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Structure, Formation, and Dynamics of Mo 12 and Mo 16 Oxothiomolybdenum Rings Containing Terephtalate Derivatives
Author(s) -
Lemonnier JeanFrançois,
Floquet Sébastien,
Marrot Jérôme,
Terazzi Emmanuel,
Piguet Claude,
Lesot Philippe,
Pinto André,
Cadot Emmanuel
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601369
Subject(s) - molybdenum , chemistry , aqueous solution , ring (chemistry) , nuclear chemistry , crystallography , inorganic chemistry , organic chemistry
The influence of rigid or semirigid dicarboxylate anions, terephtalate (TerP 2− ), isophtalate (IsoP 2− ), and phenylenediacetate (PDA 2− ) on the self‐condensation process of the [Mo 2 O 2 S 2 ] 2+ dioxothio cation has been investigated. Three new molybdenum rings, [Mo 12 O 12 S 12 (OH) 12 (TerP)] 2− ([Mo 12 TerP] 2− ), [Mo 16 O 16 S 16 (OH) 16 (H 2 O) 4 (PDA) 2 ] 4− ([Mo 16 (PDA) 2 ] 4− ), and [Mo 16 O 16 S 16 (OH) 16 (H 2 O) 2 (IsoP) 2 ] 4− ([Mo 16 (IsoP) 2 ] 4− ) have been isolated and unambiguously characterized in the solid state by single‐crystal X‐ray studies and in solution by various NMR methods and especially by diffusion‐correlated NMR ( 1 H DOSY) spectroscopy, which was shown to be a powerful tool for the characterization and speciation of templated molybdenum ring systems in solution. Characterization by FT‐IR and elemental analysis are also reported. The dynamic and thermodynamic properties of both the sixteen‐membered rings were studied in aqueous medium. Specific and distinct behaviors were revealed for each system. The IsoP 2− /[Mo 2 O 2 S 2 ] 2+ system gave rise to equilibrium, involving mono‐templated [Mo 12 IsoP] 2− and bis‐templated [Mo 16 (IsoP) 2 ] 4− ions. Thermodynamic parameters have been determined and showed that the driving‐force for the formation of the [Mo 16 (IsoP) 2 ] 4− is entropically governed. However, whatever the conditions (temperature, proportion of reactants), the PDA 2− /[Mo 2 O 2 S 2 ] 2+ system led only to a single compound, the [Mo 16 (PDA) 2 ] 4− ion. The latter exhibits dynamic behavior, consistent with the gliding of both the stacked aromatic groups. Stability and dynamics of both Mo 16 rings was related to weak hydrophobic or π–π stacking inter‐template interactions and inner hydrogen‐bond network occurring within the [Mo 16 (IsoP) 2 ] 4− and [Mo 16 (PDA) 2 ] 4− ions.