Bis(triphenyl-λ-phosphanylidene)ammonium hydrogen dichloride

Area of Science:

• Inorganic Chemistry
• Crystallography
• Supramolecular Chemistry

Background:

• The study investigates the structural characteristics of ionic compounds containing complex cations and anions.
• Symmetric hydrogen bonds, particularly in hydrogen dichloride anions, are uncommon and of significant chemical interest.

Purpose of the Study:

• To elucidate the crystal structure of the compound [(Ph(3)P)(2)N][Cl-H-Cl].
• To analyze the symmetry, bonding, and interactions within the cation and anion.
• To characterize the nature of the hydrogen dichloride anion and its hydrogen bonding.

Main Methods:

• Single-crystal X-ray diffraction was employed to determine the three-dimensional structure of the compound.
• Analysis of bond lengths, bond angles, and symmetry elements was performed.
• The hydrogen bonding network and cation-anion interactions were investigated.

Main Results:

• The crystal structure exhibits an overall symmetry of 2, with both the cation and anion lying on a twofold axis.
• The bis(triphenylphosphine)imide cation shows a P-N-P angle of 144.12(13)°, indicating weak cation-anion interactions.
• A rare, almost linear, symmetric hydrogen dichloride anion ([Cl-H-Cl](-)) was observed, characterized by equal Cl-H bond lengths and a short Cl⋯Cl distance.

Conclusions:

• The compound [(Ph(3)P)(2)N][Cl-H-Cl] provides a rare example of a symmetric hydrogen dichloride anion.
• The structural data confirms weak interactions between the bulky cation and the linear anion.
• The findings contribute to the understanding of hydrogen bonding in anionic systems.