Infrared spectra and density functional theory calculations of the tantalum and niobium carbonyl din.pdf

Infrared spectra and density functional theory calculations of the tantalum and niobium carbonyl dinitrogen complexes Zhang-Hui Lu,1,2 Ling Jiang,1 and Qiang Xu1,2,a
1National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan 2Graduate School of Engineering, Kobe University, Nada Ku, Kobe, Hyogo 657-8501, Japan
Received 28 May 2009; accepted 2 July 2009; published online 21 July 2009 Laser-ablated tantalum and niobium atoms react with CO and N2 mixtures in excess neon to produce carbonyl metal dinitrogen complexes, NNMCO
M =Ta, Nb,
NN2TaCO, and NNTa
CO2, as well as metal carbonyls and dinitrogen complexes. These carbonylmetal dinitrogen complexes are characterized using infrared spectroscopy on the basis of the results of the isotopic substitution and mixed isotopic splitting patterns. Density functional theory calculations have been performed on these novel species. The good agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these species from the matrix infrared spectra. Natural bond orbital analysis and plausible reaction mechanisms for the formation of the products are discussed. ? 2009 American Institute of Physics. DOI: 10.1063/1.3186759 I. INTRODUCTION The interaction of transition-metal atoms with small molecules
i.e., CO, O2, CO2, H2, N2, CH4, etc. is of con- siderable interest in the widely different fields of catalysis, synthesis, and biology.1 Among these small molecules, CO and N2 are two of the most important in transition-metal chemistry from an academic or an industrial viewpoint.1–5 Since the discovery of the first metal carbonyl Ni
CO4 and metal dinitrogen complex Ru
NH35
N22+, 6,7 the synthe- sis, structural characterization, and reactivity of transition- metal carbonyls and dinitrogen complexes have been the subject of intensive studies and are still important compo- nents of moder