XAS characterization of a nitridoiron(IV) complex with a very short Fe-N bond.
X-ray absorption spectroscopy has been used to characterize the novel nitridoiron(IV) units in two [PhBPR3]Fe(N) complexes (R=iPr and CyCH2) and obtain direct spectroscopic evidence for a very short Fe-N distance. The distance of 1.51-1.55 A reflects the presence of an FeN triple bond in accord with the observed FeN vibration observed for one of these species (nuFeN=1034 cm(-1)). This highly covalent bonding interaction results in the appearance of an unusually intense pre-edge peak, whose estimated area of 100(20) units is much larger than those of the related tetrahedral complexes with FeI-N2-FeI, FeII-NPh2, and FeIIINAd motifs, and those of recently described six-coordinate FeVN and FeVIN complexes. The observation that the FeIV-N distances of two [PhBPR3]Fe(N) complexes are shorter than the FeIV-O bond lengths of oxoiron(IV) complexes may be rationalized on the basis of the greater pi basicity of the nitrido ligand than the oxo ligand and a lower metal coordination number for the Fe(N) complex.
Rohde
Jan-Uwe
JU
Department of Chemistry and Center for Metals in Biocatalysis, 207 Pleasant Street Southeast, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Betley
Theodore A
TA
Jackson
Timothy A
TA
Saouma
Caroline T
CT
Peters
Jonas C
JC
Que
Lawrence
L
D007501:Iron / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D013053:Spectrophotometry; D014965:X-Rays
D058085:Iron Compounds; D007501:Iron; D009584:Nitrogen