TY - JOUR
T1 - Structure and Reactivity of a Bis(μ-acetato-O,O′diiron(II) Complex, [Fe2(O2CCH3)2(TPA)2](BPh4)2. A Model for the Diferrous Core of Ribonucleotide Reductase
AU - Ménage, Stéphane
AU - Zang, Yan
AU - Hendrich, Michael P.
AU - Que, Lawrence
PY - 1992/9/1
Y1 - 1992/9/1
N2 - [Fe2(O2CCH3)2(TPA)2](BPh4)2 (1, TPA = tris(2-pyridylmethyl)amine) serves as a model for the diferrous core of ribonucleotide reductase. 1 crystallizes in the space group P1 (a = 10.923 (8) Å, b = 12.416 (4) Å, c = 13.935 (3) Å, α = 105.03 (3)°, β = 95.38 (3)°, γ = 92.53 (3)°, Z = 1) with an inversion center located in the center of the bis(μ-acetato)diiron(II) core. The acetates coordinate to the two Fe(II) centers in a syn-anti mode, affording an Fe-Fe separation of 4.288 (2) Å, and mediate a weak antiferromagnetic interaction between the metal centers (H = −2JS1,•S2, J ~ −1 cm−1). This dimeric structure appears to partially dissociate into monomeric units in solution, as indicated by its NMR and EPR spectra. Exposure of 1 to 02 results in an immediate reaction forming [Fe2O(O2CCH3)2(TPA)2](BPh4)2 (2), a (μ-oxo)diferric TPA complex with terminal monodentate acetates, which in turn converts readily to the previously characterized [Fe2O(μ-O2CCH3)(TPA)2]3+ complex (9) in the presence of protic solvents. Complexes 1, 2, and 9 represent structural motifs associated with the diiron core of ribonucleotide reductase in its diferrous and diferric oxidation states. The structural changes observed in the autoxidation of 1 mimic putative changes in the diiron site that occur in the O2-dependent formation of oxidized ribonucleotide reductase from its reduced counterpart.
AB - [Fe2(O2CCH3)2(TPA)2](BPh4)2 (1, TPA = tris(2-pyridylmethyl)amine) serves as a model for the diferrous core of ribonucleotide reductase. 1 crystallizes in the space group P1 (a = 10.923 (8) Å, b = 12.416 (4) Å, c = 13.935 (3) Å, α = 105.03 (3)°, β = 95.38 (3)°, γ = 92.53 (3)°, Z = 1) with an inversion center located in the center of the bis(μ-acetato)diiron(II) core. The acetates coordinate to the two Fe(II) centers in a syn-anti mode, affording an Fe-Fe separation of 4.288 (2) Å, and mediate a weak antiferromagnetic interaction between the metal centers (H = −2JS1,•S2, J ~ −1 cm−1). This dimeric structure appears to partially dissociate into monomeric units in solution, as indicated by its NMR and EPR spectra. Exposure of 1 to 02 results in an immediate reaction forming [Fe2O(O2CCH3)2(TPA)2](BPh4)2 (2), a (μ-oxo)diferric TPA complex with terminal monodentate acetates, which in turn converts readily to the previously characterized [Fe2O(μ-O2CCH3)(TPA)2]3+ complex (9) in the presence of protic solvents. Complexes 1, 2, and 9 represent structural motifs associated with the diiron core of ribonucleotide reductase in its diferrous and diferric oxidation states. The structural changes observed in the autoxidation of 1 mimic putative changes in the diiron site that occur in the O2-dependent formation of oxidized ribonucleotide reductase from its reduced counterpart.
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U2 - 10.1021/ja00046a026
DO - 10.1021/ja00046a026
M3 - Article
AN - SCOPUS:4243620709
SN - 0002-7863
VL - 114
SP - 7786
EP - 7792
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 20
ER -