Mercury(II) halide complex of <i>cis</i>-[(^<i>t</i>BuNH)(Se)P(μ-N^<i>t</i>Bu)₂P(Se)(NH^<i>t</i>Bu)]

The mercury(II) halide complex [1,3-di-<i>tert</i>-butyl-2,4-bis-(<i>tert</i>-butyl-amino)-1,3,2λ⁵,4λ⁵-di-aza-diphosphetidine-2,4-diselone-κ² <i>Se</i>,<i>Se</i>']di-iodido-mercury(II)<i>N</i>,<i>N</i>-di-methyl-formamide monosolvate, [HgI₂(C₁₆H₃₈N₄P₂Se₂)]·C₃H₇NO or (<b>1</b>)HgI₂, <b>2</b>, containing <i>cis</i>-[( ^<i>t</i> BuNH)(Se)P(μ-N ^<i>t</i> Bu)₂P(Se)(NH ^<i>t</i> Bu)] (<b>1</b>) was synthesized and structurally characterized. The crystal structure of <b>2</b> confirms the chelation of chalcogen donors to HgI₂ with a natural bite angle of 112.95 (2)°. The coordination geometry around mercury is distorted tetra-hedral as indicated by the τ₄ geometry index parameter (τ₄ = 0.90). In the mercury complex, the exocyclic <i>tert</i>-butyl-amido substituents are arranged in an (<i>endo, endo</i>) fashion, whereas in the free ligand (<b>1</b>), the exocyclic substituents are arranged in an (<i>exo, endo</i>) pattern. Compound <b>2</b> displays non-classical N-H⋯O hydrogen-bonding inter-actions with the solvent <i>N</i>,<i>N</i>-di-methyl-formamide. These inter-actions may introduce geometrical distortion and deviation from an ideal geometry. An isostructural HgBr₂ analogue containing <i>cis</i>-[( ^<i>t</i> BuNH)(S)P(μ-N ^<i>t</i> Bu)₂P(S)(NH ^<i>t</i> Bu)] was also synthesized and structurally characterized, CIF data for the compound being presented as supporting information.