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

The mercury(II) halide complex [1,3-di-tert-butyl-2,4-bis-(tert-butyl-amino)-1,3,2λ⁵,4λ⁵-di-aza-diphosphetidine-2,4-diselone-κ² Se,Se']di-iodido-mercury(II)N,N-di-methyl-formamide monosolvate, [HgI₂(C₁₆H₃₈N₄P₂Se₂)]·C₃H₇NO or (1)HgI₂, 2, containing cis-[( ^t BuNH)(Se)P(μ-N ^t Bu)₂P(Se)(NH ^t Bu)] (1) was synthesized and structurally characterized. The crystal structure of 2 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 tert-butyl-amido substituents are arranged in an (endo, endo) fashion, whereas in the free ligand (1), the exocyclic substituents are arranged in an (exo, endo) pattern. Compound 2 displays non-classical N-H⋯O hydrogen-bonding inter-actions with the solvent N,N-di-methyl-formamide. These inter-actions may introduce geometrical distortion and deviation from an ideal geometry. An isostructural HgBr₂ analogue containing cis-[( ^t BuNH)(S)P(μ-N ^t Bu)₂P(S)(NH ^t Bu)] was also synthesized and structurally characterized, CIF data for the compound being presented as supporting information.