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Thiacrown Pt(II) complexes with group 15 donor ligands: pentacoordination in Pt(II) complexes
Gregory J Grant1, Desirée A Benefield, Donald G VanDerveer
1Department of Chemistry, The University of Tennessee at Chattanooga, Chattanooga, TN 37403, USA. Greg-Grant@utc.edu
Dalton Transactions (Cambridge, England : 2003)
|October 8, 2009
Summary
This study synthesizes new platinum(II) and palladium(II) thiacrown complexes with group 15 donors. Complex structures and electronic properties are detailed, revealing trends related to donor ligand identity and size.
Area of Science:
- Coordination Chemistry
- Organometallic Chemistry
- Materials Science
Background:
- Thiacrown ligands, such as 1,4,7-trithiacyclononane ([9]aneS3), are versatile chelating agents in coordination chemistry.
- Platinum(II) and Palladium(II) complexes with sulfur-containing ligands exhibit diverse structural and electronic properties.
- Group 15 donor ligands (e.g., phosphines, arsines, stibines) play a crucial role in tuning the reactivity and stability of metal complexes.
Purpose of the Study:
- To synthesize and characterize novel thiacrown complexes of Pt(II) and Pd(II) featuring various group 15 donor ligands.
- To investigate the structural and electronic consequences of incorporating different group 15 donors into Pt(II)-[9]aneS3 frameworks.
- To explore the relationship between ligand properties and the resulting complex's coordination geometry and spectroscopic behavior.
Main Methods:
- Synthesis of Pt(II) and Pd(II) complexes using [Pt([9]aneS3)Cl2] as a precursor.
- Characterization techniques including multinuclear NMR (1H, 13C, 195Pt), IR, and UV-Vis spectroscopies.
- Single crystal X-ray diffraction for detailed structural determination.
Main Results:
- Successful synthesis of six new Pt(II) and one Pd(II) thiacrown complexes.
- X-ray structures reveal axial M-S interactions, with bond distances sensitive to the group 15 donor (Sb < As < P).
- Unusual five-coordinate distorted trigonal bipyramidal geometries observed in bis-pnictogen complexes due to intramolecular pi-pi interactions.
- 195Pt NMR chemical shifts and NMR line broadening correlate with donor atom size and ligand field strength.
Conclusions:
- The electronic and steric properties of group 15 donor ligands significantly influence the structure and fluxional behavior of Pt(II) thiacrown complexes.
- The observed trends in axial M-S distances and coordination geometries provide insights into metal-ligand bonding in these systems.
- This work expands the library of thiacrown complexes and offers a foundation for designing related materials with tailored properties.
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