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2,2′-Pyridylpyrrolide Ligand Redistribution Following Reduction
journal contribution
posted on 2013-05-06, 00:00 authored by Keith Searles, Atanu K. Das, René W. Buell, Maren Pink, Chun-Hsing Chen, Kuntal Pal, David Gene Morgan, Daniel J. Mindiola, Kenneth G. CaultonThe potential redox activity of the
2,2′-pyridylpyrrolide
ligand carrying two CF3 substituents (L2) is
investigated. Synthesis and characterization of d6 and
d7 species M(L2)2 for M = Fe and
Co are described (both are nonplanar, but not tetrahedral), as are
the Lewis acidity of each. In spite of CV evidence for quasireversible
reductions to form M(L2)2q– where q = 1 and 2, chemical reductants
instead yield divalent metal complexes KM(L2)3, which show attractive interactions of K+ to pyrrolide,
to F, and to lattice toluene π cloud. The collected evidence
on these products indicates that pyridylpyrrolide is a weak field
ligand here, but CO can force spin pairing in Fe(L2)2(CO)2. Evidence is presented that the overall reductive
reaction yields 33 mol % of bulk metal, which is the fate of the reducing
equivalents, and a mechanism for this ligand redistribution is proposed.
Analogous ligand redistribution behavior is also seen for nickel and
for trimeric monovalent copper analogues; reduction of Cu(L2)2 simply forms Cu(L2)2–.
