Systematic Variation of Metal鈥揗etal Bond Order in Metal鈥揅hromium Complexes

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• 作者：Laura J. Clouston ; Randall B. Siedschlag ; P. Alex Rudd ; Nora Planas ; Shuxian Hu ; Adam D. Miller ; Laura Gagliardi ; Connie C. Lu
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：September 4, 2013
• 年：2013
• 卷：135
• 期：35
• 页码：13142-13148
• 全文大小：382K
• 年卷期：v.135,no.35(September 4, 2013)
• ISSN：1520-5126

文摘

In the field of metal鈥搈etal bonding, the occurrence of stable, multiple bonds between different transition metals is uncommon, and is largely unknown for different first-row metals. Adding to a recently reported iron鈥揷hromium complex, three additional M鈥揅r complexes have been isolated, where the iron site is systematically replaced with other first-row transition metals (Mn, Co, or Ni), while the chromium site is kept invariant. These complexes have been characterized by X-ray crystallography. The Mn鈥揅r complex has an ultrashort metal鈥搈etal bond distance of 1.82 脜, which is consistent with a quintuple bond. The M鈥揅r bond distances increases across the period from M = Mn to M = Ni, as the formal bond order decreases from 5 to 1. Theoretical calculations reveal that the M鈥揅r bonds become increasingly polarized across the period. We propose that these trends arise from increasing differences in the energies and/or contraction of the metals鈥?d-orbitals (M vs Cr). The cyclic voltammograms of these heterobimetallic complexes show multiple one-electron transfer processes, from two to four redox events depending on the M鈥揅r pair.