Novel Hybrid Spin Systems of 7,7‘,8,8‘-Tetracyanoquinodimethane (TCNQ) Radical Anions and 4-Amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abpt). Crystal Structure of [Fe(abpt)2(TCNQ)2] at 298 and 100 K, Mössbauer Spectroscopy, Magnetic Properties, and Infrared Spectroscopy of the Series [MII(abpt)2(TCNQ)2] (M = Mn, Fe, Co, Ni, Cu, Zn)

P. J. Kunkeler, Petra Van Koningsbruggen, J. P. Cornelissen, A. M. van der Kraan, A. L. Spek, J. G. Haasnoot, J. Reedijk

Research output: Contribution to journalArticle

Abstract

The compound [Fe(abpt)2(TCNQ)2], where TCNQ is the radical anion 7,7‘,8,8‘-tetracyanoquinodimethane and abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, is an Fe(II) complex containing coordinated radical anions which undergoes a thermally induced spin-crossover with Tc = 280 K. Variable-temperature magnetic susceptibility (7−460 K) and 57Fe Mössbauer spectroscopy data give evidence for a complete S = 2 (high-spin) ↔ S = 0 (low-spin) transition, taking place gradually, without hysteresis. The X-ray structure has been determined at 298 K (1) and 100 K (2). The compound crystallizes in the triclinic space group P1̄ with one molecule in the unit cell of dimensions a = 9.277(2) Å, b = 9.876(3) Å, c = 12.272(2) Å, α = 69.52(2)°, β = 86.92(2)°, and γ = 81.73(2)° for 1 and a = 9.236(2) Å, b = 9.684(1) Å, c = 12.137(2) Å, α = 69.26(1)°, β = 87.53(2)°, and γ = 82.38(1)° for 2. Two abpt ligands coordinating via pyridyl-N1A and triazole-N1 are in the equatorial positions. Fe−N1 and Fe−N1A distances are 2.08(1) and 2.12(1) Å for 1 and 2.00(2) and 2.02(1) Å for 2, respectively. TCNQ molecules coordinate axially at remarkably short distances i.e., Fe−N1T = 2.16(1) Å for 1 and 1.93(1) Å for 2. The TCNQ molecules are stacked in pairs yielding diamagnetic entities. The FT-IR spectra (100−300 K) show that the TCNQ νCN vibrations are a fingerprint for the different spin states. In the series of the isostructural [MII(abpt)2(TCNQ)2] (M = Mn, Fe, Co, Ni, Cu, Zn) compounds, the νCN absorptions show a shift to higher frequencies as a function of the crystal field stabilization energy. Above Tc, the Cu(II)-doped Fe(II) species shows a broad signal with g = 2.09 and g = 2.25 and hyperfine structure (A = 180 G). At Tc and below, the spectrum becomes better resolved and now shows superhyperfine structure (AN = 16 G; nine lines). Above Tc, the Mn(II)-doped Fe(II) compound shows a very broad signal at g = 2.00. The spectrum sharpens at Tc to give a clearly resolved spectrum corresponding to a magnetically isolated Mn(II) ion in a tetragonal environment. The signal is split by the zero-field splitting, yielding major signals at g = 1.6 and g = 5.5 and six hyperfine lines (A = 80 G) that are clearly visible on both signals.
Original languageEnglish
Pages (from-to)2190-2197
Number of pages8
JournalJournal of American Chemical Society
Volume118
Issue number9
Early online date6 Mar 1996
DOIs
Publication statusPublished - 6 Mar 1996

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Anions
Infrared spectroscopy
Spectrum Analysis
Magnetic properties
Negative ions
Crystal structure
Spectroscopy
Molecules
Magnetic susceptibility
Hysteresis
Stabilization
Ligands
X rays
Crystals
Ions
Triazoles
Dermatoglyphics
Vibration
1,2,4-triazole
tetracyanoquinodimethane

Keywords

  • Anions
  • iron compounds
  • coordination compounds
  • chemical structure
  • molecular spectroscopy
  • Mossbauer effect

Cite this

@article{0b376ba52b08428b83bb8aff182b9a1f,
title = "Novel Hybrid Spin Systems of 7,7‘,8,8‘-Tetracyanoquinodimethane (TCNQ) Radical Anions and 4-Amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abpt). Crystal Structure of [Fe(abpt)2(TCNQ)2] at 298 and 100 K, M{\"o}ssbauer Spectroscopy, Magnetic Properties, and Infrared Spectroscopy of the Series [MII(abpt)2(TCNQ)2] (M = Mn, Fe, Co, Ni, Cu, Zn)",
abstract = "The compound [Fe(abpt)2(TCNQ)2], where TCNQ is the radical anion 7,7‘,8,8‘-tetracyanoquinodimethane and abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, is an Fe(II) complex containing coordinated radical anions which undergoes a thermally induced spin-crossover with Tc = 280 K. Variable-temperature magnetic susceptibility (7−460 K) and 57Fe M{\"o}ssbauer spectroscopy data give evidence for a complete S = 2 (high-spin) ↔ S = 0 (low-spin) transition, taking place gradually, without hysteresis. The X-ray structure has been determined at 298 K (1) and 100 K (2). The compound crystallizes in the triclinic space group P1̄ with one molecule in the unit cell of dimensions a = 9.277(2) {\AA}, b = 9.876(3) {\AA}, c = 12.272(2) {\AA}, α = 69.52(2)°, β = 86.92(2)°, and γ = 81.73(2)° for 1 and a = 9.236(2) {\AA}, b = 9.684(1) {\AA}, c = 12.137(2) {\AA}, α = 69.26(1)°, β = 87.53(2)°, and γ = 82.38(1)° for 2. Two abpt ligands coordinating via pyridyl-N1A and triazole-N1 are in the equatorial positions. Fe−N1 and Fe−N1A distances are 2.08(1) and 2.12(1) {\AA} for 1 and 2.00(2) and 2.02(1) {\AA} for 2, respectively. TCNQ molecules coordinate axially at remarkably short distances i.e., Fe−N1T = 2.16(1) {\AA} for 1 and 1.93(1) {\AA} for 2. The TCNQ molecules are stacked in pairs yielding diamagnetic entities. The FT-IR spectra (100−300 K) show that the TCNQ νCN vibrations are a fingerprint for the different spin states. In the series of the isostructural [MII(abpt)2(TCNQ)2] (M = Mn, Fe, Co, Ni, Cu, Zn) compounds, the νCN absorptions show a shift to higher frequencies as a function of the crystal field stabilization energy. Above Tc, the Cu(II)-doped Fe(II) species shows a broad signal with g = 2.09 and g = 2.25 and hyperfine structure (A = 180 G). At Tc and below, the spectrum becomes better resolved and now shows superhyperfine structure (AN = 16 G; nine lines). Above Tc, the Mn(II)-doped Fe(II) compound shows a very broad signal at g = 2.00. The spectrum sharpens at Tc to give a clearly resolved spectrum corresponding to a magnetically isolated Mn(II) ion in a tetragonal environment. The signal is split by the zero-field splitting, yielding major signals at g = 1.6 and g = 5.5 and six hyperfine lines (A = 80 G) that are clearly visible on both signals.",
keywords = "Anions, iron compounds, coordination compounds, chemical structure, molecular spectroscopy, Mossbauer effect",
author = "Kunkeler, {P. J.} and {Van Koningsbruggen}, Petra and Cornelissen, {J. P.} and {van der Kraan}, {A. M.} and Spek, {A. L.} and Haasnoot, {J. G.} and J. Reedijk",
year = "1996",
month = "3",
day = "6",
doi = "10.1021/ja943960s",
language = "English",
volume = "118",
pages = "2190--2197",
journal = "Journal of American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "9",

}

TY - JOUR

T1 - Novel Hybrid Spin Systems of 7,7‘,8,8‘-Tetracyanoquinodimethane (TCNQ) Radical Anions and 4-Amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abpt). Crystal Structure of [Fe(abpt)2(TCNQ)2] at 298 and 100 K, Mössbauer Spectroscopy, Magnetic Properties, and Infrared Spectroscopy of the Series [MII(abpt)2(TCNQ)2] (M = Mn, Fe, Co, Ni, Cu, Zn)

AU - Kunkeler, P. J.

AU - Van Koningsbruggen, Petra

AU - Cornelissen, J. P.

AU - van der Kraan, A. M.

AU - Spek, A. L.

AU - Haasnoot, J. G.

AU - Reedijk, J.

PY - 1996/3/6

Y1 - 1996/3/6

N2 - The compound [Fe(abpt)2(TCNQ)2], where TCNQ is the radical anion 7,7‘,8,8‘-tetracyanoquinodimethane and abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, is an Fe(II) complex containing coordinated radical anions which undergoes a thermally induced spin-crossover with Tc = 280 K. Variable-temperature magnetic susceptibility (7−460 K) and 57Fe Mössbauer spectroscopy data give evidence for a complete S = 2 (high-spin) ↔ S = 0 (low-spin) transition, taking place gradually, without hysteresis. The X-ray structure has been determined at 298 K (1) and 100 K (2). The compound crystallizes in the triclinic space group P1̄ with one molecule in the unit cell of dimensions a = 9.277(2) Å, b = 9.876(3) Å, c = 12.272(2) Å, α = 69.52(2)°, β = 86.92(2)°, and γ = 81.73(2)° for 1 and a = 9.236(2) Å, b = 9.684(1) Å, c = 12.137(2) Å, α = 69.26(1)°, β = 87.53(2)°, and γ = 82.38(1)° for 2. Two abpt ligands coordinating via pyridyl-N1A and triazole-N1 are in the equatorial positions. Fe−N1 and Fe−N1A distances are 2.08(1) and 2.12(1) Å for 1 and 2.00(2) and 2.02(1) Å for 2, respectively. TCNQ molecules coordinate axially at remarkably short distances i.e., Fe−N1T = 2.16(1) Å for 1 and 1.93(1) Å for 2. The TCNQ molecules are stacked in pairs yielding diamagnetic entities. The FT-IR spectra (100−300 K) show that the TCNQ νCN vibrations are a fingerprint for the different spin states. In the series of the isostructural [MII(abpt)2(TCNQ)2] (M = Mn, Fe, Co, Ni, Cu, Zn) compounds, the νCN absorptions show a shift to higher frequencies as a function of the crystal field stabilization energy. Above Tc, the Cu(II)-doped Fe(II) species shows a broad signal with g = 2.09 and g = 2.25 and hyperfine structure (A = 180 G). At Tc and below, the spectrum becomes better resolved and now shows superhyperfine structure (AN = 16 G; nine lines). Above Tc, the Mn(II)-doped Fe(II) compound shows a very broad signal at g = 2.00. The spectrum sharpens at Tc to give a clearly resolved spectrum corresponding to a magnetically isolated Mn(II) ion in a tetragonal environment. The signal is split by the zero-field splitting, yielding major signals at g = 1.6 and g = 5.5 and six hyperfine lines (A = 80 G) that are clearly visible on both signals.

AB - The compound [Fe(abpt)2(TCNQ)2], where TCNQ is the radical anion 7,7‘,8,8‘-tetracyanoquinodimethane and abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, is an Fe(II) complex containing coordinated radical anions which undergoes a thermally induced spin-crossover with Tc = 280 K. Variable-temperature magnetic susceptibility (7−460 K) and 57Fe Mössbauer spectroscopy data give evidence for a complete S = 2 (high-spin) ↔ S = 0 (low-spin) transition, taking place gradually, without hysteresis. The X-ray structure has been determined at 298 K (1) and 100 K (2). The compound crystallizes in the triclinic space group P1̄ with one molecule in the unit cell of dimensions a = 9.277(2) Å, b = 9.876(3) Å, c = 12.272(2) Å, α = 69.52(2)°, β = 86.92(2)°, and γ = 81.73(2)° for 1 and a = 9.236(2) Å, b = 9.684(1) Å, c = 12.137(2) Å, α = 69.26(1)°, β = 87.53(2)°, and γ = 82.38(1)° for 2. Two abpt ligands coordinating via pyridyl-N1A and triazole-N1 are in the equatorial positions. Fe−N1 and Fe−N1A distances are 2.08(1) and 2.12(1) Å for 1 and 2.00(2) and 2.02(1) Å for 2, respectively. TCNQ molecules coordinate axially at remarkably short distances i.e., Fe−N1T = 2.16(1) Å for 1 and 1.93(1) Å for 2. The TCNQ molecules are stacked in pairs yielding diamagnetic entities. The FT-IR spectra (100−300 K) show that the TCNQ νCN vibrations are a fingerprint for the different spin states. In the series of the isostructural [MII(abpt)2(TCNQ)2] (M = Mn, Fe, Co, Ni, Cu, Zn) compounds, the νCN absorptions show a shift to higher frequencies as a function of the crystal field stabilization energy. Above Tc, the Cu(II)-doped Fe(II) species shows a broad signal with g = 2.09 and g = 2.25 and hyperfine structure (A = 180 G). At Tc and below, the spectrum becomes better resolved and now shows superhyperfine structure (AN = 16 G; nine lines). Above Tc, the Mn(II)-doped Fe(II) compound shows a very broad signal at g = 2.00. The spectrum sharpens at Tc to give a clearly resolved spectrum corresponding to a magnetically isolated Mn(II) ion in a tetragonal environment. The signal is split by the zero-field splitting, yielding major signals at g = 1.6 and g = 5.5 and six hyperfine lines (A = 80 G) that are clearly visible on both signals.

KW - Anions

KW - iron compounds

KW - coordination compounds

KW - chemical structure

KW - molecular spectroscopy

KW - Mossbauer effect

UR - http://pubs.acs.org/doi/abs/10.1021/ja943960s

U2 - 10.1021/ja943960s

DO - 10.1021/ja943960s

M3 - Article

VL - 118

SP - 2190

EP - 2197

JO - Journal of American Chemical Society

JF - Journal of American Chemical Society

SN - 0002-7863

IS - 9

ER -