Systematic variation of metal-metal bond order in metal-chromium complexes

Laura J. Clouston, Randall B. Siedschlag, P. Alex Rudd, Nora Planas, Shuxian Hu, Adam D. Miller, Laura Gagliardi, Connie C. Lu

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

In the field of metal-metal 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-chromium complex, three additional M-Cr 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-Cr complex has an ultrashort metal-metal bond distance of 1.82 Å, which is consistent with a quintuple bond. The M-Cr 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-Cr 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' 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-Cr pair.

Original languageEnglish (US)
Pages (from-to)13142-13148
Number of pages7
JournalJournal of the American Chemical Society
Volume135
Issue number35
DOIs
StatePublished - Sep 4 2013

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