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Synchrotron X-ray charge-density study of coordination polymer [Mn(HCOO)2(H2O)2]infinity
Rasmus D Poulsen1, Mads R V Jørgensen, Jacob Overgaard
1Department of Chemistry, University of Aarhus, 8000 Arhus C, Denmark.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|November 10, 2007
Summary
This study reveals the charge density of a manganese coordination polymer using X-ray diffraction. The findings provide a benchmark for understanding magnetic properties in similar materials.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- Coordination polymers are structurally simple yet exhibit complex magnetic behavior.
- Understanding the charge density is crucial for elucidating bonding and magnetic interactions.
Purpose of the Study:
- To determine the accurate charge density of [Mn(HCOO)2(H2O)2]infinity (1) using multiple X-ray diffraction datasets.
- To compare charge densities obtained under varying experimental conditions.
- To investigate the nature of metal-ligand bonding and magnetic properties.
Main Methods:
- Single-crystal X-ray diffraction at 100 K and 16 K using conventional and synchrotron sources.
- Multipole modeling of experimental structure factors for charge density determination.
- Magnetic susceptibility and heat capacity measurements.
- Comparison with ab initio theory.
Main Results:
- Good agreement between charge densities derived from different datasets.
- The 16 K synchrotron dataset provided the most accurate charge density.
- Topological analysis and atomic charges indicate ionic, high-spin Mn atoms.
- Magnetic ordering arises from superexchange interactions.
Conclusions:
- The study provides a benchmark charge density for metal formate dihydrates.
- Charge density analysis supports a predominantly ionic model for the Mn atoms.
- Discrepancies with previous spin density measurements highlight the importance of accurate charge density data.
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