A New Inorganic Ring System: Planar Fe32-SR)3in [Fe3(SR)3X6]3_—Synthesis, Structures, and Solution Conformation and Equilibrium

Mark Whitener, J. K. Bashkin, K. S. Hagen, R. H. Holm, J. J. Girerd, E. Gamp, N. Edelstein

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Abstract

Anaerobic reaction of equimolar FeX2 and RS” in acetonitrile affords the trinuclear complexes (with X = Cl and R = Ph (4a), p-tolyl (4b), 2,6-Me2C6H3(4d), and X = Br, R = Ph (4c)) isolated as Et4N+ salts. These species constitute the fourth known type of discrete Fe(II) thiolates, the others being [Fe(SR)4]2-, and The following crystallographic results were obtained (crystal system; space group; cell parameters; Z; unique data (I > 3σ(I)); R (%)). (Et4N)3 (4a): monoclinic; C2/c; a = 24.500 (6) A, b = 13.488 (3) A, c = 18.217 (5) A, β = 110.68 (2)°; 4; 2679; 4.9. (Et4N)3a = 15.07 (1) A, b = 22.38 (3) A, c = 20.46 (3) A, β = 91.5 (1)°; 4, 3311; 9.7. (Et4N)3 (4c)-MeCN: hexagonal, P62c; a = b = 13.970 (4) A, c = 18.274 (3) A; 2; 890; 5.7. The reaction system FeBr2+ NaSCH2Ph in acetonitrile yields a different type of compound with the composition (Et4N)2[Fe4(SCH2Ph)6Br4] (5): triclinic; P1; a = 12.874 (2) A, b = 13.949 (3) A, c = 43.272 (8) A, α= 94.85 (2)°, β = 94.07 (2)°, y = 114.98 (1)°; 4; 7402; 6.7. Anions of type 4 contain a new type of inorganic ring system, Fe3(jU2-SR)3, distinguished by its nearly or exactly planar conformation and unusually large Fe-S-Fe angles of ~ 140°, the largest values observed for this angle type. The phenyl groups in 4a and 4c (which has imposed C3h symmetry) are coplanar with the Fe3S3 rings. In 4d these groups are rotated by ~90° owing to the steric effects of the methyl groups. Distorted tetrahedral coordination at each Fe(II) atom is completed by two halide ligands. The planar structure is to be contrasted with the chair-type conformation of the rings in 5 and other species with adamantane-like stereochemistry. Ring conformations influence the extent of antiferromagnetic interactions in the solid state. Magnetic susceptibility data of planar 4a are fit well by two -J values at 19–22 cm-1. For [Fe4(SR)10]2_, containing adamantane-like Fe4(M2-SR)6 cages with Fe3(ji2-SR)3 rings in the chair conformation, best fits of the magnetic data give one -J value at 32 or 36 cm-1 and one or two others at 42–66 cm-1 depending on the coupling symmetry. MO calculations at the extended Huckel level on suggest that the inherently stable conformation of the ring is planar. This structure is set in large measure by the stereochemical preference of the S-Fe-S angle and by transannular nonbonded repulsions. The decrease in Cl—Cl distances from 6.6 to 3.9 A in changing from the planar to the chair conformation emphasizes the latter effect. In acetonitrile the equilibrium has been approached in both directions and is shifted to the left with decreasing temperature. At K the formation of is essentially complete. In this temperature range the magnetic moment per Fe atom is 4.1-4.2 for 4a in solution and as its crystalline Et4N+ salt. This excellent agreement establishes a planar ring conformation in solution. Thus the results of three crystal structures, MO calculations, and solution and solid state magnetic measurements collectively demonstrate that the near or exact planarity of the Fe3S3 cycles in is an intrinsic property.

Original languageEnglish
Pages (from-to)5607-5620
Number of pages14
JournalJournal of the American Chemical Society
Volume108
Issue number18
DOIs
StatePublished - 1 Jan 1986

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Adamantane
Conformations
Salts
Acetonitrile
Temperature
Anions
Ligands
Atoms
Stereochemistry
Magnetic variables measurement
acetonitrile
Magnetic moments
Magnetic susceptibility
Negative ions
Crystal structure
Crystalline materials
Crystals
Chemical analysis

Cite this

Whitener, Mark ; Bashkin, J. K. ; Hagen, K. S. ; Holm, R. H. ; Girerd, J. J. ; Gamp, E. ; Edelstein, N. / A New Inorganic Ring System : Planar Fe32-SR)3in [Fe3(SR)3X6]3_—Synthesis, Structures, and Solution Conformation and Equilibrium. In: Journal of the American Chemical Society. 1986 ; Vol. 108, No. 18. pp. 5607-5620.
@article{842280e157394b12902028c6d7478071,
title = "A New Inorganic Ring System: Planar Fe3(μ2-SR)3in [Fe3(SR)3X6]3_—Synthesis, Structures, and Solution Conformation and Equilibrium",
abstract = "Anaerobic reaction of equimolar FeX2 and RS” in acetonitrile affords the trinuclear complexes (with X = Cl and R = Ph (4a), p-tolyl (4b), 2,6-Me2C6H3(4d), and X = Br, R = Ph (4c)) isolated as Et4N+ salts. These species constitute the fourth known type of discrete Fe(II) thiolates, the others being [Fe(SR)4]2-, and The following crystallographic results were obtained (crystal system; space group; cell parameters; Z; unique data (I > 3σ(I)); R ({\%})). (Et4N)3 (4a): monoclinic; C2/c; a = 24.500 (6) A, b = 13.488 (3) A, c = 18.217 (5) A, β = 110.68 (2)°; 4; 2679; 4.9. (Et4N)3a = 15.07 (1) A, b = 22.38 (3) A, c = 20.46 (3) A, β = 91.5 (1)°; 4, 3311; 9.7. (Et4N)3 (4c)-MeCN: hexagonal, P62c; a = b = 13.970 (4) A, c = 18.274 (3) A; 2; 890; 5.7. The reaction system FeBr2+ NaSCH2Ph in acetonitrile yields a different type of compound with the composition (Et4N)2[Fe4(SCH2Ph)6Br4] (5): triclinic; P1; a = 12.874 (2) A, b = 13.949 (3) A, c = 43.272 (8) A, α= 94.85 (2)°, β = 94.07 (2)°, y = 114.98 (1)°; 4; 7402; 6.7. Anions of type 4 contain a new type of inorganic ring system, Fe3(jU2-SR)3, distinguished by its nearly or exactly planar conformation and unusually large Fe-S-Fe angles of ~ 140°, the largest values observed for this angle type. The phenyl groups in 4a and 4c (which has imposed C3h symmetry) are coplanar with the Fe3S3 rings. In 4d these groups are rotated by ~90° owing to the steric effects of the methyl groups. Distorted tetrahedral coordination at each Fe(II) atom is completed by two halide ligands. The planar structure is to be contrasted with the chair-type conformation of the rings in 5 and other species with adamantane-like stereochemistry. Ring conformations influence the extent of antiferromagnetic interactions in the solid state. Magnetic susceptibility data of planar 4a are fit well by two -J values at 19–22 cm-1. For [Fe4(SR)10]2_, containing adamantane-like Fe4(M2-SR)6 cages with Fe3(ji2-SR)3 rings in the chair conformation, best fits of the magnetic data give one -J value at 32 or 36 cm-1 and one or two others at 42–66 cm-1 depending on the coupling symmetry. MO calculations at the extended Huckel level on suggest that the inherently stable conformation of the ring is planar. This structure is set in large measure by the stereochemical preference of the S-Fe-S angle and by transannular nonbonded repulsions. The decrease in Cl—Cl distances from 6.6 to 3.9 A in changing from the planar to the chair conformation emphasizes the latter effect. In acetonitrile the equilibrium has been approached in both directions and is shifted to the left with decreasing temperature. At K the formation of is essentially complete. In this temperature range the magnetic moment per Fe atom is 4.1-4.2 for 4a in solution and as its crystalline Et4N+ salt. This excellent agreement establishes a planar ring conformation in solution. Thus the results of three crystal structures, MO calculations, and solution and solid state magnetic measurements collectively demonstrate that the near or exact planarity of the Fe3S3 cycles in is an intrinsic property.",
author = "Mark Whitener and Bashkin, {J. K.} and Hagen, {K. S.} and Holm, {R. H.} and Girerd, {J. J.} and E. Gamp and N. Edelstein",
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doi = "10.1021/ja00278a040",
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A New Inorganic Ring System : Planar Fe32-SR)3in [Fe3(SR)3X6]3_—Synthesis, Structures, and Solution Conformation and Equilibrium. / Whitener, Mark; Bashkin, J. K.; Hagen, K. S.; Holm, R. H.; Girerd, J. J.; Gamp, E.; Edelstein, N.

In: Journal of the American Chemical Society, Vol. 108, No. 18, 01.01.1986, p. 5607-5620.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A New Inorganic Ring System

T2 - Planar Fe3(μ2-SR)3in [Fe3(SR)3X6]3_—Synthesis, Structures, and Solution Conformation and Equilibrium

AU - Whitener, Mark

AU - Bashkin, J. K.

AU - Hagen, K. S.

AU - Holm, R. H.

AU - Girerd, J. J.

AU - Gamp, E.

AU - Edelstein, N.

PY - 1986/1/1

Y1 - 1986/1/1

N2 - Anaerobic reaction of equimolar FeX2 and RS” in acetonitrile affords the trinuclear complexes (with X = Cl and R = Ph (4a), p-tolyl (4b), 2,6-Me2C6H3(4d), and X = Br, R = Ph (4c)) isolated as Et4N+ salts. These species constitute the fourth known type of discrete Fe(II) thiolates, the others being [Fe(SR)4]2-, and The following crystallographic results were obtained (crystal system; space group; cell parameters; Z; unique data (I > 3σ(I)); R (%)). (Et4N)3 (4a): monoclinic; C2/c; a = 24.500 (6) A, b = 13.488 (3) A, c = 18.217 (5) A, β = 110.68 (2)°; 4; 2679; 4.9. (Et4N)3a = 15.07 (1) A, b = 22.38 (3) A, c = 20.46 (3) A, β = 91.5 (1)°; 4, 3311; 9.7. (Et4N)3 (4c)-MeCN: hexagonal, P62c; a = b = 13.970 (4) A, c = 18.274 (3) A; 2; 890; 5.7. The reaction system FeBr2+ NaSCH2Ph in acetonitrile yields a different type of compound with the composition (Et4N)2[Fe4(SCH2Ph)6Br4] (5): triclinic; P1; a = 12.874 (2) A, b = 13.949 (3) A, c = 43.272 (8) A, α= 94.85 (2)°, β = 94.07 (2)°, y = 114.98 (1)°; 4; 7402; 6.7. Anions of type 4 contain a new type of inorganic ring system, Fe3(jU2-SR)3, distinguished by its nearly or exactly planar conformation and unusually large Fe-S-Fe angles of ~ 140°, the largest values observed for this angle type. The phenyl groups in 4a and 4c (which has imposed C3h symmetry) are coplanar with the Fe3S3 rings. In 4d these groups are rotated by ~90° owing to the steric effects of the methyl groups. Distorted tetrahedral coordination at each Fe(II) atom is completed by two halide ligands. The planar structure is to be contrasted with the chair-type conformation of the rings in 5 and other species with adamantane-like stereochemistry. Ring conformations influence the extent of antiferromagnetic interactions in the solid state. Magnetic susceptibility data of planar 4a are fit well by two -J values at 19–22 cm-1. For [Fe4(SR)10]2_, containing adamantane-like Fe4(M2-SR)6 cages with Fe3(ji2-SR)3 rings in the chair conformation, best fits of the magnetic data give one -J value at 32 or 36 cm-1 and one or two others at 42–66 cm-1 depending on the coupling symmetry. MO calculations at the extended Huckel level on suggest that the inherently stable conformation of the ring is planar. This structure is set in large measure by the stereochemical preference of the S-Fe-S angle and by transannular nonbonded repulsions. The decrease in Cl—Cl distances from 6.6 to 3.9 A in changing from the planar to the chair conformation emphasizes the latter effect. In acetonitrile the equilibrium has been approached in both directions and is shifted to the left with decreasing temperature. At K the formation of is essentially complete. In this temperature range the magnetic moment per Fe atom is 4.1-4.2 for 4a in solution and as its crystalline Et4N+ salt. This excellent agreement establishes a planar ring conformation in solution. Thus the results of three crystal structures, MO calculations, and solution and solid state magnetic measurements collectively demonstrate that the near or exact planarity of the Fe3S3 cycles in is an intrinsic property.

AB - Anaerobic reaction of equimolar FeX2 and RS” in acetonitrile affords the trinuclear complexes (with X = Cl and R = Ph (4a), p-tolyl (4b), 2,6-Me2C6H3(4d), and X = Br, R = Ph (4c)) isolated as Et4N+ salts. These species constitute the fourth known type of discrete Fe(II) thiolates, the others being [Fe(SR)4]2-, and The following crystallographic results were obtained (crystal system; space group; cell parameters; Z; unique data (I > 3σ(I)); R (%)). (Et4N)3 (4a): monoclinic; C2/c; a = 24.500 (6) A, b = 13.488 (3) A, c = 18.217 (5) A, β = 110.68 (2)°; 4; 2679; 4.9. (Et4N)3a = 15.07 (1) A, b = 22.38 (3) A, c = 20.46 (3) A, β = 91.5 (1)°; 4, 3311; 9.7. (Et4N)3 (4c)-MeCN: hexagonal, P62c; a = b = 13.970 (4) A, c = 18.274 (3) A; 2; 890; 5.7. The reaction system FeBr2+ NaSCH2Ph in acetonitrile yields a different type of compound with the composition (Et4N)2[Fe4(SCH2Ph)6Br4] (5): triclinic; P1; a = 12.874 (2) A, b = 13.949 (3) A, c = 43.272 (8) A, α= 94.85 (2)°, β = 94.07 (2)°, y = 114.98 (1)°; 4; 7402; 6.7. Anions of type 4 contain a new type of inorganic ring system, Fe3(jU2-SR)3, distinguished by its nearly or exactly planar conformation and unusually large Fe-S-Fe angles of ~ 140°, the largest values observed for this angle type. The phenyl groups in 4a and 4c (which has imposed C3h symmetry) are coplanar with the Fe3S3 rings. In 4d these groups are rotated by ~90° owing to the steric effects of the methyl groups. Distorted tetrahedral coordination at each Fe(II) atom is completed by two halide ligands. The planar structure is to be contrasted with the chair-type conformation of the rings in 5 and other species with adamantane-like stereochemistry. Ring conformations influence the extent of antiferromagnetic interactions in the solid state. Magnetic susceptibility data of planar 4a are fit well by two -J values at 19–22 cm-1. For [Fe4(SR)10]2_, containing adamantane-like Fe4(M2-SR)6 cages with Fe3(ji2-SR)3 rings in the chair conformation, best fits of the magnetic data give one -J value at 32 or 36 cm-1 and one or two others at 42–66 cm-1 depending on the coupling symmetry. MO calculations at the extended Huckel level on suggest that the inherently stable conformation of the ring is planar. This structure is set in large measure by the stereochemical preference of the S-Fe-S angle and by transannular nonbonded repulsions. The decrease in Cl—Cl distances from 6.6 to 3.9 A in changing from the planar to the chair conformation emphasizes the latter effect. In acetonitrile the equilibrium has been approached in both directions and is shifted to the left with decreasing temperature. At K the formation of is essentially complete. In this temperature range the magnetic moment per Fe atom is 4.1-4.2 for 4a in solution and as its crystalline Et4N+ salt. This excellent agreement establishes a planar ring conformation in solution. Thus the results of three crystal structures, MO calculations, and solution and solid state magnetic measurements collectively demonstrate that the near or exact planarity of the Fe3S3 cycles in is an intrinsic property.

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