Decaborane thiols as building blocks for self-assembled monolayers on metal surfaces

Area of Science:

• Inorganic Chemistry
• Materials Science
• Surface Chemistry

Background:

• Nido-decaborane thiol clusters are novel compounds with potential applications in materials science.
• Understanding their solid-state interactions and surface behavior is crucial for developing new functional materials.

Purpose of the Study:

• To synthesize and characterize three new nido-decaborane thiol cluster compounds.
• To investigate their self-assembled monolayer (SAM) formation on gold and silver surfaces.
• To explore the reactivity of these SAMs as templates for further chemical modifications.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy
• Single-crystal X-ray diffraction analysis
• Quantum-chemical calculations (Density Functional Theory - DFT)
• X-ray photoelectron spectroscopy (XPS)
• Wetting-angle measurements

Main Results:

• Characterization of three nido-decaborane thiol clusters ([1-(HS)-nido-B(10)H(13)], [2-(HS)-nido-B(10)H(13)], and [1,2-(HS)(2)-nido-B(10)H(12)]) using spectroscopy, diffraction, and DFT.
• Observation of weak intermolecular hydrogen bonding in the solid state, with interaction energy proportional to the number of hydrogen atoms involved.
• Successful formation of SAMs on gold and silver, with surface sulfur binding energies correlating to calculated atomic charges.
• Demonstration of SAMs acting as reactive templates, with a platinum complex reacting with the exposed B-H-B bridging hydrogen atoms.

Conclusions:

• Nido-decaborane thiol SAMs exhibit unique surface properties and reactivity.
• The hydrophilic open face directs upward, exposing reactive bridging hydrogen atoms.
• These reactive SAMs serve as unprecedented templates for further surface-based chemistry, with potential for extension to other boron hydride clusters.