Relation Between Structure and Magnetic Exchange Interactions in the Mixed Metal Complexes

Abstract

The copper and nickel complexes of (prp)2en (2-hydroxypropiophenone imine) have been used as ligands to form binuclear complexes with the bis(hexafluoroacetylacetonato)metal(II) complexes M′(hfa)2, where M′ = copper(II), nickel(II), cobalt(II), and manganese(II). The structures of the resulting binuclear complexes M((prp)2en)M′(hfa)2 were determined from single-crystal X-ray diffraction using counter methods, and their magnetic properties were studied using high-precision magnetic susceptibility measurements in the range 4-300 K. The complexes consist of a four-coordinated metal atom M in a distorted planar environment and M′ in a distorted octahedron: The extent of distortion of the planar geometry about M is approximately constant for all of the complexes, but the geometry about M′ is distorted to different degrees in the different complexes, and the distortion is greatest when M′ = Cu and least when M′ = Mn. The complexes with Cu((prp)2en) exhibited antiferromagnetic exchange interactions, while the complexes with Ni((prp)2en) are essentially magnetically normal, exhibiting the expected properties of the M′ ion. The structural similarity of the complexes with Cu((prp)2en) and Ni((prp)2en) therefore requires that the interactions observed in Cu((prp)2en)M′(hfa)2 are entirely intramolecular in origin. The magnetic interactions in the hfa complexes from Cu((prp)2en) are relatively weak when compared with those of analogous dimeric halide complexes; for Cu((prp)2en)Cu(hfa)2, the singlet-triplet separation, -2J, is 44.8 cm-1, compared with 232 cm-1 for a typical related complex for which the main molecular change in substitution is Cl for hfa. The J values in the Cu((prp)2en)M′(hfa)2 complexes correlate with the structural features regardless of the nature of M′ for the series studied. Crystal data for Cu((prp)2en)Cu(hfa)2: space group P21/c, Z = 4, a = 13.702 (3) Å, b = 20.010 (8) Å, c = 12.579 (3) Å, β = 96.81 (1)°, V = 3424 Å3, R = 4.0%, 3508 reflections. Crystal data for Ni((prp)2en)Cu(hfa)2: space group P1, Z = 2, a = 10.484 (3) Å, b = 12.446 (8) Å, c = 13.766 (3) Å, α = 91.00 (4)°, β = 92.60 (2)°, γ = 110.73 (4)°, V = 1677 Å3, R = 3.5%, 3440 reflections. Crystal data for Cu((prp)2en)Co(hfa)2: space group P21/c, Z = 4, α = 13.576 (7) Å, b = 20.281 (7) Å, c = 12.540 (7) Å, β = 97.99 (5)°, V = 3419 Å3, R = 4.2%, 3254 reflections. Crystal data for Ni((prp)2en)Co(hfa)2: space group P21/c, Z = 4, a = 13.468 (3) Å, b = 20.307 (5) Å, c = 12.587 (2) Å, β = 97.42 (2)°, V = 3413 Å3, R = 5.6%, 4075 reflections. Crystal data for Cu((prp)2en)Mn(hfa)2: space group P21/c, Z = 4, a = 13.511 (6) Å, b = 20.65 (1) Å, c = 12.548 (5) Å, β = 97.60 (4)°, V = 3470 Å3, R = 4.4%, 2550 reflections. Crystal data for Ni((prp)2en)Mn(hfa)2: space group P21/c, Z = 4, a = 13.387 (7) Å, b = 20.61 (1) Å, c = 12.605 (5) Å, β = 97.07 (4)°, V = 3452 Å3, R = 4.6%, 2409 reflections. © 1979 American Chemical Society.

Department(s)

Chemistry

International Standard Serial Number (ISSN)

0020-1669

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1979 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Jan 1979

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