High-Resolution Infrared Spectrum of the  1 band of 5-C5H5NiNO Chandana Karunatilaka, Davian Pedroza, Stephen G. Kukolich Department of Chemistry, 1306E. University Blvd., University of Arizona, Tucson, AZ, 85721, USA. Ranga Subramanian Department of Chemistry, Tulane University, New Orleans, LA 70118, USA. Deanne J. Idar Los Alamos National Laboratory, P.O.Box 1663, Los Lamos, NM, 87545, USA.

Cyclopentadienylnickel nitrosyl, 5-C5H5NiNO -bonded Transition metal complex • Prolate Symmetric-top • Point group – C5v (Microwave Spectroscopy) A.P.Cox, L.F.Thomas, and J.Sheridan, Nature 181 (1958) 1157. Ni-N-O moiety is linear. (Electron Diffraction & Microwave studies) Ronova, N.V.Aleskeeva, N.N.Veniamikov and M.Kravers, J.Struct.Chem.16 (1975) 441. Cox, A.P; Brittain, A.H. Transaction of the Faraday Society (1970), 66(3), 557-62.

Importance  Polymerization of terminal alkynes Excellent catalyst  Cyclo-oligomerization of di-alkenes  Polymerization of terminal alkynes One of the first organometallic molecules to be studied using Microwave Spectroscopy.

Previous Spectroscopic studies • Low Resolution IR Spectroscopy  IR and Raman active frequencies • Microwave Spectroscopy  Structure in v = 0 level  14N quadrupole coupling strength • Photoelectron Spectroscopy  Orbital energies  Ionization energies R.D.Feltham, and W.G.Fately, Spectrochim. Acta. 20 (1964) 1081. S.G.Kukolich, J.V.Rund, D.J.Pauley, and R.E.Bumgarner, JACS. 110 (1988) 7356. A.P.Cox, J.Randall, and A.C.Legon, Chem.Phys. Lett. 153 (1988) 253. Xiaorong Li, J.S.Tse, G.M.Bancroft, R.J.Puddephatt, K.H.Tan, Inorg. Chem. (1996) 35(9) 2515. • PRESENT STUDY  High Resolution Infrared spectrum ( rovibrational structure)

Experiment (C5H5)2Ni C5H5NiNO Nickelocene Pentane / ice temp. Purge NO gas for 6-7 hrs bright red liquid Source Sample in Vacuum FT Spectrometer - Kitt Peak Arizona (built by Jim Brault) Computer sample cell

Data Analysis • Line list for the center frequency  PC-GREMLIN* • Fundamental vibration  A1 - symmetric stretch of C-H • Transition dipole moment  // symmetry axis IR active parallel ( // ) band * Dr. Ram S. Ram provided this program.

Data Analysis • Altogether 24 lines  SPFIT** fitting program [rigid-rotor Hamiltonian & centrifugal distortion constants] • Four adjustable parameters  rotational constants for v = 1 ( A , B  )  B rotational constant for v = 0 ( B  )  vibration band center ( 0 ) • Neglected nuclear quadrupole coupling of 14N  (much smaller!) • Fixed distortion constants to previous microwave values. **H.M.Pickett , J.Mol.Spectroscopy 148 (1991) 371 .

The structural parameters obtained for the CpNiNO complex (in cm-1) a : FTMW values b: Low Resolution IR value c: Fixed to DFT (theory)

Results • Rotational constants  Ground (B ) & Excited vibrational states (A , B ) B  - B  = 0.00065 cm-1 A = 0.14324(8) cm-1  Consistent with DFT values Fundamental C-H stretching frequency = 3110.414(1) cm-1 Agree very well (<1%) with the previous FTMW , IR & current DFT results • Present High Resolution IR data Understand the structure in the v = 1 state

Acknowledgements Dr. Michael Dulick – Kitt Peak National Observatory, Arizona. Dr. Ram S. Ram - University of Arizona.

Thank you for your attention !