Microwave Spectra and Structures of H 2 S-CuCl and H 2 O-CuCl Nicholas R. Walker, Felicity J. Roberts, Susanna L. Stephens, David Wheatley, Anthony C. Legon by 1 Rod rotator Laser arm Gas line attached to solenoid valve Microwave emission antenna O H CuCl

Objectives Apply microwave spectroscopy to study interactions of the broadest significance in inorganic chemistry. Examples include complexes formed between CO, H 2 S, H 2 O, NH 3 and the noble metal atoms Cu and Ag. Establish laser ablation as a general method for the production of metal-ligand complexes for study by microwave spectroscopy. Compare units such as H 2 S-CuCl, H 2 O-CuCl with their hydrogen- bonded analogues, H 2 S-HCl, H 2 O-HCl to identify common trends. Previous works include studies of OC-MX by Gerry and co-workers. Also N 2 -MX and H 2 S-MX by Walker, Legon and co-workers.

To vacuum Fixed mirror Adjustable mirror Adiabatic expansion of CCl 4 / H 2 O / Ar Solenoid valve Gas line Copper rod and rod rotater 532 nm Nd:YAG laser Focusing lens Connections to microwave emission and detection circuits Balle-Flygare FTMW spectrometer Rod rotater Laser arm

θ HOH End view Near-prolate, asymmetric top of C s symmetry. Dipole moment on a axis, Expect a-type transitions. c-type transitions outside the operating range of the spectrometer. Sensitive to  A, r M-Cl, r M-S. Cannot determine  HOH, r O-H c b H 2 O-CuCl AA r M-O r Cu-Cl O H CuCl rO-HrO-H Side view a c

J KaKc ′-J KaKc ′′ =2-1 ~9700 MHz J KaKc ′-J KaKc ′′ =3-2 ~14600 MHz Frequency / MHz H 2 O-CuCl

Frequency / MHz 8000 gas pulses 1400 gas pulses Sim. Exp. Sim MHz MHz MHz H 2 O-CuCl J ′ Ka ′ Kc ′ -J ′′ Ka ′′ Kc ′′ = F 1 ′ -F 1 ′′, F ′ -F ′′ = J ′ Ka ′ Kc ′ -J ′′ Ka ′′ Kc ′′ = , 3-2 F 1 ′ -F 1 ′′, F ′ -F ′′ =, 2-1 F 1 ′ -F 1 ′′, F ′ -F ′′ =, 4-3 ~10 kHz Exp.

F 1 ′ -F 1 ′′, F ′ -F ′′ =, 5-4 J ′ Ka ′ Kc ′ -J ′′ Ka ′′ Kc ′′ = gas pulses ~20 kHz Frequency / MHz K a = MHz Exp. Sim.

Frequency / MHz J KaKc ′-J KaKc ′′ =3-2 H 2 O-CuCl Central components which have K a =0 Components which have K a =1 Function of B 0 -C 0 Hyperfine structure arising from two quadrupolar nuclei (Cu, Cl).

V( φ)/cm -1 φ/deg 39.1 º V = “Identification and molecular geometry of a weakly bound dimer (H 2 O,HCl) in the gas phase by rotational spectroscopy” A. C. Legon and L. C. Willoughby, Chem. Phys. Letters, 95, , (1983).

H 2 O- 63 Cu 35 ClH 2 O- 65 Cu 35 Cl B 0 + C 0 / MHz (9) (10) B 0 - C 0 / MHz (48) (65)  J  10 3 / kHz 0.551(28)0.518(31)  JK  10 3 / kHz 63.96(19)64.25(27) / MHz (85) (27) / MHz (48) a / MHz (12) (75) / MHz-0.808(34) a / kHz17.2(59)17.2 b / kHz17.67(71)17.67 b a Fixed at value for H 2 O- 63 Cu 35 Cl multiplied by ratio of nuclear quadrupole moments for the copper ( 65 Cu/ 63 Cu) isotopes. b Fixed at value for H 2 O- 63 Cu 35 Cl. c Numbers in parentheses are standard deviation in units of last significant figure. 10 isotopologues studied including substitutions at every atom. 47 F′-F′′ transitions measured for H 2 O- 63 Cu 35 Cl isotopologue, standard deviation of fit = 3.2 kHz.

H 2 O-CuClH 2 S-CuClCuCl r Cu-Cl / Å 2.059(4)2.0631(3)*2.051 (r e ) r Cu-L / Å 1.918(8)2.1532(3)*-  / ˚ 39.8(11)73.956(15)*- *No isotopic substitution available at sulphur atom. Structure Determination

Conclusions Acknowledgments Microwave spectrum of H 2 O-CuCl assigned and structure determined. Molecule is either C 2v planar at equilibrium or the potential energy barrier to inversion is low enough that the v=0 and 1 states (associated with inversion of the water molecule) are well separated. Financial Support Felicity J. Roberts Susanna L. Stephens Victor A. Mikhailov Anthony C. Legon Engineering and Physical Sciences Research Council Colin M. Western – work developing PGOPHER for microwave spectroscopy. (Talk on Tuesday at 8:47 a.m., McPherson Lab., TC02). David P. Tew Jeremy N. Harvey