Extremely
Bulky Amido First Row Transition Metal(II) Halide Complexes: Potential
Precursors to Low Coordinate Metal–Metal Bonded Systems
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Abstract
Reactions
of the extremely bulky potassium amide complexes, [KL′(η<sup>6</sup>-toluene)] or [KL″] (L′/L″ = N(Ar*)(SiR<sub>3</sub>), Ar* = C<sub>6</sub>H<sub>2</sub>{C(H)Ph<sub>2</sub>}<sub>2</sub>Me-2,6,4; R = Me (L′) or Ph (L″)), with a series
of first row transition metal(II) halides have yielded 10 rare examples
of monodentate amido first row transition metal(II) halide complexes,
all of which were crystallographically characterized. They encompass
the dimeric, square-planar chromium complexes, [{CrL′(THF)(μ-Cl)}<sub>2</sub>] and [{CrL″(μ-Cl)}<sub>2</sub>], the latter
of which displays intramolecular η<sup>2</sup>-Ph···Cr
interactions; the dimeric tetrahedral complexes, [{ML′(THF)(μ-Br)}<sub>2</sub>] (M = Mn or Fe), [{ML″(THF)(μ-X)}<sub>2</sub>] (M = Mn, Fe or Co; X = Cl or Br) and [{CoL″(μ-Cl)}<sub>2</sub>] (which displays intramolecular η<sup>2</sup>-Ph···Co
interactions); and the monomeric zinc amides, [L′ZnBr(THF)]
(three-coordinate) and [L″ZnBr] (two-coordinate). Solution
state magnetic moment determinations on all but one of the paramagnetic
compounds show them to be high-spin systems. Throughout, comparisons
are made with related bulky terphenyl transition metal(II) halide
complexes, and the potential for the use of the prepared complexes
as precursors to low-valent transition metal systems is discussed
