A Unique Dinuclear CuII Compound with Two Phase Transitions Clearly Visible from Thermal and Magnetic Behaviour; Synthesis, Magnetism and X-ray Structures at Three Temperatures of Bis(di-2-pyridylamine)bis(μ-hydroxo)bis(μ-perchlorato-O,O)dicopper(II)
✍ Scribed by Sujittra Youngme; Gerard A. van Albada; Huub Kooijman; Olivier Roubeau; Wasit Somjitsripunya; Anthony L. Spek; Chaveng Pakawatchai; Jan Reedijk
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 182 KB
- Volume
- 2002
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
A new compound, [Cu(dpyam)(OH)] 2 (ClO 4 ) 2 (dpyam = di-2pyridylamine) is studied in detail and characterised by magnetic susceptibility and heat capacity measurements. This unique compound exhibits two phase transitions at 192 and 116 K. To obtain more insight into the origin of this transition, X-ray crystal structures at 3 different temperatures, below (1A, 110 K), between (1B, 150 K) and above (1C, 200 K) the transitions are measured. The structure consists of a dinuclear Cu II unit with two bridging hydroxo groups and with two ligands bound to each copper atom via N, while the axial sites are occupied by oxygen atoms of bridging perchlorate anions, providing a distorted tetragonal environment with a Cu-Cu distance which varies from 2.9328(6) to 2.9633(6) A ˚, and a Cu-O-Cu angle which varies from 99.00(9) to 100.53(9)°. In all three structures, the Cu 2 O 2 L 2 unit does not change significantly. The only changes involve the position of the perchlorate anions and their H bonds with the bridging