Molecular Structure of an Fe(IV) Species:  {[Fe(TTP)]₂N}SbCl₆

Abstract

The molecular structure of the formal iron(IV) porphyrinate derivative, [[Fe(TTP)]2N]SbCl6 (TTP = tetratolylporphyrinate), is reported. The structural parameters are compared to the previously reported species [Fe(TPP)]2N, in which the iron oxidation state is +3.5. Both the equatorial and axial bond distances in [[Fe(TTP)]2N]SbCl6 are slightly shortened and consistent with an increased formal charge on iron. The value for the axial Fe-N distance is 1.6280(7) A, and the average value of the equatorial Fe-Np distances is 1.979(5) A. The Mössbauer isomer shift decreases upon oxidation, again consistent with an increase in formal charge. Values for the isomer shift at room temperature are -0.13 mm/s for [[Fe(TTP)]2N]SbCl6 and 0.04 mm/s for [Fe(TTP)]2N. Crystal data for [[Fe(TTP)]2N]SbCl6 are as follows: orthorhombic, space group Fddd, Z = 8, a = 23.689(2) A, b = 31.056(3) A, c = 22.7788(18) A.

Mid- to high-valent imido and nitrido complexes of iron

“…For instance, azide photolysis has provided nitride bridged diiron complexes in which the iron centers are supported by tetradentate macrocycles such as tetraphenylporphyrin, cyclam derivatives, and phthalocyanines, 16 [57][58][59][60]. A number of high-valent nitride bridged species have been reported, and valencetautomerism may be prevalent in some of these high-valent systems [61].…”

Self‐Assembly of a Tetradecanuclear Iron Nitride Cluster

“…The desired clusters possess nuclearities exceeding two, differentiating them from various binuclear species with Fe-N-Fe bridges, [6][7][8][9][10] and are devoid of the carbonyl ligands present in interstitial low-valent clusters such as [Fe 5 (m 5 -N)(CO) 14 ]…”

Bio‐organometallic Approaches to Nitrogen Fixation Chemistry

“…Holm and coworkers have recently begun to examine the coordination chemistry of iron nitrides to see if a nitride which bridges six iron centers can be obtained [96]. Literature precedent shows ample evidence for linear Fe-N-Fe bridges for octahedrally coordinated iron [97][98][99][100] and, more recently, a bent Fe-N-Fe bridge for pseudotetrahedral iron centers from our laboratory at Caltech (vide infra) [89, 3.3 Biomimetic Systems that Model Structure and Function 105 …”