E ZPE = 64 cm -1 E ZPE = 165 cm -1 1 imaginary frequency

Electrostatic Interactions Lowest Energy Highest Energy Buckingham- Fowler Model Ab initio MP2/ G(2d,2p) 18 E ZPE = 0 cm -1 E ZPE = 13 cm -1 E ZPE = 26 cm -1 E ZPE = 231 cm -1

Conclusions  Assigned the spectrum of CH 2 ClF···HCCH (4 isotopologues) and CH 2 F 2 ···HCCH (3 isotopologues) Structure fits ○ Similar R C-C distance for analog HCCH complexes Dipole moments of CH 2 F 2 ···HCCH ○ Agree with ab initio to within expected deviation ○ No enhancement of the dipole moment from the measured monomer value Force constants and binding energies ○ Appears that the chlorine containing halomethanes are more strongly bound to acetylene than the other halomethanes studied thus far 19

Conclusions  Intermolecular Interactions Electrostatic model can be used to predict possible asymmetric structures ○ Preference of the lowest energy structure cannot be determined by only an electrostatic model ○ Orient a  Additional studies are still needed to reliably determine the types of intermolecular interactions that are influencing the structures of these complexes 20 a Stone, A. J.; Dullweber, A.; Engkvist, O.; Fraschini, E.; Hodges, M. P.; Meredith, A. W.; Nutt, D. R.; Popelier, P. L. A.; Wales, D. J. 2002, ‘Orient: a program for studying interactions between molecules, version 4.5,’ University of Cambridge, Enquiries to A. J. Stone,

Current Projects 21  CH 2 ClF Vinyl Fluoride CH 2 =CH 2 CO 2  CH 2 F 2

Support  NSF Research at Undergraduate Institutions CHE  Professor Kuczkowski for the H 13 C 13 CH sample 22

I a, I b, I c a I a, I b a I a, I c a I b, I c a “Best” b Ab initio Structure I R |||…C / Å 3.605(3)3.608(3)3.600(3)3.606(3) 3.605(4)3.476 θ C–|||…C / ° 74.10(5)74.93(5)73.43(5)73.47(5) 73.9(9)73.6 θ |||…C–Cl / ° 91.82(21)91.71(21)92.19(22)91.72(21) 91.87(27)94.3 R Cl…H / Å c 3.210(2)3.232(2)3.198(2)3.190(2) 3.207(22)3.138 R |||…H / Å c 3.237(16)3.240(16)3.229(18)3.238(16) 3.236(6)3.101 θ C–H…||| / ° c 100.9(7) 101.1(7)100.9(7) 101.0(1)101.2 θ C–H…Cl / ° c 108.8(1)107.8(1)109.6(1)109.5(1) 109.0(1.0)110.1 rms / u Å 2 d –– CH 2 ClF···HCCH Structure 23

CH 2 35 ClF–H 12 C 12 CHCH 2 37 ClF–H 12 C 12 CHCH 2 35 ClF–H 13 C 13 CHCH 2 37 ClF–H 13 C 13 CHAb initio Chlorine in A / MHz (14) (12) (21) (24) 5120 B / MHz (10) (15) (11) (11) 1625 C / MHz (7) (10) (7) (8) 1243  J / kHz 3.308(12)3.158(34)3.287(19)3.163(18) –  JK / kHz 14.03(8)14.63(12)11.95(11)12.66(14) –  K / kHz –402(14)–439(46)–598(22)–583(24) –  J / kHz 0.830(15)0.874(25)0.929(15)0.784(17) –  aa / MHz (5)22.270(7)28.362(8)22.096(8)  bb / MHz –65.618(13)–51.496(22)–65.474(21)–51.337(20) –60.13  cc / MHz (8)29.226(14)37.112(13)29.240(12)  ab / MHz – – – – – P cc / u Å (4)1.7478(15)1.7461(5)1.7426(5) N cN c –  rms / kHz – CH 2 ClF···HCCH Constants 24

CH 2 F 2 ···HCCH Structure I a, I b, I c I a, I b I a, I c I b, I c “Best” Ab initio Structure R |||···C /Å 3.625(2)3.625(7)3.617(12)3.631(11)3.625(9)3.51 θ C-|||···C /° 70.5(38)70.5(36)66(6)74(7)70.2(28)66.5 θ |||···C-F /° 79.9(11) 81.3(19)79.1(16)80.0(8)83.7 R F···H /Å 2.84(11)2.84(1)2.75(16)2.92(19)2.84(6)2.68 R H···||| /Å 3.365(4)3.364(15)3.346(19)3.377(18)3.363(14)3.22 R cm /Å 4.033(18)4.033(9)4.033(17)4.033(15)4.033(1)3.937 θ C-H···||| /° 94.9(5) 95.4(8)94.5(7)94.9(3)96.2 θ C-H···F /° 105(5) 110(7)101(7)105(3)111 θ C-F···H /° 104.7(14)104.7(12)102.4(24)106.1(20)104.5(13)99.7 Rms/ uÅ (7) Å R H···||| = 3.63(11) Å θ C-H…||| = 94.9(3)° 70.2(28)° 80.0(8)° 104.5(13)° 105(3)° 2.84(6) Å 25

Instruments  CH 2 ClF···HCCH CP-FTMW at the University of Virginia  CH 2 F 2 ···HCCH CP-FTMW at Eastern Illinois University  Balle-Flygare FTMW at Eastern Illinois University Used to measure transitions of both species Weak components of parent species and isotopologues 26

CH 2 F 2 ···HCCH CH2F2CHF3 CH2ClFCHClF2CHBrF2 Acetylene k s /N m (3)--3.46(2)3.7(5)1.82(1) E b /kJ mol (6)--4.75(4)4.9(5)2.46(3) Carbonyl Sulfide k s /N m (1) 1.2(1) 3.25(7)--- E b /kJ mol (1) 1.6(1) 3.5(1)--- Carbon Dioxide k s /N m (2)---- E b /kJ mol (4)---- Water k s /N m (2)- E b /kJ mol (2)- 27

CH 2 F 2 ···HCCH Constants Parameter ab initio MP2/( G(2d,2p)) CH 2 F 2 ···HCCH 13 CH 2 F 2 ···HCCHCH 2 F 2 ···H 13 C 13 CH A /MHz (18) (24) (20) B /MHz (5) (8) (5) C /MHz (5) (8) (5) Δ J /kHz- 5.22(12) 5.216(26) a 4.819(12) Δ JK /kHz (8) a (8) δ J /kHz (32) a 0.774(3) δ K /kHz- 20.2(23) 20.2 a 2.02(24) Δν rms /kHz N c P aa /uÅ (14) (25) (16) P bb /uÅ (14) (25) (16) P cc /uÅ (14) (25) (16) P cc (CH2F2) = 1.651(1) uÅ 2 28

Electrostatic Interactions Relative energy Dipole- Quadrapole Quadrapole- Quadrapole

Electrostatic Interactions Lowest Energy Highest Energy Buckingham- Fowler Model Ab initio MP2/ G(2d,2p) 30 E ZPE = 0 cm -1 E ZPE = 13 cm -1 E ZPE = 26 cm -1