Molecular structure of a Copper (I) Thiolate and its water-soluble complex

The goal of this research was to develop reproducible methods to crystallize some copper(I) thiolates, denoted [Cuₙ(SR)ₘ]ⁿ⁻ᵐ in which “R” stands for an organic fragment, and obtain high-quality crystal structures of these compounds using single-crystal X-ray diffraction. We specifically focused on obtaining crystal structures of copper(I) 2-hydroxyethanethiolate, CuSCH₂CH₂OH (Cu2ME), and hexakis(2-hydroxyethanethiolato) tetracuprate(I) (Cu₄(SCH₂CH₂OH)₆]²⁻).
This was attempted by crystallizing tetraalkylammonium salts of complexions [Cu₄(SCH₂CH₂OH)₆]²⁻ synthesized according to the equation below:
2NR₄OH + 2HSCH₂CH₂OH + 4CuSCH₂CH₂OH →
2(NR₄)₂[Cu₄(SCH₂CH₂OH)₆] + H₂O

It is hypothesized that using bases with a bulkier alkyl group would allow the entire salt to crystallize due to the similar bulkiness of the Cu₄(SCH₂CH₂OH)₆]²⁻ anion. The crystal structure of neutral Cu₂ME was confirmed from crystals formed by vapor diffusion at room temperature.
Methanolic 3M NH₄OH was the basic solution used to deprotonate 2-mercaptoethanol and dissolve Cu2ME. Diethyl ether was the nonsolvent, and in this case, the complex anion did not crystallize; instead, the Cu2ME starting material formed X-ray quality single crystals, which were analyzed at various temperatures. After attempting various methods, crystals suitable for determining the structure of the [Cu₄(SCH₂CH₂OH)₆]²⁻ complex were formed by vapor diffusion at room temperature using aqueous 1.5 M tetrabutylammonium hydroxide (Bu₄NOH) as the base with tetrahydrofuran (THF) as the nonsolvent. These tetrabutylammonium salts are slated for analysis by single-crystal X-ray diffraction.
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Abstract/Description: The goal of this research was to develop reproducible methods to crystallize some copper(I) thiolates, denoted [Cuₙ(SR)ₘ]ⁿ⁻ᵐ in which “R” stands for an organic fragment, and obtain high-quality crystal structures of these compounds using single-crystal X-ray diffraction. We specifically focused on obtaining crystal structures of copper(I) 2-hydroxyethanethiolate, CuSCH₂CH₂OH (Cu2ME), and hexakis(2-hydroxyethanethiolato) tetracuprate(I) (Cu₄(SCH₂CH₂OH)₆]²⁻). This was attempted by crystallizing tetraalkylammonium salts of complexions [Cu₄(SCH₂CH₂OH)₆]²⁻ synthesized according to the equation below: 2NR₄OH + 2HSCH₂CH₂OH + 4CuSCH₂CH₂OH → 2(NR₄)₂[Cu₄(SCH₂CH₂OH)₆] + H₂O It is hypothesized that using bases with a bulkier alkyl group would allow the entire salt to crystallize due to the similar bulkiness of the Cu₄(SCH₂CH₂OH)₆]²⁻ anion. The crystal structure of neutral Cu₂ME was confirmed from crystals formed by vapor diffusion at room temperature. Methanolic 3M NH₄OH was the basic solution used to deprotonate 2-mercaptoethanol and dissolve Cu2ME. Diethyl ether was the nonsolvent, and in this case, the complex anion did not crystallize; instead, the Cu2ME starting material formed X-ray quality single crystals, which were analyzed at various temperatures. After attempting various methods, crystals suitable for determining the structure of the [Cu₄(SCH₂CH₂OH)₆]²⁻ complex were formed by vapor diffusion at room temperature using aqueous 1.5 M tetrabutylammonium hydroxide (Bu₄NOH) as the base with tetrahydrofuran (THF) as the nonsolvent. These tetrabutylammonium salts are slated for analysis by single-crystal X-ray diffraction.
Subject(s): Undergraduate Research
Date Issued: 2021