Molecular structure of the novel 3-coordinated Hg(II) complex, aqua-bis(3,3-Dimethylglutarimidato)mercury (II)

The novel complex of biologically active 3,3-dimethylglutarimide, aqua-bis(3,3-dimethylglutarimidato)mercury(II) has been obtained and its structure determined by single crystal X-ray diffraction and vibrational spectroscopic studies. The crystals of C ₁₄H ₂₀N ₂O ₄Hg·H ₂O are monoclinic, space group P2 ₁/c, a=6.085(2), b=19.686(4), c=14.433(3) Å, β=93.32(3)° and Z=4. The structure was solved by heavy atom method and refined to R=0.035, R_w=0.093 for 2075 unique reflections. The mercury atom is almost linearly bonded to two deprotonated nitrogen atoms of the glutarimidate rings [Hg-N=2.035(8) and 2.028(8) Å, N-Hg-N'=169.2(3)°] and is also coordinated to one water molecule in the axial position [Hg-O=2.643(8) Å, N-Hg-O=98.5(3)°]. The water molecule forms strong hydrogen bonds to the carbonyl groups of the neighbouring molecules in the unit cell. The infrared and Raman spectra have provided further evidence for bonding in this complex. It follows that binding of the mercury(II) ion to the deprotonated nitrogen atom of the cyclic 6-membered imides leads to a smaller accommodation of the negative charge on the exocyclic oxygen atoms than analogous binding of Pd(II) with these imides.