Unexpected assembly of a novel triply bridged diiron(II) core by a bidentate Schiff base ligand
摘要:
The unusual dinucleating properties of a simple bidentate Schiff base (LH, 1) in the presence of weakly coordinating methanol solvent lead to the self-assembly of [Fe-2(II)(L-b)(2) (L-t)(2)(mu-MeOH)] (2) (b and t refer to bridging and terminally bound ligands, respectively). Complex 2 is the first diiron(II) species in which the two metal centers are triply bridged by single atoms in an asymmetric fashion, involving both mu-O-Ph and mu-OHMe bridges. This binding mode produces an Fe center dot center dot center dot Fe distance of 3.139(1) angstrom. Dinucleation appears to be driven by a combination of ligand deficiency and solvent-mediated chemistry reminiscent of host-guest interactions. The presence of a mu-MeOH ligand is unprecedented in iron chemistry. Parallel-mode EPR spectra of complex 2 recorded at 4 K show an intense negative signal at g(parallel to) approximate to 16, suggesting the dimeric form exists in solution. (C) 2007 Elsevier B.V. All rights reserved.