Acta Crystallographica Section B

Structural Science

Volume 62, Part 2 (April 2006)

research papers

Acta Cryst. (2006). B62, 245-254 [ doi:10.1107/S0108768105042795 ]

Solvothermal synthesis, multi-temperature crystal structures and physical properties of isostructural coordination polymers, 2C₄H₁₂N⁺[M₃(C₈H₄O₄)₄]^2-·3C₅H₁₁NO, M = Co, Zn

R. Damgaard Poulsen, A. Bentien, M. Christensen and B. Brummerstedt Iversen

Abstract: Two isostructural metal organic framework (MOF) structures have been synthesized by solvothermal methods and examined by single-crystal X-ray diffraction. A microcrystal of 2C₄H₁₂N⁺[Co₃(C₈H₄O₄)₄]^2-·3C₅H₁₁NO (1) was investigated at T = 120 K using synchrotron radiation. 2C₄H₁₂N⁺[Zn₃(C₈H₄O₄)₄]^2-·3C₅H₁₁NO (2) was investigated at multiple temperatures (T = 30, 100, 200 and 300 K) on a conventional diffractometer. The thermal expansion of the structure of (2) is anisotropic and along the a axis, which corresponds to the metal chain direction. The structures contain anionic frameworks with cations and solvent molecules trapped in the voids. The magnetic susceptibility () and heat capacity (C_p) have been measured from 1.8 to 350 K. Compound (1) orders ferromagnetically with a broad phase transition observed in C_p at 6 K. The magnetic moment reaches a value of 3 µ_B per Co at 2 K in a magnetic field of 9 T, and a Curie-Weiss fit to (T) gives an effective moment (_eff) of 4.2 _B and a Weiss temperature ( [theta] ) of 23 K. The exchange mechanism for the magnetic coupling is suggested to involve the Co-O-Co bridges in the individual three-metal-atom subchains. The three-dimensional magnetism presumably is due to super-exchange through two out of the three unique C₈H₄O₄ linker molecules, which have the carboxylate and benzene [pi] systems well aligned.

Keywords: coordination polymers; multi-temperature crystal structures; ferromagnetism; physical properties.


	Structure factor file (CIF format) (467.9 kbytes) [ doi:10.1107/S0108768105042795/lc5040znbdcdef_30Ksup3.fcf ] Contains datablock final

	Structure factor file (CIF format) (413.4 kbytes) [ doi:10.1107/S0108768105042795/lc5040cobdcdef_120Ksup2.fcf ] Contains datablock cobdcdeffinal

	Structure factor file (CIF format) (449.6 kbytes) [ doi:10.1107/S0108768105042795/lc5040znbdcdef_100ksup4.fcf ] Contains datablock znbdcdef_100k_abs

	Structure factor file (CIF format) (431.2 kbytes) [ doi:10.1107/S0108768105042795/lc5040znbdcdef_200Ksup5.fcf ] Contains datablock sad

	Structure factor file (CIF format) (265.4 kbytes) [ doi:10.1107/S0108768105042795/lc5040znbdcdef_300Ksup6.fcf ] Contains datablock abs

Notes:

To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.

The download button will force most browsers to prompt for a file name to store the data on your hard disk.

Where possible, images are represented by thumbnails.