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'(eta(6)-toluene)] or [KL ''] (L'/L '' = N(Ar*)(SiR3), Ar* = C6H2{C(H)Ph-2}(2)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)(mu-Cl)}(2)] and [{CrL ''(mu-Cl)}(2)], the latter of which displays intramolecular eta(2)-Ph center dot center dot center dot Cr interactions; the dimeric tetrahedral complexes, [{ML'(THF)(mu-Br)}(2)] (M = Mn or Fe), [{ML ''(THP)(mu-X)}(2)] (M = Mn, Fe or Co; X = Cl or Br) and [{CoL ''(mu-Cl)}(2)] (which displays intramolecular mu-Ph center dot center dot center dot 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 lowvalent transition metal systems is discussed.