Extremely Bulky Amido First Row Transition Metal(II) Halide Complexes: Potential Precursors to Low Coordinate Metal–Metal Bonded Systems

Reactions of the extremely bulky potassium amide complexes, [KL′(η6-toluene)] or [KL″] (L′/L″ = N­(Ar*)­(SiR3), Ar* = C6H2{C­(H)­Ph2}2Me-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)}2] and [{CrL″(μ-Cl)}2], the latter of which displays intramolecular η2-Ph···Cr interactions; the dimeric tetrahedral complexes, [{ML′(THF)­(μ-Br)}2] (M = Mn or Fe), [{ML″(THF)­(μ-X)}2] (M = Mn, Fe or Co; X = Cl or Br) and [{CoL″(μ-Cl)}2] (which displays intramolecular η2-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.