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.