The first phosphoramide-mercury(II) complex with a Cl2Hg-OP[N(C)(C)]3 segment

Area of Science:

• Inorganic Chemistry
• Coordination Chemistry
• Relativistic Effects in Chemistry

Background:

• Mercury(II) typically displays linear coordination due to relativistic effects on its 6p orbitals, promoting sp hybridization.
• Mercury(II) acts as a Lewis acid, expanding coordination numbers with weak donor ligands.
• Mercury(II) shows a preference for soft bases (S, N) over hard bases (O).

Purpose of the Study:

• To characterize the crystal structure and coordination environment of a novel mercury(II) complex.
• To investigate the coordination behavior of mercury(II) with a tris(piperidin-1-yl)phosphane oxide ligand.
• To analyze noncovalent interactions within the mercury complex.

Main Methods:

• X-ray crystallography to determine the asymmetric unit and coordination geometry.
• Bond-valence-sum calculations to confirm coordination numbers.
• Analysis of Hg...Cl and Hg...O interactions.

Main Results:

• The asymmetric unit contains a [HgCl2{(C5H10N)3PO}] complex and a discrete HgCl2 unit.
• The mercury(II) center in the complex exhibits a distorted T-shape coordination.
• Bond-valence-sum calculations confirm a three-coordinate mercury(II) atom.

Conclusions:

• The study elucidates the coordination preferences of mercury(II) in a novel complex.
• Relativistic effects and ligand properties dictate mercury(II) coordination geometry.
• Noncovalent interactions play a role in the observed structural features.