Synchrotron X-ray Charge Density Study of Coordination Polymer Co[subscript 3](C[subscript 8]H[subscript 4]O[subscript 4])[subscript 4[(C[subscirpt 4]H[subscript 12]N)[subscript 2](C[subscript 5]H[subscript 11]NO)[subscript 3] at 16 K
- Aarhus
The charge density (CD) of coordination polymer Co{sub 3}(C{sub 8}H{sub 4}O{sub 4}){sub 4}(C{sub 4}H{sub 12}N){sub 2}(C{sub 5}H{sub 11}NO){sub 3} (1) has been determined from multipole modeling of structure factors obtained from single-crystal synchrotron X-ray diffraction measurements at 16 K. The crystal structure formally contains a negatively charged framework with cations and neutral molecules in the voids. However, the CD suggests that the framework is close to neutral, and therefore qualitative conclusions based on formal charge counting, e.g., about guest inclusion properties, will be incorrect. There are considerable differences in the charge distributions of the three unique benzenedicarboxylic acid linkers, which are widely used in coordination polymers. This suggests that the electrostatic properties of coordination polymer cavities, and thereby their inclusion properties, are highly tunable. The electron density topology shows that the tetrahedrally coordinated Co atom has an atomic volume which is 15% larger than that of the octahedrally coordinated Co atom. The crystal structure has both ferromagnetic and antiferromagnetic interactions, but no direct metal-metal bonding is evidenced in the CD. The magnetic ordering therefore takes place through superexchange in the oxygen bridges and the aromatic linkers. Bonding analysis of the experimental CD reveals that two oxygen atoms, O(1) and O(11), have significant covalent contributions to the metal-ligand bonding, whereas all other oxygen atoms have closed-shell interactions with the metals. This indicates that these two oxygen atoms are the key mediators of the magnetic ordering.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1006679
- Journal Information:
- J. Am. Chem. Soc., Vol. 130, Issue (25) ; 2008; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- ENGLISH
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Related Subjects
43 PARTICLE ACCELERATORS
ANTIFERROMAGNETISM
AROMATICS
ATOMS
BENZENE
BONDING
CATIONS
CHARGE DENSITY
CHARGE DISTRIBUTION
CRYSTAL STRUCTURE
DICARBOXYLIC ACIDS
ELECTRON DENSITY
ELECTROSTATICS
FERROMAGNETISM
INCLUSIONS
INTERACTIONS
METALS
MOLECULES
MULTIPOLES
OXYGEN
POLYMERS
SIMULATION
STRUCTURE FACTORS
SYNCHROTRON RADIATION
TOPOLOGY
VOIDS
VOLUME
X-RAY DIFFRACTION