In:
Dalton Transactions, Royal Society of Chemistry (RSC), Vol. 50, No. 39 ( 2021), p. 13680-13685
Abstract:
A series of mononuclear Cu II complexes, [Cu II (4-FBA) 2 (py) 2 (H 2 O)] (1), [Cu II (3-FBA) 2 (py) 2 (H 2 O)] (2), and [Cu II (3,4-F 2 BA) 2 (py) 2 (H 2 O)] (3), where 4-FBA = 4-fluorobenzoate, 3-FBA = 3-fluorobenzoate, 3,4-F 2 BA = 3,4-difluorobenzoate, and py = pyridine, respectively, was synthesized and the complexes crystallographically identified. All the Cu II complex crystals share a one-dimensional O–H⋯O hydrogen-bonding chain substructure, although the mutual alignment of fluorinated benzoate (F x BA) ligands exhibits subtle differences among the various compounds, i.e. , F x BA ligands align in an antiparallel fashion in crystals 1 and 3, while 3-FBA ligands in crystal 2 are interdigitated with a tilt along the a axis. Reversible phase transitions were found upon heating at 170.7, 171.3, and 267.5 K for crystals 1, 2, and 3, respectively; all crystals showed approximately 3% expansion and shrinkage of the intermolecular O–H⋯O hydrogen bond distances associated with the thermally activated orientational fluctuations of the F x BA ligands in crystals 1 and 3. The increase in dielectric constant with increasing temperature, at 240 K, activated molecular fluctuation in the 3,4-F 2 BA ligands in crystal 3. Heat capacity measurements indicated that both the expansion and shrinkage of hydrogen bonds, and the molecular fluctuation in 3,4-F 2 BA ligands, contributed to phase transition, and the latter caused dipole fluctuation, resulting in a dielectric anomaly in crystal 3.
Type of Medium:
Online Resource
ISSN:
1477-9226
,
1477-9234
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2021
detail.hit.zdb_id:
1472887-4
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