# TOO SHORT CN BOND LENGTHS FOUND IN Fe, Co, AND Ni ISOCYANIDE AND CYANIDES

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 Title: TOO SHORT CN BOND LENGTHS FOUND IN Fe, Co, AND Ni ISOCYANIDE AND CYANIDES Creators: Hirano, Tsuneo; Fukui, Rei; Nagashima, Umpei Issue Date: 2004 Publisher: Ohio State University Abstract: We were surprised, thinking it might be a misprint, with such a short C-N bond length, 1.03(8) {\AA}, of $\hat{X}^{6}\Delta$ FeNC when the Lie and Dagdigian paper (2001) on FeNC by $LIF^{a}$ came out. Ziurys and Sheridan aslo found a short CN bond length for the $\hat{X}$ CoCN, 1.13133 \AA, by MW, last $year.^{b}$ For $\hat{X}^{2}\Delta_{i}$ NiCN, Kingston and $Merer^{c}$ has reported a little short CN bond length of $1.1591(29) \AA$, determined by LIF, and Sheridan and $Ziurys^{d}$ $1.1580(8) \AA$ by MW. Our ab initio calculated $r_{e}$ values, though some of them are preliminary at the moment, are 1.172 (FeNC), 1.171 (CoCN), and 1.166 \AA (NiCN). The discrepancy between experimental and theoretical values is in the order $FeNC > CoCN > NiCN$, in parallel with the expected ionic character of the metal-ligand bond and accordingly with the floppy character of the bending motion. The observed too-short CN bond lengths in these radicals probably come from the inadequate model used for the analysis of observed spectra. A new model will be proposed, and calculations of the three dimensional potential energy surfaces for $\hat{X}^{6}\Delta$ FeNC/FeCN, which are necessary for the theoretical analysis based on the new model, are in progress at the level of $MR-SDCI+Q$ with Roos-ANO (Fe) and aug-cc-pVQZ (C and N) basis sets. Description: $^{a}$ J. Lie and P. J. Dagdigian, J. Chem. Phys. 114, 2137 (2001). $^{b}$ P.M. Sheridan and L.M. Ziurys, University of Arizona, Private communication (2003). $^{c}$ C.T. Kingston, AJ. Merer, and T.D. Varberg, J. Mole. Spectrosc, 215, 106 (2002). $^{d}$ P.M. Sheridan and L.M. Ziurys, J. Chem. Phys., 118, 6370 (2003). Author Institution: Grid Technology Research Center, Institute of Advanced Industrial Science and Technology 6-9-3 Ueno URI: http://hdl.handle.net/1811/21302 Other Identifiers: 2004-RF-05