Cyanides and Isocyanides of First-Row Transition Metals: Molecular Structure, Bonding, and Isomerization Barriers

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• 作者：Ví ; ctor M. Ray&oacute ; n ; Pilar Redondo ; Haydee Valdé ; s ; Carmen Barrientos ; Antonio Largo
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：July 19, 2007
• 年：2007
• 卷：111
• 期：28
• 页码：6334 - 6344
• 全文大小：137K
• 年卷期：v.111,no.28(July 19, 2007)
• ISSN：1520-5215

文摘

Cyanides and isocyanides of first-row transition metal M(CN) (M = Sc-Zn) are investigated with quantumchemistry techniques, providing predictions for their molecular properties. A careful analysis of the competitionbetween cyanide and isocyanide isomers along the transition series has been carried out. In agreement withthe experimental observations, late transition metals (Co-Zn) clearly prefer a cyanide arrangement. On theother hand, early transition metals (Sc-Fe), with the only exception of the Cr(CN) system, favor the isocyanideisomer. The theoretical calculations predict the following unknown isocyanides, ScNC(³ges/gifchars/Delta.gif" BORDER=0 >), TiNC(⁴ges/gifchars/Phi.gif" BORDER=0 >), VNC(⁵ges/gifchars/Delta.gif" BORDER=0 >), and MnNC(⁷ges/gifchars/Sigma.gif" BORDER=0 >⁺), and agree with the experimental observation of FeNC(⁶ges/gifchars/Delta.gif" BORDER=0 >) and the CrCN(⁶ges/gifchars/Sigma.gif" BORDER=0 >⁺) cyanide.First-row transition metal cyanides and isocyanides are predicted to have relatively large dissociation energieswith values within the range 80-101 kcal mol^-1, except Zn(CN), which has a dissociation energy around50-55 kcal mol^-1, and low isomerization barriers. A detailed analysis of the bonding has been carried outemploying the topological analysis of the charge density and an energy decomposition analysis. The role ofthe covalent and electrostatic contributions to the metal-ligand bonding, as well as the importance of ges/gifchars/pi.gif" BORDER=0 >bonding, are discussed.