Density Functional Study of N2 Activation by Molybdenum(III) Complexes. Unusually Strong Relativistic Effects in 4d Metal Compounds

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• 作者：Konstantin M. Neyman ; Vladimir A. Nasluzov ; Jutta Hahn ; Clark R. Landis ; and Notker Rö ; sch
• 刊名：Organometallics
• 出版年：1997
• 出版时间：March 4, 1997
• 年：1997
• 卷：16
• 期：5
• 页码：995 - 1000
• 全文大小：194K
• 年卷期：v.16,no.5(March 4, 1997)
• ISSN：1520-6041

文摘

All-electron generalized-gradient density functional(DF) calculations have been carriedout on both the nonrelativistic and relativistic levels to address themechanism of N₂ cleavageby L₃Mo(III) complexes. The reactionfeatures computed for the model reactants with L =NH₂, NMe₂, and Me are compared to the recentlypublished values for the(H₂N)₃Moderivative obtained with the help of the effective core potential (ECP)DF method and tothe experimental data reported for the reaction of N₂ with(RArN)₃Mo (R =C(CD₃)₂CH₃, Ar= 3,5-C₆H₃Me₂). Despitea qualitative agreement between the reaction parameters ofthepresent relativistic and the previous ECP DF calculations, someimportant quantitativedifferences are found, like a lower activation barrier by more than 10kJ mol^-1 and a higheroverall reaction exothermicity by about 80 kJ mol^-1.The influence of the electronic andsteric properties of the ligands L on the parameters of the cleavagereaction has beenanalyzed. The Mo(III) trialkyl complexes, at least those withsmall ligands, are predictedto scissor N₂ molecules less efficiently than the triamidoderivatives. The relativistic effects,which are unusually large for 4d metal compounds, have been calculatedand are attributedto the exceptionally strong MoN bonds.