Mononuclear and binuclear chromium(III) picolinate complexes

Diane M Stearns, William H. Armstrong

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Abstract

The chromium(III) picolinate complexes [Cr(pic)3] (1) and [Cr(pic)2OH]2 (2) (where pic = 2-carboxypyridine) have been isolated from the reaction of chromium(III) chloride and picolinic acid in aqueous solution. The monomeric complex 1·H2O (CrC18H14N3O7) crystallizes in the monoclinic space group C2/c with a = 30.219 (3) Å, b = 8.529 (1) Å, c = 13.942 (2) Å, β = 95.141 (1)°, V = 3579 (2) Å3, Z = 4, R = 0.032, and Rw = 0.043 for 1815 reflections (I > 3σ(I)). The binuclear complex 2·5H2O (Cr2C24H28N4O15) crystallizes in the monoclinic space group P21/n with a = 12.569 (2) Å, b = 18.839 (3) Å, c = 13.000 (4) Å, β = 105.823 (3)°, V = 2962 (2) Å3, Z = 8, R = 0.046, Rw = 0.067 for 3250 reflections (I > 3σ(I)). The mononuclear complex 1 is the meridional isomer, not the facial isomer as previously assumed. For 2 the bridging geometry is as follows: Cr-Cr = 2.999 (1) Å; Cr-O(bridge) range = 1.934 (3)-1.980 (3) Å; Cr-O-Cr = 99.0 (1), 101.6(1)°; O-Cr-O = 79.4 (1), 79.9 (1)°. Magnetic susceptibility data for 2 were measured from 280 to 6 K and can be fit using an isotropic spin-exchange Hamiltonian, H = -2JŜ1·Ŝ2 with a weak antiferromagnetic interaction (J=-8.02(4)cm-1), g = 1.844, and a 2.23 (4) mol% paramagnetic impurity. The extent of magnetic coupling in 2 is compared to predictions made by the Glerup-Hodgson-Pedersen (GHP) equation. Compounds 1 and 2 are discussed in the general context of biologically active chromium.

Original languageEnglish (US)
Pages (from-to)5178-5184
Number of pages7
JournalInorganic Chemistry
Volume31
Issue number25
StatePublished - 1992
Externally publishedYes

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Chromium
chromium
isomers
Isomers
spin exchange
Hamiltonians
Magnetic couplings
Magnetic susceptibility
chlorides
aqueous solutions
magnetic permeability
Chlorides
impurities
acids
Impurities
geometry
predictions
Geometry
picolinic acid

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Mononuclear and binuclear chromium(III) picolinate complexes. / Stearns, Diane M; Armstrong, William H.

In: Inorganic Chemistry, Vol. 31, No. 25, 1992, p. 5178-5184.

Research output: Contribution to journalArticle

Stearns, DM & Armstrong, WH 1992, 'Mononuclear and binuclear chromium(III) picolinate complexes', Inorganic Chemistry, vol. 31, no. 25, pp. 5178-5184.
Stearns, Diane M ; Armstrong, William H. / Mononuclear and binuclear chromium(III) picolinate complexes. In: Inorganic Chemistry. 1992 ; Vol. 31, No. 25. pp. 5178-5184.
@article{308ddd5e818c4947918ac6f62b752027,
title = "Mononuclear and binuclear chromium(III) picolinate complexes",
abstract = "The chromium(III) picolinate complexes [Cr(pic)3] (1) and [Cr(pic)2OH]2 (2) (where pic = 2-carboxypyridine) have been isolated from the reaction of chromium(III) chloride and picolinic acid in aqueous solution. The monomeric complex 1·H2O (CrC18H14N3O7) crystallizes in the monoclinic space group C2/c with a = 30.219 (3) {\AA}, b = 8.529 (1) {\AA}, c = 13.942 (2) {\AA}, β = 95.141 (1)°, V = 3579 (2) {\AA}3, Z = 4, R = 0.032, and Rw = 0.043 for 1815 reflections (I > 3σ(I)). The binuclear complex 2·5H2O (Cr2C24H28N4O15) crystallizes in the monoclinic space group P21/n with a = 12.569 (2) {\AA}, b = 18.839 (3) {\AA}, c = 13.000 (4) {\AA}, β = 105.823 (3)°, V = 2962 (2) {\AA}3, Z = 8, R = 0.046, Rw = 0.067 for 3250 reflections (I > 3σ(I)). The mononuclear complex 1 is the meridional isomer, not the facial isomer as previously assumed. For 2 the bridging geometry is as follows: Cr-Cr = 2.999 (1) {\AA}; Cr-O(bridge) range = 1.934 (3)-1.980 (3) {\AA}; Cr-O-Cr = 99.0 (1), 101.6(1)°; O-Cr-O = 79.4 (1), 79.9 (1)°. Magnetic susceptibility data for 2 were measured from 280 to 6 K and can be fit using an isotropic spin-exchange Hamiltonian, H = -2JŜ1·Ŝ2 with a weak antiferromagnetic interaction (J=-8.02(4)cm-1), g = 1.844, and a 2.23 (4) mol{\%} paramagnetic impurity. The extent of magnetic coupling in 2 is compared to predictions made by the Glerup-Hodgson-Pedersen (GHP) equation. Compounds 1 and 2 are discussed in the general context of biologically active chromium.",
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T1 - Mononuclear and binuclear chromium(III) picolinate complexes

AU - Stearns, Diane M

AU - Armstrong, William H.

PY - 1992

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N2 - The chromium(III) picolinate complexes [Cr(pic)3] (1) and [Cr(pic)2OH]2 (2) (where pic = 2-carboxypyridine) have been isolated from the reaction of chromium(III) chloride and picolinic acid in aqueous solution. The monomeric complex 1·H2O (CrC18H14N3O7) crystallizes in the monoclinic space group C2/c with a = 30.219 (3) Å, b = 8.529 (1) Å, c = 13.942 (2) Å, β = 95.141 (1)°, V = 3579 (2) Å3, Z = 4, R = 0.032, and Rw = 0.043 for 1815 reflections (I > 3σ(I)). The binuclear complex 2·5H2O (Cr2C24H28N4O15) crystallizes in the monoclinic space group P21/n with a = 12.569 (2) Å, b = 18.839 (3) Å, c = 13.000 (4) Å, β = 105.823 (3)°, V = 2962 (2) Å3, Z = 8, R = 0.046, Rw = 0.067 for 3250 reflections (I > 3σ(I)). The mononuclear complex 1 is the meridional isomer, not the facial isomer as previously assumed. For 2 the bridging geometry is as follows: Cr-Cr = 2.999 (1) Å; Cr-O(bridge) range = 1.934 (3)-1.980 (3) Å; Cr-O-Cr = 99.0 (1), 101.6(1)°; O-Cr-O = 79.4 (1), 79.9 (1)°. Magnetic susceptibility data for 2 were measured from 280 to 6 K and can be fit using an isotropic spin-exchange Hamiltonian, H = -2JŜ1·Ŝ2 with a weak antiferromagnetic interaction (J=-8.02(4)cm-1), g = 1.844, and a 2.23 (4) mol% paramagnetic impurity. The extent of magnetic coupling in 2 is compared to predictions made by the Glerup-Hodgson-Pedersen (GHP) equation. Compounds 1 and 2 are discussed in the general context of biologically active chromium.

AB - The chromium(III) picolinate complexes [Cr(pic)3] (1) and [Cr(pic)2OH]2 (2) (where pic = 2-carboxypyridine) have been isolated from the reaction of chromium(III) chloride and picolinic acid in aqueous solution. The monomeric complex 1·H2O (CrC18H14N3O7) crystallizes in the monoclinic space group C2/c with a = 30.219 (3) Å, b = 8.529 (1) Å, c = 13.942 (2) Å, β = 95.141 (1)°, V = 3579 (2) Å3, Z = 4, R = 0.032, and Rw = 0.043 for 1815 reflections (I > 3σ(I)). The binuclear complex 2·5H2O (Cr2C24H28N4O15) crystallizes in the monoclinic space group P21/n with a = 12.569 (2) Å, b = 18.839 (3) Å, c = 13.000 (4) Å, β = 105.823 (3)°, V = 2962 (2) Å3, Z = 8, R = 0.046, Rw = 0.067 for 3250 reflections (I > 3σ(I)). The mononuclear complex 1 is the meridional isomer, not the facial isomer as previously assumed. For 2 the bridging geometry is as follows: Cr-Cr = 2.999 (1) Å; Cr-O(bridge) range = 1.934 (3)-1.980 (3) Å; Cr-O-Cr = 99.0 (1), 101.6(1)°; O-Cr-O = 79.4 (1), 79.9 (1)°. Magnetic susceptibility data for 2 were measured from 280 to 6 K and can be fit using an isotropic spin-exchange Hamiltonian, H = -2JŜ1·Ŝ2 with a weak antiferromagnetic interaction (J=-8.02(4)cm-1), g = 1.844, and a 2.23 (4) mol% paramagnetic impurity. The extent of magnetic coupling in 2 is compared to predictions made by the Glerup-Hodgson-Pedersen (GHP) equation. Compounds 1 and 2 are discussed in the general context of biologically active chromium.

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