Add like
Add dislike
Add to saved papers

Syntheses, crystal structures, and magnetic properties of the oxalato-bridged mixed-valence complexes (FeII(bpm)3]2[FeIII2(ox)5].8H2O and FeII(bpm)3Na(H2O)2Fe(ox)(3).4H2O (bpm = 2,2'-bipyrimidine).

Inorganic Chemistry 2001 Februrary 13
The preparation and crystal structures of two oxalato-bridged FeII-FeIII mixed-valence compounds, [FeII(bpm)3]2[FeIII2(ox)5].8H2O (1) and FeII(bpm)3Na(H2O)2FeIII(ox)(3).4H2O (2) (bpm = 2,2'-bipyrimidine; ox = oxalate dianion) are reported here. Complex 1 crystallizes in the triclinic system, space group P1, with a = 10.998(2) A, b = 13.073(3) A, c = 13.308(3) A, alpha = 101.95(2) degrees, beta = 109.20(2) degrees, gamma = 99.89(2) degrees, and Z = 1. Complex 2 crystallizes in the monoclinic system, space group P2(1)/c, with a = 12.609(2) A, b = 19.670(5) A, c = 15.843(3) A, beta = 99.46(1) degrees, and Z = 4. The structure of complex 1 consists of centrosymmetric oxalato-bridged dinuclear high-spin iron(III) [Fe2(ox)5]2- anions, tris-chelated low-spin iron(II) [Fe(bpm)3]2+ cations, and lattice water molecules. The iron atoms are hexacoordinated: six oxygen atoms (iron(III)) from two bidentate and one bisbidentate oxalato ligands and six nitrogen atoms (iron(II)) from three bidentate bpm groups. The Fe(III)-O(ox) and Fe(II)-N(bpm) bond distances vary in the ranges 1.967(3)-2.099(3) and 1.967(4)-1.995(3) A, respectively. The iron(III)-iron(III) separation across the bridging oxalato is 5.449(2) A, whereas the shortest intermolecular iron(III)-iron(II) distance is 6.841(2) A. The structure of complex 2 consists of neutral heterotrinuclear Fe(bpm)2Na(H2O)2Fe(ox)3 units and water molecules of crystallization. The tris-chelated low-spin iron(II) ([Fe(bpm)3]2+) and high-spin iron(III) ([Fe(ox)3]3-) entities act as bidentate ligands (through two bpm-nitrogen and two oxalato-oxygen atoms, respectively) toward the univalent sodium cation, yielding the trinuclear (bpm)2Fe(II)-bpm-Na(I)-ox-Fe(III)(ox)2 complex. Two cis-coordinated water molecules complete the distorted octahedral surrounding of the sodium atom. The ranges of the Fe(II)-N(bpm) and Fe(III)-O(ox) bond distances [1.968(6)-1.993(5) and 1.992(6)-2.024(6) A, respectively] compare well with those observed in 1. The Na-N(bpm) bond lengths (2.548(7) and 2.677(7) A) are longer than those of Na-O(ox) (2.514(7) and 2.380(7) A) and Na-O(water) (2.334(15) and 2.356(12) A). The intramolecular Fe(II)...Fe(III) separation is 6.763(2) A, whereas the shortest intermolecular Fe(II)...Fe(II) and Fe(III)...Fe(III) distances are 8.152(2) and 8.992(2) A, respectively. Magnetic susceptibility measurements in the temperature range 2.0-290 K for 1 reveal that the high-spin iron(III) ions are antiferromagnetically coupled (J = -6.6 cm-1, the Hamiltonian being defined as H = -JS1.S2). The magnitude of the antiferromagnetic coupling through the bridging oxalato in the magneto-structurally characterized family of formula [M2(ox)5](2m-10)+ (M = Fe(III) (1), Cr(III), and Ni(II)) is analyzed and discussed by means of a simple orbital model.

Full text links

We have located links that may give you full text access.
Can't access the paper?
Try logging in through your university/institutional subscription. For a smoother one-click institutional access experience, please use our mobile app.

For the best experience, use the Read mobile app

Mobile app image

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app

All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

By using this service, you agree to our terms of use and privacy policy.

Your Privacy Choices Toggle icon

You can now claim free CME credits for this literature searchClaim now

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app