ja0453073_si_001.pdf (3.74 MB)
0/0

Ground-State Singlet L3Fe-(μ-N)-FeL3 and L3Fe(NR) Complexes Featuring Pseudotetrahedral Fe(II) Centers

Download (3.74 MB)
journal contribution
posted on 16.02.2005 by Steven D. Brown, Jonas C. Peters
Pseudotetrahedral iron(II) coordination complexes that contain bridged nitride and terminal imide linkages, and exhibit singlet ground-state electronic configurations, are described. Sodium amalgam reduction of the ferromagnetically coupled dimer, {[PhBP3]Fe(μ-1,3-N3)}2 (2) ([PhBP3] = [PhB(CH2PPh2)3]-), yields the diamagnetic bridging nitride species [{[PhBP3]Fe}2(μ-N)][Na(THF)5] (3). The Fe−N−Fe linkage featured in the anion of 3 exhibits an unusually bent angle of approximately 135°, and the short Fe−N bond distances (Fe−Nav ≈ 1.70 Å) suggest substantial Fe−N multiple bond character. The diamagnetic imide complex {[PhBP3]FeII⋮N(1-Ad)}{nBu4N} (4) has been prepared by sodium amalgam reduction of its low-spin iron(III) precursor, [PhBP3]FeIII⋮N(1-Ad) (5). Complexes 4 and 5 have been structurally characterized, and their respective electronic structures are discussed in the context of a supporting DFT calculation. Diamagnetic 4 provides a bona fide example of a pseudotetrahedral iron(II) center in a low-spin ground-state configuration. Comparative optical data strongly suggest that dinuclear 3 is best described as containing two high-spin iron(II) centers that are strongly antiferromagnetically coupled to give rise to a singlet ground-state at room temperature.

History

Exports