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Saouma CT, Muller P, Peters JC: Characterization of structurally unusual diiron N (x) H (y) complexes. . J Am Chem Soc. 2009 Aug 5;131(30):10358-9.
A series of fascinating diiron complexes featuring bridging N (x) H (y) ligands stabilized by tris (phosphine) borate ([PhB (CH (2) PR (2))(3)] = [PhBP (R)(3)]) ligands have been characterized. Hydrazine activation by [PhBP (R)(3)] Fe-Me (R = Ph or cyclohexylmethyl) leads to diiron Fe (2)(mu-eta (1):eta (1)-N (2) H (4))(mu-eta (2):eta (2)-N (2) H (2)) complexes featuring both bridging hydrazine and hydrazido ligands. Thermolysis of {[PhBP (CH (2))(Cy)(3)] Fe}(2)(mu-eta (1):eta (1)-N (2) H (4))(mu-eta (2):eta (2)-N ( 2) H (2)) at 22 degrees C leads to a structurally unusual {[PhBP (CH (2))(Cy)] Fe}(2)(mu-eta (1):eta (1)-N (2) H (2))(mu-NH (2))(2) complex featuring bridging HN horizontal lineNH and NH (2)(-) ligands. This contrasts with {[PhBP (Ph)(3)] Fe}(2)(mu-eta (1):eta (1)-N (2) H (4))(mu-eta (2):eta (2)-N (2) H (2)) , which can be chemically oxidized to produce either {[PhBP (Ph)(3)] Fe}(2)(mu-eta (1):eta (1)-N (2) H (2))(mu-eta (2):eta (2)-N (2) H (2)) or {[PhBP (Ph)(3)] Fe}(2)(mu-NH)(2), depending on the conditions. The former product is the only known complex to contain bridging N (2) H (2) ligands in each of their limiting states of oxidation (HN horizontal lineNH vs HN-NH (2-)). The latter product constitutes the first example of a diiron Fe (2)(mu-NH)(2) diamond-shaped core. |
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