CH 33 NAg I and H 3 NAg

(CH 3)3 N···Ag. I and H 3 N···Ag. I Studied by Broadband Rotational Spectroscopy and ab initio Calculations Dror M. Bittner, Daniel P. Zaleski, Susanna L. Stephens, Nicholas R. Walker, Anthony C. Legon

Introduction b • H 3 N···Cu. Cl and H 3 N···Ag. Cl • • Symmetric top C 3 v point group symmetry – – a Bittner et al, J. Chem. Phys. 142, 144302 (2015) Mikhailov et al, Chem. Phys. Lett. 499, 16 (2010) • (CH 3)3 N···HX, H 3 N···HX, (CH 3)3 P···HX and H 3 P···HX • • Proton transfer upon coordination to (CH 3)3 N Regular hydrogen bonded complex upon coordination to H 3 N, (CH 3)3 P and H 3 P – Legon et al, Chem. Soc. Rev. 22, 153 (1993) • (CH 3)3 N···XY, H 3 N··· XY and H 3 P···XY • • Stronger halogen bond formed by (CH 3)3 N then H 3 N and H 3 P induce the largest charge transfer between the halide and from the base to the halides

Experimental • ~2. 5% NH 3 or (CH 3)3 N and ~1. 0% CF 3 I in 6 bar argon • ~2 K rotational temperature Zaleski et al, Phys. Chem. Phys. 16, 25221 (2014)

Spectra ~2. 5% NH 3 and ~1. 0% CF 3 I in 6 bar argon CF 3 I···NH 3 ~600, 000 averages ~20 hours Ag. I 8000 7. 0 -18. 5 GHz 10000 12000 14000 Frequency/MHz 16000 18000

H 3 N··· 107 Ag. I + CF 3 I···NH 3 J=19 -20 Arb Intensity K=0 H 3 N··· 109 Ag. I 17250 17300 Frequency/MHz 8000 10000 K=1 17315 12000 14000 Frequency/MHz 17320 Frequency/MHz 16000 H 3 N··· 107 Ag. I simulation 17325 18000

~2. 5% (CH 3)3 N and ~1. 0% CF 3 I in 6 bar argon (CH 3)3 N··· 107 Ag. I (CH 3)3 N··· 109 Ag. I J=16 -17 14615 14620 14625 Frequency/MHz 14630 ~720, 000 averages ~1 day 8000 10000 12000 14000 Frequency/MHz 16000 18000

Spectroscopic constants H 3 N D 3 N H 315 N ⁞ ⁞ ⁞ 107 Ag. I 109 Ag. I B 0 / MHz 866. 0728(7) 862. 334(1) 808. 392(1) 805. 381(1) 850. 2065(2) 846. 6861(3) DJ / Hz 75. 55(342) 80. 7(79) 54. 73(421) 59. 99(544) 60. 6(12) 65. 1(19) DJK / k. Hz 8. 82(11) 8. 70(31) 7. 25(12) 7. 25(16) 8. 66(10) 8. 64(20) χaa(I)/ MHz -796. 29(88) -796. 33(92) -794. 39(69) -794. 17(92) -797. 03(20) -796. 90(28) N 8 17 14 16 32 17 r. m. s. / k. Hz 2. 4 11. 0 4. 8 6. 7 4. 8 6. 5 Fitted using PGOPHER by Colin Western

Spectroscopic constants (CH 3)3 N ⁞ 107 Ag. I (CH 3)3 N ⁞ 109 Ag. I (CD 3)3 N ⁞ 107 Ag. I (CD 3)3 N ⁞ 109 Ag. I B 0 / MHz 430. 2115(1) 429. 9729(1) 389. 8318(4) 389. 7005(3) DJ / Hz 14. 20(22) 14. 16(25) 9. 37(71) 11. 57(51) DJK / k. Hz 0. 9907(63) 1. 0012(58) 0. 857(21) 0. 796(12) χaa(I) / MHz -784. 22(75) -786. 03(68) -784. 1(27) -786. 2(23) N 60 59 35 21 r. m. s/ k. Hz 6. 7 7. 6 13. 0 8. 9

Structure r 0 rs re(CCSD(T)(F 12*)/ AVQZ) r(I-Ag) 2. 5373(5) Å - 2. 5457 Å r(Ag-N) 2. 181(2) Å 2. 1822(19) Å 2. 1767 Å r(N-H) [1. 0131 Å] - 1. 0131 Å (Ag-N-H) 110. 97(8)ᵒ - 111. 64ᵒ

Force constants • Pseudo diatomic model • Millen’s model – D. J. Millen. Can. J. Chem. , 63, 1477 (1985) k(N-Ag) H 3 N··· 107 Ag. I (CH 3)3 N··· 107 Ag. I Pseudo diatomic 35. 8(16)/ N m-1 69. 3(11)/ N m-1 Millen’s model 12. 5(6)/ N m-1 43. 7(7)/ N m-1

Ionicity 107 Ag. I χaa(I) ic /MHz -1062. 262(100) 0. 54 H 3 N··· 107 Ag. I -796. 29(88) 0. 65 (CH 3)3 N··· 107 Ag. I -784. 22(75) 0. 66 H 3 P··· 107 Ag. I 1 -733. 8(34) 0. 68 Walker, N. R. , et al. "Microwave Spectrum and Geometry of H 3 P···Ag. I. " 67 th International Symposium on Molecular Spectroscopy. 2012. 1

Summary • The rotational spectra of H 3 N···Ag. I and (CH 3) 3 N···Ag. I were fitted to a symmetric top Hamiltonian • Relative intensities of K=0, 1, 2 in H 3 N···Ag. I suggest a C 3 v point group symmetry • The force constant was found to be stronger in (CH 3) 3 N···Ag. I than H 3 N···Ag. I and induce a larger change transfer to the iodine

Acknowledgments The Group: Nick Walker Daniel Zaleski John Mullaney Tony Legon (University of Bristol) Susanna Stephens (University of Manitoba) David Tew (University of Bristol)