Smallest Optical Gap for Pt(II)-Pt(IV) Mixed-Valence Pt-Cl and Pt-Br Chain Complexes Achieved by Using a...

Area of Science:

• Materials Science
• Inorganic Chemistry
• Solid-State Physics

Background:

• Halogen-bridged metal complexes, particularly platinum chain complexes, are investigated for their unique electronic and optical properties.
• Controlling interatomic distances and electronic structures is crucial for tuning the performance of these materials.
• Previous studies have explored various methods to modify the properties of these complexes.

Purpose of the Study:

• To investigate the effect of multiple-hydrogen-bond interactions on Pt-X-Pt distances in Cl- and Br-bridged Pt chain complexes.
• To synthesize and characterize novel platinum chain complexes incorporating hydrogen-bonding functionalities.
• To evaluate the impact of these modifications on the electronic and optical properties, including optical gap and electrical conductivity.

Main Methods:

• Synthesis of novel platinum chain complexes: [Pt(dabdOH)2Cl]Cl2 (5) and [Pt(dabdOH)2Br]Br2 (6), where dabdOH is (2 S,3 S)-2,3-diaminobutane-1,4-diol.
• Utilizing a multiple-hydrogen-bond approach by incorporating hydroxy groups in the ligands to interact with counteranions.
• Characterization of structural parameters, including Pt-X-Pt distances, using X-ray diffraction.
• Measurement of optical properties, specifically the optical gap, using spectroscopic techniques.
• Assessment of electrical conductivity at room temperature.

Main Results:

• Complex 5 exhibited the shortest Pt-Cl-Pt distance (5.0747(8) Å) reported for Cl-bridged Pt chain complexes.
• The synthesized complexes achieved the smallest optical gaps for Cl- or Br-bridged Pt chain complexes (1.45 eV for 5 and 1.19 eV for 6).
• Complex 6 demonstrated the highest electrical conductivity (1.9 × 10^-5 S cm^-1) among all reported Br-bridged Pt chain complexes.

Conclusions:

• The introduction of additional hydrogen bonds between ligands and halides is an effective strategy to enhance the electronic properties of halogen-bridged metal complexes.
• This approach allows for precise control over structural parameters like Pt-X-Pt distances, leading to improved material performance.
• The study highlights the potential of hydrogen-bonding interactions in designing advanced functional materials based on metal-halide chains.